My plant tank has been set up for a couple weeks now. When I tested the water yesterday the readings were:

Ammonia 0
Nitrite 1
Nitrate 40

Should I do a water change to get the numbers lower? Or are those numbers Ok since there are only plants in the tank?

I know when the water should be changed for fish. But how do you know when a plant tank needs a water change?

Sorry I don't have any info to answer your question, but I have a question of my own for you....

Why are you keeping an aquarium with just plants in it?

Just leave it be. The plants will be needing the ammonia and nitrites to establish themselves anyway. (notice how the ammonia was zero? that's because plants crave ammonia the most, then nitrites, then nitrates, in that order). The nitrogenous compounds are what plants use to build up their cellular mass and grow.

You better have good lighting on your setup though. All that absorption of nitrogenous wastes requires heavy photosynthetic energy.

As for the waterchange frequency... if there's only minimal animal population in your tank, it's basically 35% once a week, as Takashi Amano does in his Nature Aquarium setups (but he uses canister filtration). If you plan to have more or bigger critters, maybe do the waterchange twice a week to play it safe

I was at an aquaruim society auction and on a whim I bought some plants. Crypocryne Becketi, anarachis, horn wart and java moss. I never keep plants before so once I got them home I had to figure out what to do with them. So I set up a 10 gallon aquarium with an aquaclear filter. So now I'm trying to learn about plants.

I have 7 other aquariums and room to set up more if and when I want to.




I have the tank in front of a window that gets full sun for a good part of the day.

Should I wait until the nitrites and nitrates drop before I start doing the weekly water changes?

yep. Just so to also help the microfauna in the tank establish themselves as well. Helpful bacteria don't like being disturbed too much