Looking for the Right Kind of Plant

[DainBramage1991]

I'm having an issue keeping the nitrates down in my densely populated loach tank. Yes, I'm a sucker for loaches and catfish, and I know better than to overstock my tank but I did it anyway. Oops.

I've got strong filtration, do frequent water changes, and monitor the chemistry closely. My fish, as far as I can tell, are healthy and happy.

Unfortunately, the usual permanent corrective options (larger tank, multiple tanks, automatic water changers, etc.) are not available to me due to space and budgetary limitations. Not having a green thumb (plants hate me), I've only recently tried adding some live plants. The vallisneria, which I acquired for free from a kind friend, has spent more time clogging up my filter inlet than staying rooted in the substrate.
It doesn't help that the yoyos are constantly digging up the roots, and all of the loaches seem to consider it a salad bar.

So it's back to the drawing board.

Here's what I'm looking for:
A floating plant (so that it won't be affected by digging), that isn't appetizing to loaches (so it doesn't become dinner), that's self-sustaining (because I have terrible luck with plants), that absorbs nitrate quickly (that's the main reason I want it), is relatively inexpensive (there are those pesky budgetary limitations again), and is readily available in the northeastern US (and legal, of course).

Am I being too picky?

[Diana]

Duckweed
Floats at the surface.
Great Nitrogen sponge.
Easy to harvest.
Most fish do not eat it, but I think some Barbs and Goldfish will eat it. None of my Loaches seem to eat it.
Aquatic weed. Difficult to get rid of 100%.
Accepts lower light than many plants because it floats right under the tank light.
Gives you little green dots every time you stick your hand in the tank.

Java Fern, Java Moss, Anubias
Grow any of these tied to a rock or driftwood. Do not root them in the substrate.
Slow growing, so not a great n-sponge.
No need to harvest, though you can.
Most fish do not eat the Java Fern or Anubias. Some fish will tear up the Java moss.
Slow growing, so not weedy.
While these are low light aquatic plants, they are growing under the water surface, so I would suggest at least 1.5 watts of light per gallon.

Anacharis/Elodea
Several species.
Drift in the water, including at the surface. Some people put a rock on some stems to hold them to the bottom. Do not really root in the substrate.
Very fast, great N-sponge.
Easy to harvest, easy to get rid of if you get tired of it.
Many fish eat some or all these species.
I would suggest at least 1.5 wpg, or more (at 2 wpg these plants grew better for me.)
Some species may be restricted in some places.

Hygrphylla polysperma 'Sunset'
Fairly fast, but needs more light.
Pretty descent H-sponge.
Best rooted in the substrate, but my Dojo keeps stirring the substrate, so my 'Sunset' is drifting.
Not legal in all states.

Water Hyacinth
Best as a pond plant in something close to full sun. Very bright aquarium light, open top. These plants float, and grow at least 6" above the water, then the flower stem is taller. (about a foot)
The best N-sponge, if you can keep it happy.
Fish do not eat it.
My not be legal everywhere, but you may be able to find it growing wild (invasive) in areas where the water does not freeze. It grows here in northern CA.

Water Lettuce
Best as a pond plant in about 1/2-3/4 day of sun. Very bright aquarium light, open top. These plants float, and grow at least 4" above the water, and 6" is more like it (in my pond).
Very good N-sponge, if you can keep it happy.
Fish may eat the roots (my Golds had it nibbled down to practically no roots) but they do not eat the leaves.
Not legal everywhere. It will die if it freezes, and does not quite keep going over the winter here in N CA, but is invasive in southern CA.

Other plants (such as Valisneria and many others)
Try growing them in a pot, or open basket sort of container. Fish cannot tear up the roots (large pebbles on the surface of the pot).

[Jules]

Indian Fern (Ceratopteris thalictroides) is excellent for absorbing nitrates.

You can also use it as a floating plant as well as planted. Likes bright lighting but is fast growing and needs to be kept 20-26C. App floating plants are the best for cutting down on the nitrates as they aren't limited by CO2 as they take it from the air. I had some Salvina Natans but it quickly took over the tank and I got fed up with it hanging on every time my hands went into the tank.

Polyfilter will also help as would using RO water. Just some thoughts....

Hope this is useful to you.

[surgeon]

Amazonian frogbit is another floating plant that grows fairly quickly (though not as fast as duckweed, nothing grows faster than that damn stuff). I can also vouch for java fern, some crypts and hygro.

As far as nitrates go my best advice is to look at making your water changes easier with long hoses or something. I do a 50% water change weekly and have done so for years. A couple of degrees drop in the water temp wont hurt your loaches (just think what the river turns into in a partculalry bad storm).

[DainBramage1991]

Thanks for all of the helpful replies! I will certainly look into these various options.

As for using RO water, I've considered it but it's not necessary here as our community water is very good. As for temperature drops from water changes, I have a secret weapon I use to prevent that: a high precision thermometer left over from my old career. I run the new water into the tank within 1 degree F of what it came out at (76F). I know that a couple of degrees won't hurt the fish, when I was younger I used to gauge water temp by feel and was often inaccurate by quite a bit. But I like to reduce stress whenever possible, especially since I'm doing water changes once or twice a week these days.

A few clumps of vallisneria have managed to survive the better part of a week now, perhaps they will start to thrive if the yoyos leave their roots alone. If not, I've got some alternatives to consider.

Thanks again!