Can Plants Give False Nitrate Readings?

Hello all, I have a 10 gallon tank with a large Amazon sword plant, a medium(ish) El Niño plant and 4 medium gold ribbons. The tank is cycled and has a tiny fantail goldfish in it (I have a 40 gallon cycling right now don't worry it's only temporary). It has a filter meant for a 20 gallon. I do a gallon water change every other day instead of just a 25% weekly so nothing bad gets a chance to build up. My tests on the tank confuse me though. Ammonia and nitrite always read 0 but my nitrates never even reach 5ppm. Are the plants actually using all of the nitrates or am I just doing so many water changes that I never have nitrates? Or are they somehow giving me a false reading? It's not the testing chemicals because they read right for all of my other tanks. I just don't understand how I can have water with that great quality in a tiny tank with a goldfish in it

 

I would guess it's more of the plants that's causing those parameters. Especially the amazon sword because if it's big, then its root system is probably big enough to take up a lot of waste from the goldfish. When you combine large plants and more than regular water changes, that could explain it.

 

I’m not sure it’s the plants, unless you have fast growing water-column feeders. If it’s one little goldfish, then it makes sense. Sure they poop a lot, but that doesn’t always equate to high bioload. That is as long as you’re not overfeeding. I suspect that a lot of the poop is coming from the fact that they also filter feed from the water column and pick at algae. I’ve had goldfish still poop loads after fasting them for seven days, but the water parameters were good, because they weren’t feeding on anything rich (like fish foods), and simply foraging naturally on algae found in the tank. Goldfish are detritus eaters, so in the wild they’re used to eating decaying matter with little nutrition, but compensate that by eating lots of it.

 

If you’re using the API master test kit, the nitrate test is prone to error if bottle number two is not shaken really really really well.
I almost always have to run the nitrate test twice, because even though I beat, shake and torture the second bottle into submission, my first test gives 0 nitrates, which I know ain’t right. When I do the test a second time, I get a more realistic number.

 

If you’re using the API master test kit, the nitrate test is prone to error if bottle number two is not shaken really really really well.
I almost always have to run the nitrate test twice, because even though I beat, shake and torture the second bottle into submission, my first test gives 0 nitrates, which I know ain’t right. When I do the test a second time, I get a more realistic number.

Yeah that's what I use. I always shake the bottles a little but I'm gonna start shaking the second one really well from now on. Thank you so much!

I would guess it's more of the plants that's causing those parameters. Especially the amazon sword because if it's big, then its root system is probably big enough to take up a lot of waste from the goldfish. When you combine large plants and more than regular water changes, that could explain it.

Yeah that's what I thought but wasn't completely sure about. Thank you!

I’m not sure it’s the plants, unless you have fast growing water-column feeders. If it’s one little goldfish, then it makes sense. Sure they poop a lot, but that doesn’t always equate to high bioload. That is as long as you’re not overfeeding. I suspect that a lot of the poop is coming from the fact that they also filter feed from the water column and pick at algae. I’ve had goldfish still poop loads after fasting them for seven days, but the water parameters were good, because they weren’t feeding on anything rich (like fish foods), and simply foraging naturally on algae found in the tank. Goldfish are detritus eaters, so in the wild they’re used to eating decaying matter with little nutrition, but compensate that by eating lots of it.

He only gets 5-6 omega one small goldfish pellets a day and he's always picking at the plants. I also feed him spinach and cucumber every time I get some. That's really good to know I've always just assumed that since he's a goldfish he's gonna try to kill himself with his own poo haha. Thank you so much!

 

Plants use straight ammonia (before it gets converted to nitrates) competing with bacteria.
If the bioload is low and plants are actively growing, results could be real, not false.

 

Plants use straight ammonia (before it gets converted to nitrates) competing with bacteria.
If the bioload is low and plants are actively growing, results could be real, not false.

I didn't know that I thought they used the nitrates. I'm going to research that now. Thank you for telling me that I had no idea! Me and my fish really appreciate it

 

Plants use nitrates also but they prefer ammonia if available since nitrates must be reduced to ammonia and then to ammonium to be utilized.

 

My planted tanks always have 0 ammonia, 0 nitrite, and 0 nitrate. I can dump in tons of food, but the plants eat up the ammonia and nitrate like crazy.

 

My planted tanks always have 0 ammonia, 0 nitrite, and 0 nitrate. I can dump in tons of food, but the plants eat up the ammonia and nitrate like crazy.

That's pretty much what's going on in mine I guess

Plants use nitrates also but they prefer ammonia if available since nitrates must be reduced to ammonia and then to ammonium to be utilized.

That makes a lot of sense. Thank you!

 

Yeah that's what I use. I always shake the bottles a little but I'm gonna start shaking the second one really well from now on.

I’d try a couple of double tests, just to be sure this isn’t an issue. So, even though it’s plausible your nitrates are being grabbed by the plants (or not even being created, if the plants are intercepting ammonia), test nitrates twice, consecutively. Ie test once, then test again after the first test is complete. If u get the same result you will know empirically that this isn’t an issue (and you’ll be a better nitrate tester than me LOL).

 

I’d try a couple of double tests, just to be sure this isn’t an issue. So, even though it’s plausible your nitrates are being grabbed by the plants (or not even being created, if the plants are intercepting ammonia), test nitrates twice, consecutively. Ie test once, then test again after the first test is complete. If u get the same result you will know empirically that this isn’t an issue (and you’ll be a better nitrate tester than me LOL).

That's what I usually do just to be sure haha. I usually test for nitrates with all four vials and they always come back with the same result in all four. Thank you for replying!

 

Shake that #2 bottle like it owes you money.

 

That's interesting to know because I don't think plants could do that. I agree that the fishes might be more responsible.