Sea Level Inc

04/01/2025

Serpae Tetra Care Guide 🐟 (Red Minor Tetra) 🐟 Beginner Care For Serpae Tetras

About The Serape Tetra, also known as the Red Minor Tetra or Blood Tetra is a colorful fish native to the slow-moving waters of the Amazon River in South America and has an average lifespan of about 7 years. These brightly colored fish are great for beginner and experienced aquarists alike. They are typically inexpensive, can be kept in a smaller aquarium, and are a very hardy fish. One thing to make note of is that these fish tend to have a twitchy spastic style of swimming. Unlike many other species of fish, they tend to move in short bursts as opposed to smoothly swimming for long distances. This type of behavior is normal, but can sometimes be alarming to beginner aquarium hobbyists, who are not familiar with these types of fish.

Tank Set Up:

When it comes to tank set up, keep in mind that tetras do best in well-established aquariums, so you want to make sure the tank is fully cycled, and the water parameters are stable before adding them to the aquarium. Serpae tetras need a minimum tank size of 10 gallons, although personally I would recommend at least a 20-gallon tank. They do best in soft, neutral to slightly acidic water with a pH of between 6-7.5 and temperatures between 72°-79°F, so you may or may not need a heater for them. Serpae Tetras do best in a more dimly lit environment and thrive in Blackwater aquariums. A well planted aquarium with driftwood, floating plants, and a darker sandier substrate is best if trying to mimic their natural environment.

Tank Mates:

Serpae Tetras are a schooling fish, so you will need to keep a minimum of 5 in the tank, although they tend to act less aggressive when kept in larger numbers of 15 or more. These tetras are known to be extreme fin nippers, so you will want to keep this in mind if you decide to keep them in a community tank. This type of behavior is typically seen most while the tetras are establishing a pecking order, so it is best not to keep them with other fish that may have long delicate fins. Some examples these fish typically do well with are other species of tetras, corydoras, plecos, platies, or swordtails.

Diet:

When it comes to diet, serape tetras are far from picky eaters. These fish do well with a diet consisting of a high-quality pellet food, along with frozen or live foods such as bloodworms, tubifex worms, and brine shrimp.

Breeding Serpae Tetras:

They are an egg laying species that are relatively easy to breed. As these fish are known to eat their eggs, you would want to set up a separate tank for breeding. For your breeding tank you will want to set up a small very dimly lit aquarium, with dark substrate, low flow filtration, and provide either a spawning mop, or plants such as java moss. The water in this tank should be kept at warmer temperatures of between 78°-80°F When choosing your mating fish, it is easiest to tell the difference between male and female when they are ready to spawn. Males are much more brightly colored than their female counterparts, females are also typically larger with a rounder body, whiles males are more slender, and the dorsal fin on males will be black, while females’ dorsal fin will be paler in color. To condition your spawning pair, you will want to feed them a variety of foods, preferably live or frozen. As these fish are known to eat their eggs, once they have laid them, you will want to remove them from the tank. Keep in mind these eggs will be very sensitive to light, so if you have a light on your breeding tank, you will want to keep it off. Eggs should hatch within 1-2 days and fry can be fed fry food, or baby brine shrimp once they are free swimming.

I’m sure John at Sea Level, Now in Minnetonka, has a tank full of Serpae Tetras or Red Minor Tetras, maybe go in and pick up a school. They are a pretty shade of red!

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03/01/2025

10 Best Algae Eating Fish For Freshwater Fish Tanks!

Keeping your freshwater aquarium clean and free of algae can be a challenge, but adding algae-eating fish can make this task much easier. These fish not only help control algae growth but also add beauty and diversity to your tank. Here’s a list of the 10 best algae-eating fish for freshwater tanks, each known for their efficiency and compatibility with various tank setups.

1. Siamese Algae Eater (Crossocheilus oblongus)

Overview: Siamese Algae Eaters are one of the best algae eaters available. They are known for their effectiveness in eating various types of algae, including black beard algae.

Benefits:

• Great at controlling different algae types
• Active and peaceful
• Easy to care for

2. Bristlenose Pleco (Ancistrus spp.)

Overview: Bristlenose Plecos are small, hardy, and efficient algae eaters. They are perfect for smaller tanks and are less likely to outgrow your aquarium compared to common plecos.

Benefits:

• Excellent at cleaning glass and decorations
• Hardy and easy to care for
• Unique appearance with bristles

3. Otocinclus Catfish (Otocinclus spp.)

Overview: Otocinclus Catfish, or Otos, is small, peaceful fish that are highly effective at cleaning algae off plant leaves, glass, and other surfaces.

