Pothos and Other Plants for Nitrate Reduction

[zackcrack00]

I thought a few have tried using certain plants such as pothos and water sprite in their tanks to reduce nitrate. Does this work? Do some plants actually use significant amounts of nitrate/ammonia, enough to make their incorporation into the tank or its filter worthwhile?

My (heavily) overstocked 20L growout's ammonia levels never show, but nitrates are a big problem. I've been doing 50%-90% water changes daily, and nitrate still tests at 40-50ppm or more the next day. The nitrate levels of the water added during the changes have been 0 the two times that I've tested.

I've added some anubias, java fern, anacharis, dwarf hairgrass, and even a handful of widgeongrass thus far; but I thought I remembered a few CCA members talking about using pothos at one point or another.

 

[chriscoli]

So, there are a few things to keep in mind:
- most plants in the tank actually don't like nitrate, but they do a great job at using ammonia, which ultimately results in less nitrate.
- there are a few plants that like nitrate. hornwort under a lot of light does, as well as some terrestrial grasses (they are large grasses that need full sun)
- fast-growing plants will use more nutrients than slow growing plants- so things like guppy grass, hornwort, etc.
- more light = more growth
- CO2 is usually the limiting factor with submerged plants, so emersed plants (growing above the water) have the advantage that they don't have the same CO2 limitation. which is why pothos is often recommended. it's fast growing when it's happy, and easy to find. I've also used spider plants in the past. If you are going to use emersed plants, make sure they get enough light.
- I've found that eventually, pothos will run out of other nutrients in the tank, so it occasionally will need a boos of some micronutrients to keep it happy (something like Flourish).

 

[zendog]

I can't say how it does at removing nitrates specifically, but I usually have a layer of duckweed (sometimes salvinia or mixed with salvinia) on my fry tanks. I don't have to worry about the C02 issue or it getting enough light, since it is on the top and when it gets too thick, I just scoop a bunch out and throw it into my house plants as a quick mulch.

I believe since it grows so fast, duckweed is good at removing excess nutrients from the water. I also keep rams horn snails in my fry tanks to remove any extra food the fry miss, plus some java moss just for something for the fry to pick on between meals. I don't think the java moss does much in terms of removing nitrates.

I've got no science to back this up, but it has worked okay for me. I also don't test my water much, but I expect more water changes would help my fry grow faster but I just don't have enough time to change water daily.

The downside is duckweed gets on you every time you put your hand or anything else in the tank.

 

[mchambers]

I had pothos growing in a couple of tanks for a while, but I never tested nitrate levels. If you try this, it would be best if the tank were near a window so the pothos could get natural light.

I agree with Christine and Walter that the best approach is to have fast growing plants.

 

[chriscoli]

I agree with Walter about the duckweed. I know a lot of people hate it, but every time I net a glob out of my tank I call it "nutrient export".

I put my unwanted duckweed into my red wiggler bin.

 

[JLW]

Duckweed is the best plant at reducing nitrates, provided you remove it regularly. If you don't remove it, it reaches a critical mass, and just dies and grows at an equal rate, thus no nutrient export.

 

[FishEggs]

Duckweed can also make a good shrimp food.

 

[CichlidAddict]

An alternative to duckweed is frogbit, a large version of duckweed and less sticky.

 

[b considine]

Damn duckweed. I've got a plague of it.

To stay on topic, Christine's post up top is solid advice.

Blaise

 

[zackcrack00]

Thanks for all the advice! I’ve put some pothos in some marina Breeder boxes with fry and they seem happy, one plant already has a few new leaves.

- there are a few plants that like nitrate. hornwort under a lot of light does, as well as some terrestrial grasses (they are large grasses that need full sun)
- fast-growing plants will use more nutrients than slow growing plants- so things like guppy grass, hornwort, etc.
- more light = more growth.

Christine, I’ve tried hornwort, cabomba, and even ambulia multiple times but to no avail. These finer-leaved, bushier plants just seems to hate every tank I have! Instead, I’ve added lots of java moss in some of the Breeder boxes and the fry tank. In the problem tank, my 20L growout, I’ve added a menagerie of plants including emersed pothos, java fern, anubias (mostly for looks), ludwigia, Mini Dwarf Hairgrass, Riccia, wisteria, rotala nanjenshan, and H. polysperma. The nitrates have already dropped slightly, and I’m expecting them to continue to do so once the plants get accustomed to my water conditions and get some nice roots.