My 29 Gallon Kuhli Loach Tank

This post covers a lot of useful information. Please read carefully and take notes. There will be a quiz.

It probably is a good idea to talk about an actual aquarium, so here is my 29 gallon bowfront.

In this tank I have:

  1. 19 Striped Kuhli Loaches,
  2. 8 Marimo Moss Balls,
  3. 3 Amazon Swords,
  4. A Java Fern,
  5. An Anubias Nana,
  6. Water Wisteria,
  7. And that floating thing on the top right that I think is a Cabomba,
  8. I also have pond snails, lots of pond snails…

Look at my cute little linguini.

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As far as actual hardware:

  1. Aquatop CF300 (264 GPH)
  2. COODIA Aquarium Hood Lighting (LED)
  3. Hydor Koralia Powerhead
  4. Cascade Head Aquarium Heater with Thermostat
  5. Dr. Moss Glass Co2 Diffuser
  6. ISTA CO2 Bubble Counter
  7. 5# Aluminum CO2 Cylinder
  8. ISTA CO2 Regulator (This one is a little more expensive than most regulators, but for a good reason!)

Now that what I use is nicely listed let me explain a little about what each thing does and how it’s set up.

1. Aquatop Filter:

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The filter I have is a three stage filter. The first stage is a standard filter sponge with a bag of Seachem Matrix Carbon. The second stage is a slightly finer filter sponge with Seachem Purigen. The last stage is bioballs.

In general, activated carbon is there to remove stuff. It helps with removing supplements such as medications and plant fertilizer and can also minimize fish tank odor and water discoloring agents (tannins, more on what these are later.). The Seachem Matrix Carbon is standard activated carbon shaped like small spheres. This shape allows for maximum water flow-through and minimal packing.


The Purigen helps with controlling ammonia, nitrites, and nitrates through absorption. It also makes the water very clear. Purigen is rechargeable too (not infinitely), but the back of the container comes with specific instructions which must be followed exactly of you will harm your fish. Note that you may need to get a special bag since the Purigen polymers are very small.

Many senior aquarists look down on bioballs. The biggest complaint about them is the increased production of nitrates. I’ll happily take a nitrate factory over increased ammonia or nitrites. This result means you have cycled your aquarium properly, and you’re getting a slow increase of nitrates as you should.

As the name implies, bioballs are part of the biological filtration system, while the other two stages are mechanical filtration. Any good filtration system has a mix of mechanical and biological. In larger tanks, I’ve seen people have two canisters, one for biological and one for mechanical filtration. This method isn’t necessary, as long as you have good mechanical filtration before your bioballs, you’ll have a strong filter.

2. COODIA Aquarium Hood Lighting (LED)

I picked this light because it was the lowest cost LED light and it fit my aquarium. But I ended up liking it. It emits full spectrum white light during the day and a soft blue at night with adjustable intensities (unfortunately it isn’t automatic). It works for medium light plants.

3. Hydor Koralia Powerhead

IMG_3986 - CopyA Powerhead isn’t something you need unless you have a planted freshwater aquarium. I kind of wish I had looked into it a little sooner.

I was starting to notice some indications of CO2 deficiency in my plants and my CO2 indicator was either reading “too low” or “too high.” So I did some thinking and came to the realization that I probably should have some water flow.

Ever since then, my CO2 has been perfect. If you have a planted tank, get one of these.

4. Cascade Aquarium Heater

Tropical fish need warm water (even betta fish). It is a good idea to invest in a fully submersible heater with a built in thermostat. There are cheaper ones that aren’t adjustable, but they make your options limited in the future (if you have an ich outbreak, for example). A thermometer is also helpful, but not essential. The thermometer of choice can be as simple or as complicated as you want.

I have two. On the heater side I have a stick-on liquid crystal thermometer, and on the opposite side, I have a digital. I did this while treating ich; it allows me to make sure the temperature is consistent throughout the tank.

5,  6, 7, & 8. CO2 Stuff


Injecting CO2 is a big step for most people. Most people don’t have plants at all, but if you want to get some plants, this setup is an advisable one. The initial cost is high, but the cost of refilling a 5# CO2 tank is less than $20.

You may be looking into those CO2 systems that use disposable CO2 cartridges. Don’t. I did that at first, and it gets to be incredibly expensive and, if you have more than a couple of plants, will run out in less than a week.