Benefits:

• Gentle and non-aggressive
• Perfect for planted tanks
• Effective at cleaning small areas

4. Amano Shrimp (Caridina multidentata)

Overview: Although not a fish, Amano Shrimp are excellent algae eaters and are highly effective in planted tanks. They are known for their ability to eat a wide range of algae.

Benefits:

• Eat a variety of algae types
• Peaceful and good for community tanks
• Help with detritus clean-up

5. Siamese Flying Fox (Epalzeorhynchos kalopterus)

Overview: The Siamese Flying Fox is often confused with the Siamese Algae Eater but is equally effective at controlling algae, particularly black beard algae.

Benefits:

• Active and interesting to watch
• Good at controlling stubborn algae
• Suitable for larger community tanks

6. Twig Catfish (Farlowella spp.)

Overview: Twig Catfish are excellent at camouflaging and are known for their ability to eat algae, particularly off plant surfaces and decorations.

Benefits:

• Unique appearance
• Effective at cleaning plant leaves
• Peaceful and suitable for community tanks

7. Chinese Algae Eater (Gyrinocheilus aymonieri)

Overview: Chinese Algae Eaters are efficient at cleaning algae but can become territorial as they mature. They are best suited for larger tanks.

Benefits:

• Great at cleaning tough algae
• Hardy and adaptable
• Active and interesting to watch

8. Molly Fish (Poecilia spp.)

Overview: Mollies are versatile fish that eat algae and add color to your tank. They are livebearers and can help control algae growth naturally.

Benefits:

• Easy to breed
• Colorful and active
• Good for community tanks

9. Nerite Snail (Neritina spp.)

Overview: While not a fish, Nerite Snails are among the best algae eaters. They are highly effective at cleaning algae off glass, rocks, and decorations.

Benefits:

• Cannot reproduce in freshwater, preventing overpopulation
• Eat a variety of algae types
• Easy to care for

10. Siamese Loach (Botia histrionica)

Overview: The Siamese Loach is a great addition to larger tanks. They are efficient algae eaters and are also known to eat leftover food and detritus.

Benefits:

• Active and social
• Help with overall tank cleanliness
• Suitable for larger community tanks

Conclusion:

Incorporating algae-eating fish and invertebrates into your aquarium is an effective way to maintain water quality and clarity. These species not only help control algae but also add diversity and interest to your tank. For top-quality algae-eating fish and other aquarium products, visit Sea Level, now in Minnetonka. Trust Sea Level to provide expert quality advice and the best products to keep your aquarium thriving!

I'm sure that John at Sea Level has most of these algae-eating fish in stock. Maybe if you need some algae eaters, maybe stock up on fish food!

02/01/2025

What Is The Cause Of Hair Algae!

Hair algae are quite commonly found green algae. They form coats, from which densely packed short filaments grow. They form carpet-like layers, growing over plants and decoration. These algae usually belong to the genus Oedogonium. The species in this genus differ by the length and build of their filaments. Hair algae with longer, soft filaments are frequently found in aquaria.

Common Causes:

Like many green algae, hair algae appear mainly during the cycling phase of a tank, when the biological system is still finding its balance. After some more time, when the nutrients are optimally balanced and when a sufficient number of algae-eating aquarium animals are present, hair algae will disappear all by themselves. Algae with softer filaments are eaten by invertebrates like Amano shrimp and most dwarf shrimp species. Even snails like the highly popular Ramshorn snails will go after the filamentous hair algae coats. There is one species with short, hard, bristle-like filaments, which is not commonly found but very stubborn.

Like green thread algae, hair algae can appear due to a nutrient imbalance, for example when some nutrients or CO2 are deficient. However, overly long lighting hours or too intense a light above the tank can be a reason for their occurrence. It is important to give the algae lots of competition on the form of a large number of fast-growing aquarium plants. For them to grow healthily and happily, a balanced supply of nutrients is vital, especially when it comes to macronutrients. In the following you'll find a list of these nutritive elements and the recommended content in the water. Using a CO2 injection system in combination with liquid fertilizers facilitates supplying your aquatic plants with everything they need.

