Changed Water And Nitrates Are Higher - How Come?

[purrsian]

Just recently, I've had two fish die - a neon and an albino rainbow shark. Because I can't totally tell why they died, I've finally bought myself a nitrate test kit, soon to be followed by a few other tests when I can afford them. Tested the water yesterday and it was pH of 7.2 and nitrates of 7ppm. I did a water change that afternoon, let the water settle and all and I've tested the water again today. The pH is 7.4 and nitrates are 10-12ppm.

I thought water changes were supposed to drop nitrate levels?? Is this normal and if it's not, does anyone know why it might be happening??

Thanks for any help!


Just so you know, it's a 16 gallon tank with 4 neons and 1 lemon tetra. There's a piece of driftwood in there and one live plant that isn't doing well but never has because of the snails. The tank is over 2 years old, probably almost 3, and I haven't had any problems since we moved house about 2 years ago when we lost a couple of fish in the first few weeks.

 

[purrsian]

Also if it helps I tested my tap water today and it was pH 7.6 and nitrates between 0 and 5ppm. I don't know if that has anything to do with anything but hey, might help

 

[Bignose]

what nitrate test are you using? None of the tests in most LFSs can be anywhere near as accurate to know that there is a real difference between 7ppm and 10ppm. If it is a strip test, those are notoriously inaccurate, and if it is a drip test, are you sure that every drip was exactly the same size? No, because that is reasonably impossible to be 100% sure. That 3 ppm difference is completely within the margin of error.

That said, variations in tap water do occur all the time, and one day it may be 20 or so ppm, and another 10 ppm. That just occurs.

Finally, having nitrates around 10 ppm is very good, that is a very low concentration. The fish should not be affected at that concentration. If you really think it is a concern, buy some fast growing plants. Hornwort has a repuation for being a nitrate sponge.

 

[purrsian]

Oh ok awesome. It's a drip test and on the little chart, it has 0 as yellow, 5 as yellowy orange and 10 as orange, reason I said they were 7 and 10 is because the colours definitely were different, but I suppose yes, it's probably just inaccuracies or the tap water being different. I was mainly just concerned because of the problems I've been having lately in my tank. Thanks for the help