My tank has a 5# CO2 tank. The regulator I use has a built in relay, which allows you to connect the power cable to a timed outlet allowing for full automation (you don’t want CO2 on at night). The best part of this is turning it on every morning doesn’t involve adjusting the regulator to make sure the bubble count is correct.

The CO2 hose goes through a bubble counter, then to the glass diffuser.

NOTE: CO2 lowers pH. I use pH neutralizer, and my aquarium reads 6.2-6.5 consistently.

Please refer here for more info on freshwater plants.

Now that I’ve covered the tank hardware in a very brief 700 words let’s move on to stock!

Tank Stocking: Kuhli Loaches

Kuhli Loaches are awesome. They feel safest when they have hiding places, or they get very stressed. They like to be in groups of 6 or more (though they do not school or shoal). If you have fewer, you’ll never see them, but if there are more, you’ll see them everywhere. They tend to open up and be very active fish in groups. Many sources say they are nocturnal fish, but mine all appear to be the opposite.

Kuhli loaches like 75-86°F (24-30°C), a pH of 5.5-6.5, and a hardness of about 5.0 dGH. They will eat almost anything that gets to the bottom (including the shrimp that I use to have that died. Shrimp and plant fertilizers don’t mix well). I feed them a single Tetra Pro Cory Wafer daily.

Marimo Moss Balls

Marimos are dark green balls of algae (don’t worry, these are good). The only care they require is when you do a water change you rinse them off and squeeze them a few times in the old water to get the dirt out. They are extremely hardy and impossible to kill, unless you really try. Fish love them. I always see several Kuhli Loaches hiding in the group I have. I got mine at Marimo Pet Store. Don’t pay the $5-$6 per moss ball that you see in the pet stores.

Amazon Swords

Amazon Swords require medium light. They are taller and are perfect for plants in the back that can cover up your filter intake and thermometer. They like a temperature between 72°-82°F (22°-28°C), and a pH from 6.5 to 7.5. For those using fluorescent lights, they need 5000 – 7000K.

Java Fern

Like the Swords, Java Fern also requires medium light. They do best when tied to something like driftwood using fishing line. Over time they’ll attach themselves to the wood and begin to spread. Those above lead them to be a mid-level plant. I made a mistake with mine, and it’s not doing too well now (I planted it, didn’t do enough research). They like a temperature of 62°-82°F (16°-28°C) and a pH of 6.0 – 7.5. The also need 5000 – 7000K.

Anubias Nana

These are also a medium light plant (seeing a theme here?). They should also be attached to something like driftwood, and will slowly propagate. They like a temperature of 72°-82°F (22°-28°C) and a pH of 6.0 – 7.5. The also need 5000 – 7000K (this is common for most plants, it is important to mention it).

Water Wisteria

Water Wisteria takes care of itself. You do have two options when putting it in your aquarium, plant it or let it float. I don’t recommend changing after you’ve decided though. They like a temperature of 74°-82°F (23°-28°C) and a pH of 6.5-7.5. The also need 5000 – 7000K.

Cabomba (Maybe)

I’m not sure this is what the plant actually is. It has been a complete mess since I got it. I planted it in the back corner of my tank, and it kept uprooting itself, and there were these little needles everywhere (actually clogged my filter). I decided to try floating it, and it’s working so much better. If you decided to get this plant I highly recommend floating it. It likes a temperature of 72°-82°F (22°-28°C) and a pH of 6.5-7.5. This plant requires high light at the 5000-7000K spectrum.

NOTE: I have read that the leaves dropping indicates insufficient CO2. This explanation makes sense considering that I was still working out my CO2 levels when I got it.


If you decide to get plants, you have two choices: tissue cultured plants or aquarium plants. The tissue cultured plants usually come in a plastic tube with a gel on the roots. These plants usually come with a guarantee “disease and snail free.” They are more expensive and have very short roots. The aquarium plants you see that some pet stores are healthier from the start, have longer roots but run the risk of having a disease and snails.

Diseases are obviously an issue, Ich being the most common, but can be treated if caught early enough. Snails, on the other hand, can be an endless struggle. The last plant I bought had snail eggs on it and, despite the fact that I attempted to clean the Cabomba (maybe) of any snails (short soak in disinfectant usually does the trick), their population is exploding.

For now, that’s all! There may be a part two later on.

Sources:,, experience

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