 A CO2 content of approximately 20-30 mg/l, just use the simple to use Fluval CO2 Aquarium Indicator Kit.
 10 to 25 mg/l of nitrate (NO3), Tetra EasyStrips Complete Kit 25, 6 in 1 Testing Strips and 25 Ammonia Testing Strips.
 5 to 10 mg/l of potassium (K), I’m Sure That API has a Test Kit For Potassium.
 0.1 to 1 mg/l of phosphate (PO4), API Phosphate Test Kit for Freshwater and Saltwater.
 Less Than 10 mg to l of magnesium (Mg), Some of the Tetra EasyStrips Complete Kit 25, 6 in 1 Testing Strips Must Also Test For Magnesium.

In the following, we'd like to explain the most common causes for green algae in more detail:
Is CO2!

John down at Sea Level has all these test kits on his shelves, ready and waiting for you buy me and put me to good use for your wet pets!
The content of dissolved CO2 in the aquarium water is best monitored with a Fluval CO2 Aquarium Indicator Kit
The ideal concentration of CO2 is at around 20 to 30 mg/l.

Light:

If the light is too strong in relation to the requirements of the plants and the nutrient supply, hair algae may occur. When you switch to another light system or leave on your light for a longer time, always adapt your plant mass and your fertilization regime. It is very important that the light requirements of the aquatic plants are in accordance with the lighting system. Most nurseries have a traffic light system to categorize their plants (green - undemanding, yellow - moderate, red - demanding). This is also a hint towards how much light a plant needs.
Moreover, we recommend keeping the daily lighting period in a newly set-up tank rather short, like only 6 hours, in the early stages. Increase by 30 minutes every week. If your light has a moderate to strong output, leave it on for a maximum of 10 hours per day. Tanks with weak light can be lit for up to 12 hours. You don't know just how strong your aquarium light is?

Nitrate:

Often stunted growth in aquatic plants is due to a lack of nitrogen. This can be diagnosed by testing the water with the appropriate water test for nitrate. Just use the simple API Nitrate 90-Test Freshwater and Saltwater test kit. When the plants stop growing, especially green algae soon take advantage of this situation and use the nutrient imbalance to take over the tank. With good liquid fertilizers like for example API LEAF ZONE Freshwater Aquarium Plant Fertilizer 18-Ounce Bottle White, you can boost the nitrate (NO3) content in a targeted way. Other macronutrients like potassium or phosphate are not added by these fertilizers. If there is a lack of nitrate in your tank you can raise the content to the optimal level by a one-time stock fertilization with Seachem Flourish Potassium 500mL. Combined with this measure you ought to adjust your regular fertilization regime, be it weekly or daily, with a nitrate-only fertilizer.
Nutrient imbalances are often caused by a slack-off in maintenance. Please note: a regular water change is vital! Exchange at least 50% of the aquarium water for fresh water once a week. Besides the addition of fresh, unpolluted water a regular water change prevents certain nutrients from building up in your tank.

Control:

As we've already said above: The typical countermeasures that are used against green algae in general also help against hair algae: the use of a sufficient number of algae eaters (for example Amano shrimp, and other algae eaters) hand in hand with an optimization of the fertilizer regimen, especially in the area of macronutrients. Is your tank still cycling? Then stay calm, it is absolutely normal that algae appear during this phase. When your aquarium has been running for a longer time, the ecosystem will become more and more stable, and the water plants will be able to out compete the algae. If only a few leaves are infested, just cut them off and throw them away.
If the hair algae only grow in a few spots in your tank, try just removing the leaves, or just remove the whole plant and throw it away. Or if it’s your favorite plant, then you could try and cutting the plant off at the gravel and leave the root ball in the gravel and it might grow back or it die, but it’s worth a chance.

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12/02/2024

Cardinal Tetra Complete Care Guide:

Cardinal Tetra is the perfect beginner fish:

They are hardy, easy to care for and very colorful.
A group of them is great for showing off their vibrant colors, and their synchronized movements are almost hypnotic.
Cardinal Tetras are being bred more and more, they are now a common sight in community fish tanks.
If you want to keep these fish, you will need to know their ideal environment, diet and tank mates. We will cover all of this and much more in this article…

Category Rating

Care Level: Easy
Temperament: Peaceful
Color Form: Blue and Red
Lifespan: Up to 5 years
Size: Up to 2″
Diet: Omnivore
Family: Characidae
Minimum Tank Size: 20 Gallons
Tank Set-Up: Tropical freshwater with open swimming
Compatible: Peaceful community

The Cardinal Tetra (Paracheirodon Axelrodi) is a social fish from the Characidae family. They are sometimes referred to as Red Neon Tetra due to their similarity to the famous Neon Tetra.
Cardinal Tetras are growing in popularity and can be found in most pet stores for as little as $2.
These fish are native to the Orinoco and Negro Rivers in South America. This continent is home to many species of Tetra, though some are found in Africa and Central America.
They are easy to incorporate into a community aquarium.
Even beginners can enjoy the color and activity they bring with them because they are hardy and enjoy a range of conditions.

