Dumb, long nitrate question

Hi all,
Sorry for the long question/update. I can't remember how long I've had my tank now, I think since December. I've had a bunch of issues including ich, random deaths of one fish at a time while everyone else seems fine, and most recently some weird illness that kind of looked like lymphocystitis but not quite, or fungus but not quite, and affected only my black neons. Etc. etc. Things seem stable now, the ich cleared up with Paraguard treatment, the black neons are much improved and seem to be improving all the time, after Sulfaplex treatment, no one has died in a while, etc. I returned 3 Danios to the store that were too intense for the other fish, got more female Platies to improve the ratio of males to females, etc. in an attempt to reduce stress, and it seems to have helped; some of the more timid fish are not hiding so much, and the vibe is less frenetic.

During all this drama I was doing frequent, pretty high volume water changes since everywhere I read that keeping the water quality high is the best thing for sick or stressed fish. So I hadn't bothered testing parameters in quite a while.

Today for the first time in weeks/months it has been 3 or 4 days since I changed the water, so I thought it would be a good time to test (using an API Master tet kit). I'm showing 0 or slightly more than 0 but less than 0.25 (I find it hard to discern the color exactly) ammonia, 0 nitrites, and 0 nitrates.

So my question is, shouldn't there be some nitrates? I was very precise with timing, drops, etc. to make sure it was accurate, but this doesn't seem normal.

I have a 40g breeder planted tank with 3 black neons, 3 neons, 6 glowlight tetras, 2 oto catfish, and either 6 platies or 3 platies and 3 mollies that I *thought* were platies when I bought them. And 5 or 6 babies, I'm not sure if they're platies or mollies, still very tiny.

On a side note, I'm planning to also set up a 25g tank and switch some fish around and get a few more black neons, neons, and otos so they have more robust schools, add my Betta and blue mystery snail to one of the big tanks, and use the 7.5g tank those 2 are currently in as a quarantine/hospital tank. But I'm not going to mess with the 40g residents any more for at least a couple weeks, so they have a chance to fully stabilize/recover from all the stress.

 

Thanks for all the feedback! I wasn't thinking plants could use up the nitrates. To be honest I don't understand the chemistry or how fertilizer works, etc. Sort of like math, I understand how to do the problems but I have no idea what it all means. LOL I just started adding some Seachem Excel for my plants since I thought they might need help, they looked a little pathetic, and I read a few people have found that it helps reduce algae, which I was also having quite a lot of trouble with...It's better now, but I figured Excel might be a good idea.

I'm using the API Master test kit. I followed the instructions I think to the letter, but I don't remember needing to shake the solutions before using them; I will do that next time. I did a major clean up of the gravel and water change yesterday so I will give it a couple days and test again to compare. It seems like the gravel gets really dirty, probably from overfeeding. And the plants are always shedding dead bits. And the Mollies (?) seem to poop like crazy. Perhaps because they are getting most of the food, as they are pretty pushy about it at feeding time.

 

By the way, it's interesting, in the past week or so it seems like the tetras and my Mickey Mouse blue platy have much richer color now. The neons are especially vivid. Not sure if this is due to reduced stress, or adding what I think is better quality food (Omega One flakes) and mosquito larvae--perhaps they are responding positively to that? At any rate it seems like a positive sign!

 

Thanks, Dougall. That would be good if Excel helps with algae on the plants, they have had a lot of brown algae which I'm sure is making it difficult for them getting light, too. I will shake the heck out of the bottles next testing session!