In a clean tank, they can live for up to five years:

Typical Behavior:

Cardinal Tetras are a colorful shoaling species that love to be kept in groups – the larger the group the better (just make sure the tank is big enough). They will swim together in the middle and upper levels of the tank.
They are much more confident when around others of their own kind. If kept alone they would become stressed and shy, and also lose some color. They are easily bullied by aggressive fish as they are unable to defend themselves.
Like most Tetras, they are peaceful and make a great addition to a community aquarium, but they can be kept in a species only tank too.

Appearance of Cardinal Tetra:

This small fish only reaches 2 inches long:

The main attraction of Cardinal Tetras is their color. Their fins are small and don’t grab your attention.
Their bodies are typically red and blue. A red stripe runs along the lower side from head to tail, a blue stripe sits just on top. The colors are bright, so a shoal can be a striking sight.
Evidence suggests that these species can change their colors too.
Whilst red and blue is the most popular color, you can find them in gold’s and silvers (these are much less common).
It is very difficult to identify the males from the females because they have the same coloration. You can spot females if they are carrying eggs because they will have a rounded body.
You do not usually need to s*x this species since they are kept in large groups, so you will likely have a good mix of males and females.

Cardinal Tetra vs. Neon Tetra:

These fish are often confused with Neon Tetras as they have the same coloration.
The main difference is a Neon Tetra’s red stripe only runs halfway up their body, and their blue stripe is a less vibrant blue.

Cardinal Tetra Habitat and Tank Requirements:

Cardinal Tetras naturally live in flooded forest areas, shallow creeks and tributaries to large rivers in South America.
Although there are plants and rocks spread around the bottom of the water column, there is lots of open space for swimming.
The environment would be warm and slightly acidic and the shallow waters move slowly. Some areas receive lots of sunlight, and others are heavily shaded.
Understanding a fish’s natural habitat is great for helping you setup the perfect tank for them.

Tank Conditions:

These fish don’t venture to the bottom of the aquarium very often, so you can choose any substrate. If you are starting a community with bottom-dwellers, a sandy substrate is best because they are less likely to scratch themselves.
You can scatter around some decorations, but plants are ideal if you are trying to provide some shelter. Your Cardinal Tetras will hide in them when stressed.
Anubias Nana, Amazon Swords and Java Fern are some easy species to care for.
Make sure that you leave plenty of open water for swimming, as this is where your fish will spend most of their time together.
You need to maintain suitable water conditions – keep the temperature between 73-81°F and the pH should be 6-7. The filter outlet will create enough water movement and most standard aquarium lights are fine.

What Size Aquarium Do Cardinal Tetras Need?

Whilst Cardinal Tetras are small, they tend to live in large groups so you need a tank that can accommodate a group of at least six.
A 20 gallon aquarium will provide enough swimming space to meet their active lifestyle.
Two gallons per additional Tetra is fine.

Cardinal Tetra Tank Mates:

This peaceful species is suitable for community aquariums.
They stick to their own shoals and will generally ignore anything else in the tank. Therefore, they can be kept with most other peaceful fish.
Aggressive or territorial species will bully your Cardinal Tetra, stressing them out to the point of death – one example of this is the Rainbow Shark.
Large fish should be avoided too as Cardinal Tetra are small and easily eaten by those with large mouths.
Some good tank mates include: Neon Tetras, Zebra Danios, Hatchetfish, Mollies, Dwarf Gourami, Angelfish and Guppies.
Zebra Loaches, Yoyo Loaches and Otocinclus work well if you are looking for occupants in the lower regions of your tank.
Cherry Shrimp and Mystery Snails are also compatible and are a great way to diversify the behaviors in your tank.

Keeping Cardinal Tetras Together:

You should definitely be keeping Cardinal Tetra in groups. They need to be in shoals of at least six to bring out their natural behaviors.
The bigger the shoal, the happier they will be.

Cardinal Tetra Diet and Feeding:

Cardinal Tetra is omnivorous, and will eat virtually anything you put into your tank.
There are many types of fish food available, and each has their pros and cons.
Generally it is best to mix a few types into a fish’s diet to make sure they are receiving a balanced diet.
Dried foods are the easiest to get your hands on. They are the most commonly sold and usually the cheapest. However, for that convenience you sacrifice most of the nutritional content. There are far fewer nutrients in dried foods compared to live or frozen foods.
Live and frozen foods are full of nutrients, so you should use them to supplement the rest of their diet. You can also add green vegetables to the tank. This varies the diet and helps to prevent food waste. Chop them up and only give them small amounts.
Feed adults twice a day, giving them what they can easily finish in two minutes. If any food is left over, remove it before it breaks down in the water.

Care:

The Cardinal Tetra is an easy fish to care for:

They are fairly undemanding and can tolerate a range of water conditions and setups. However, they can get ill just like all aquarium fish.
One of the most important parts of caring for them is choosing the right diet. If your Cardinal Tetras are not receiving the nutrients they need, then they will lose their color and their immune systems will weaken.
Another thing that can weaken the immune system is a sudden change in environmental conditions. For example, these fish cannot survive a drop of temperature for long.
Not only do parameters need to remain stable, but the aquarium should be kept clean. Regular water changes prevent the buildup of pollutants. You should also wipe down excess algae before it can cause issues.
One disease to look out for in your tank is Neon Tetra Disease, which affects many species of Tetra. It is caused by a parasite and leads to symptoms such as a loss of color, cysts, a curved spinal and secondary infections.
It usually enters the tank when adding UN-quarantined fish or feeding with infected live foods. There is no known cure for this disease, most infected fish are euthanized. Remove them from the tank as quickly as possible so that they are not eaten and don’t infect other fish.
Other diseases that you might experience are fin rot, ich and bloat. These are more well-known and much easier to treat.

Breeding Cardinal Tetra:

Cardinal Tetras will naturally breed upstream in shaded regions.
The good news is they can be bred at home; they just need quality conditions which replicate their natural breeding environment.
Start by switching off aquarium lights.
You need to stay on top of cleaning your tank, weekly water changes are important for this. Parameters must remain stable and you cannot let pollutants or algae build up.
A nutritional diet is also important for getting your fish ready to mate. A female will have a more rounded body when she’s ready because she will be carrying eggs. She will let a male swim alongside her as they move around plants. They will then release the s***m and eggs.
Eggs should hatch after three days.
The fry will be too small to eat an adult diet, so feed them tiny foods like infusoria until they are big enough. The young will be photosensitive once hatched, so gradually raise the light intensity back to normal conditions.
After 8-12 weeks, they should have the colors to match the adults.

Is the Cardinal Tetra Right For Your Aquarium?

Beginners will feel very comfortable with Cardinal Tetra.
They are hardy and peaceful, so they can be kept in a range of tropical setups. They are an undemanding fish which makes it simple to design a suitable tank. Feeding them is just as simple, and you could even try to breed them.
A shoaling species like this is a very attractive option for your aquarium. You will love to watch them move around the tank in unison, showing off their bright colors as they swim.

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11/01/2024

How to Raise & Lower KH (Carbonate Hardness) in Aquarium Water & What is KH

What is aquarium KH?
Carbonate hardness is referred to as KH for short Potassium Hardness, as Potassium in the periodic table K stands for Potassium. It’s basically a measure of carbonates (CO3) and bicarbonates (HCO3) dissolved in your water.
Don’t worry! You don’t need to remember those words. You just need to know what KH is and why it’s important. And, that is actually simple…
Think of KH as a protective barrier that surrounds your pH. As your aquarium creates acids, they eat away at KH instead of affecting your pH
However, this barrier is not permanent and once gone, your pH is free to move around again.
The higher the KH of your aquarium, the more acid it can neutralize before the pH is affected.
KH is invisible. While it exists in your water, you won’t be able to know how much is there without a special test kit.
You might also hear KH referred to as the alkalinity of the water.
Important: Don’t confuse alkalinity with alkaline.
• Alkaline: The opposite end of the pH scale to acidic (also referred to as basic).
• Alkalinity: The measure of acid neutralization (KH).
And just to confuse you more, you may also hear KH referred to as the following…
• Carbonate hardness
• Temporary hardness
• Total alkalinity
• Buffering capacity/buffer
• Acid-neutralizing capacity (ANC)
These can all be used interchangeably. So, if they ever come up in conversation, remember that they all refer to the same thing:
KH!
Sea Level Fact: Carbonate Hardness is shortened to KH because it is derived from the German spelling of the word, Karbonate Hardness.
What Is The Difference Between KH And GH?
Beginners often confuse carbonate hardness (KH) with general hardness (GH). While both have the word hardness in their name, they measure different parameters of your water.
Carbonate hardness (KH): The measure of carbonates and bicarbonates dissolved in water.
General hardness (GH): The measure of magnesium and calcium dissolved in water.
If you have ever heard someone say…
I have really hard water where I live.
They are talking about GH.
In nature, GH and KH go hand in hand. If a waterway has a high GH, it will also have a high KH.
But tap water is usually anything but natural…
It’s actually possible for your tap water to have a really high GH and a very low KH. So, just having a high GH does not automatically mean that you also have a high KH.
Why Is KH Important To Your Aquarium?
As I touched on earlier, KH prevents acids from causing your pH to swing.
Rapid changes in pH can shock and even kill your fish. So yeah, it’s something you want to avoid!
Now, here is what you might not be aware of:
Your aquarium constantly produces acids!
You know those beneficial bacteria that live in your filter, the ones you introduced when you cycled your tank? Well, they are to blame.


You see, fish p**p breaks down into ammonia. Beneficial bacteria that live in your filter turn the ammonia into nitrite and then finally into nitrate.
But here’s the thing…
Nitrite and nitrate are acidic!
And because they are constantly being produced, the pH of your aquarium will decrease over time.
If you’re KH (carbonate hardness) is low or non-existent, then nothing can neutralize these acids.
This leads to an unsafe drop in pH that can make the water toxic for fish and plants.
KH is the invisible superhero in your tank that stops this from happening. As you see, it’s important to maintain some level of KH in your tank, no matter what species you keep.
In saltwater tanks, KH serves a second purpose. Corals use carbonates to build their exoskeletons. If you are creating a reef tank, you’ll need to watch that KH!
Sea Level Tip: Have you ever tried to lower the pH of your tank but noticed it didn’t change? KH (carbonate hardness) is preventing the change. You need to reduce your KH before you can adjust the pH.
What is the best KH level for your tank?
The ideal KH levels entirely depend on what you stock in your tank.
Let’s look at the suggested ranges for different types of aquariums. While the measurements can be listed as part per million (PPM), I prefer to use degrees of carbonate hardness (dKH).1 dKH is about equivalent to 17.9 ppm
Please note, the following recommendations are rough guidelines only. Your specific fish, plants or invertebrates may require more precise KH levels outside these ranges.
Freshwater KH:
Tropical Fish Tank 4-8 dKH
Shrimp Tank 2-5 dKH
African Cichlid Tank 10-18 dKH
Discus 3-8 dKH
Planted Tank 3-8 dKH
Brackish Tank 10-18 dKH
Pond 4-8 dKH

Saltwater KH:
Saltwater Tank 8-12 dKH
Reef Tank 8-12 dKH
Will Increasing My KH Also Raise My pH?
Yes!
The two go hand in hand.
Generally, as KH rises so does pH. But don’t let this scare you away from maintaining a healthy KH.
Having a stable pH that is a little high is much better than a pH that swings up and down all the time.
How do you test the KH of your aquarium?
It’s important to know the KH level of your water.
Unfortunately, because KH is invisible, you’ll need a special aquarium test kit to do it…
Don’t worry! It’s affordable and easy-to-use. Best of all, a single KH test kit can last for hundreds of tests – just follow the instructions.
Sea Level Note: The results of the test can be given in dKH or PPM. Which you use is a matter of choice. I personally use dKH and refer to it from now on.
While there are aquarium test strips available that can also test for carbonate hardness or KH, I don’t recommend them. Based on personal experience, test strips are much less accurate than liquid test kits.
You may be wondering…
How often should you test the KH of your aquarium water?
Well, it all depends on your results of your first test strip!
For Freshwater Tanks:
• 4 dKH or lower: Check your KH weekly.

• 5 dKH or higher: Check your KH monthly.

• You should test not only your tank but also your tap water. This will give you a greater understanding of how to go about adjusting your KH if you need to.

• For saltwater tanks:

• I recommend testing your KH weekly. You should also check the KH of your salt mix, just to make sure everything is as it should be.

• How Do You Increase KH?

• Tested your aquarium water and want to raise your KH?
• Let’s take a closer look at how you can do exactly that.

• 1. Water Changes:

Many water supplies across America have a KH high enough that performing a water change will replenish the KH levels in your freshwater tank.
Test your tap water and see if it is over 4 dKH. If so, a weekly 25% water change will replace the depleted KH.
Take this time to also maintain your tank. I highly recommend buying a good gravel cleaner and using it to suck the entire gunk out of your substrate. Doing so will help prevent nitrates from building up and decreasing your KH.
As for saltwater tanks, a good salt mix should contain all the essential ingredients needed to restore the KH in your tank.
2. Alkalinity Buffers:
Freshwater Tank Alkalinity Buffer:
Many aquarium brands manufacture their own line of alkaline buffer products. Depending on the brand, they may rely on baking soda, soda ash or phosphate to increase KH.
So, why wouldn’t you use each of these individual products instead?
Well, the manufacturers of alkalinity buffers have spent a great deal of time ensuring consistency. These ingredients are mixed with other elements to ensure that you achieve your expected KH.
Marine Tank Alkalinity Buffer:
For beginners, I personally recommend using an alkalinity buffer over other methods in this list because it takes the guesswork out of adjusting your KH.
Best of all, there is an alkalinity buffer designed to match exactly what you stock in your aquarium…
Reef Tank Alkalinity Buffer:
There is even alkalinity buffers designed for specific species of fish, including…
• Goldfish buffer
• Discus buffer
• Malawi Victoria buffer
• Tanganyika buffer
• Arowana buffer
There Really Is An Alkalinity Buffer For Everyone!
Sea Level Tip: Avoid phosphate-based buffers. Phosphates can deplete essential minerals like calcium and magnesium from your aquarium. Also, high phosphate levels can help fuel algae outbreaks and stunt coral growth.
3. Crushed Coral
Yep, this is exactly what it sounds like. Crushed coral comes from dead coral reefs. Because it is high in calcium carbonate, crushed coral can help boost your tank’s KH.
Crushed coral can either be mixed in with your substrate or placed in a media bag and added to your filter.
Best of all, you don’t need to add it to your tank constantly. You just let it sit there and do its thing.
How does it work?
Remember those acids I mentioned earlier in the guide?
Well, these acids react with the crushed coral, causing it to release calcium and carbonate into your water, raising both the KH and GH.
How much crushed coral should you use?
It doesn’t really matter. You see, adding more crushed coral will just cause it to increase the KH and GH faster.
However, given enough time, a small or large amount of crushed coral will eventually raise the KH and GH to the same point. Your water will equalize.
This is because as your pH rises, it becomes less acidic, and the coral won’t release as much calcium and carbonate.
I personally recommend adding crushed coral to your filter. If you add crushed coral to your gravel, it can compact over time, trapping fish waste, uneaten food and other gunk. If you do add it to your gravel, only use a small amount rather than laying down a thick layer.
4. Aragonite:
Aragonite is the crystal form of calcium carbonate (CaCO3). Just like with crushed coral, acids in the water cause aragonite to release calcium and carbonate.
However, unlike crushed coral, aragonite is made up of tiny sand-like grains. Because of this, it is often used as substrate sand in both freshwater and saltwater aquariums.
Aragonite can greatly increase pH, GH and KH over time. So, it’s best suited to hard-water-loving fish like African cichlids.
I don’t recommend aragonite for beginners. If you decide it’s messing up your water parameters, you’ll have to remove the entire substrate – a frustrating job once your tank is set up.
5. Dolomite rock:
Dolomite rock, sometimes called dolostone, is a calcareous rock made up mostly of calcium, magnesium and carbonate CaMg(CO3)2.
As you might expect, it will release all three of these elements into your aquarium, raising both the KH and GH of your tank.
Dolomite will release less of these ingredients at a higher pH. Because of this, dolomite is more commonly used in freshwater aquariums. The higher pH of saltwater tanks reduces the dolomite’s effectiveness.
Dolomite is available in a wide variety of colors, making it suitable to be used as a substrate.
6. Soda Ash:
Soda ash is sodium carbonate (Na2CO3). Because it can greatly increase pH, it is mostly used in saltwater tanks.
If you want to add soda ash to your tank, it’s best to add small daily doses rather than a larger weekly dose. This will give you a better opportunity to react to how it is affecting your pH.
How much soda ash should you use? Bulk Reef Supply has a great calculator that takes the guesswork out of dosing.
How do you decrease KH?
As I mentioned earlier, KH helps prevent your pH from dropping.
But what if the pH of your tank or tap water is too high for your fish or planted tank?
Well, to lower your pH, you first have to lower your KH.
And if your water has a naturally high KH, then you have to lower that before you have any success at reducing the pH.
While raising your KH is a simple task, lowering it is more difficult. A balance needs to be struck between KH and pH. Otherwise, you’ll experience pH swings that can kill your fish.
Decreasing KH is really only done in freshwater aquariums. Let’s take a closer look at the different ways to reduce the KH levels of your tank…
1. Acid Buffers:
To put it simply, acid buffers convert KH to carbon dioxide (CO2). The result is a reduced KH and a lower pH.
My number one tip when using an acid buffer:
Go slow!
Acid buffers are primarily used in planted tanks where the plants remove the extra carbon dioxide from the water.
However, if you don’t have plants, overdosing can result in both excess CO2 and a plummeting pH.
And, the end result is a bunch of dead fish.
So again, follow the instructions and take your time. You can always add more later.
2. Distilled Water:
Distilled water is water that has undergone a special process to make it pure…
The water is heated until it turns to steam; it is then passed through a cooler and collected in a separate container. All the impurities are left behind. The result is nearly pure water – no KH.
You can find it on the shelf of your local grocery store in gallon jugs.
Now, you want to mix this water with your tap water as you still want some KH and GH.
But by mixing it with say 50% tap water, it will adjust the KH accordingly. Use your aquarium test kit to determine the correct ratio.
The downside is the cost. Even though distilled water is fairly cheap per gallon, the costs can soon add up. Weekly water changes on a large tank can require a surprising amount of water.
For this reason, distilled water is best used for smaller tanks.
If you have a larger-sized aquarium, then my next solution is more appropriate.
3. RO/DI Water:
Make your own pure water with one of the following units:
• Reverse Osmosis (RO) System
• Deionization (DI) Filter
Both of these devices can be used to create “pure water” with no KH.
While the set-up costs may be pricey, it will save you a considerable amount of money in the long term, especially if you buy bottles of distilled water each week.
Just like distilled water, you want to mix RO/DI water with your tap water to ensure there is at least some KH and GH. The RO/DI water will reduce your KH proportionately to how much you mix in.
If you have a saltwater tank, it’s basically expected that you will have one of these units nearby.
4. Indian Almond Leaf:
Indian almond leaf is a favorite for lowering the KH and pH of freshwater tanks. It’s particularly popular in betta tanks.
As the Indian almond leaves break down in your tank, they release tannic acid (tannins). These tannins eat away at the KH.
Indian almond leaves may also have medicinal properties; naturally protecting betta fish from skin issues and helping wounds heal.
The downside to Indian almond leaves is that they gently lower the KH and pH of your aquarium water. If your water has a significantly high KH, you might not notice much of a difference.
5. Peat Moss:
Peat is dried and chopped peat moss. Put it in a mesh bag and place it inside your filter.
Like Indian almond leaves, peat leaches tannic acid (tannins) into the water to reduce the KH and pH a bit. Again, it’s best used where only a small reduction in KH is needed.
If you want to use peat to lower your KH, buy an aquarium-safe variety. Many types of peat are sold for use in gardening and are mixed with chemicals to cut down on mold, which could kill your fish.
Why Should Your KH Levels NEVER Reach Zero?
For freshwater aquariums, you might have come across advice to lower your KH (carbonate hardness) to zero.
A KH of zero is particularly dangerous because it can lead to unsafe drops in pH that makes the tank toxic to both fish and plants.
Ideally, you want to maintain at least some level of KH in your tank, no matter what type of species you keep.
I most commonly come across this advice for fish like discus or certain types of shrimp. And yes, it’s true there are plenty of fish that live in a natural environment where the water has a KH very close to zero.
But here’s the thing. Those waterways have a LOT of other variables that help keep the pH level relatively stable.
No matter how hard you try, you cannot consistently replicate that environment in something as small as your aquarium.
Unless you are an expert fish keeper, I highly recommend that your aquarium has some degree of KH.
Fish need a stable pH for long and healthy lives. KH helps you achieve just that.
Conclusion:
For beginners, KH or carbonate hardness is one of the most overlooked and least understood elements of aquarium chemistry. And, I can’t help but feel that API not including a KH test in their master test kit is part of the reason.
But never fear because now you know everything there is to know about it.
As you see, KH plays a vital role in keeping your water parameters stable.
Without it, your pH would bounce all over the place, stressing your fish and causing all kinds of problems.
And if you want to adjust your pH, then you need to change your KH first.
I’m sure John at Sea Level will get you test set kit, that you might need; all you need to do is ask him!