Nitrates through the roof!

tookyfl

New Fish
Jan 7, 2018
3
0
1
#1
Hello! I am completely baffled... I have a 75g freshwater aquarium with one Fluval C4 HOB filter and one Fluval 406 canister. My nitrates are through the roof (160ppm) no matter what I do... They have been this high for months and months... maybe a year.

After attempting the normal stuff to reduce nitrates like filter maintenance, big water changes, chemical filter media (Purigen), etc, I decided to go extreme.

I did 50% water changes for 3 days in a row with EXTENSIVE substrate vacuuming. No change (in nitrate levels). I cleaned and changed filter media in my Fluval C4. No change. I removed all substrate and replaced with gravel along with two water changes in same day (over 50%). No change. I changed all filter pads and extensively cleaned Fluval 406 (kept Seachem Matrix bio media). No change. I did another 50% water change. Still no change in nitrate level.

The tank looks crystal clear perfect. The fish are doing excellent (despite all those drastic changes). I am struggling to get the nitrates under control as I don't want to have the algae problem I have been dealing with in the past.

I have Seiryu stone (or maybe Ying Stone) in the tank... I didn't think stones could leach nitrates?? Could it possibly be the stone? Any ideas would be GREATLY appreciated!
 

FreshyFresh

Superstar Fish
Jan 11, 2013
1,337
23
38
East Aurora, NY
#3
Are you showing nitrates right out of the tap?

What test kit are you using? It's super common for folks to not perform the nitrate test correctly with the API master test kit. Gotta shake the crap out of bottle #2 before you use it, then shake the heck out of the completed test tube for 1min, then let the tube sit for 5min before reading.

Reason I ask about your test procedure is, if you measure 160ppm nitrate before a water change and you change 50% of the water (assuming your tap water is 0ppm nitrate), the test after the water change should be 80ppm.

50% is about the smallest amount of water I change. I have an oscar and a green severum in my 75%. I dump the water until the fish start flopping over onto their sides. It's probably an ~80% WC.
 

tookyfl

New Fish
Jan 7, 2018
3
0
1
#4
Are you showing nitrates right out of the tap?

What test kit are you using? It's super common for folks to not perform the nitrate test correctly with the API master test kit. Gotta shake the crap out of bottle #2 before you use it, then shake the heck out of the completed test tube for 1min, then let the tube sit for 5min before reading.

Reason I ask about your test procedure is, if you measure 160ppm nitrate before a water change and you change 50% of the water (assuming your tap water is 0ppm nitrate), the test after the water change should be 80ppm.

50% is about the smallest amount of water I change. I have an oscar and a green severum in my 75%. I dump the water until the fish start flopping over onto their sides. It's probably an ~80% WC.
I'm using the API Master Test Kit. I follow the directions exactly (as you stated)... shaking bottle #2 vigorously for at least 30 seconds and then the test tube vigorously for at least 60 seconds.

I've tested my tap water... and it's about 5ppm (which lines up with what the water company reports in their water quality lab reports).

I also used Tetra EasyStrips which basically support the findings of the API test.

I know the nitrates should respond in a 1-to-1 ratio with water changes-- meaning a 50% water change should reduce nitrates by 50%. I have NEVER seen nitrates respond to my maintenance efforts.
 

FreshyFresh

Superstar Fish
Jan 11, 2013
1,337
23
38
East Aurora, NY
#5
The only times I've heard of this happening is if there was a dead fish trapped somewhere out of sight, the substrate had loads of junk buried in it, or a very clogged and dirty filter would pump a bunch of nitrates into the water once it's fired back up after the WC. Thing is, you've addressed these items.

I do know that if your source water is disinfected with chloramine as opposed to chlorine, chloramine breaks down to ammonia with your dechlorinator. Your tank's nitrogen cycle will then obviously break that ammonia down into nitrate.

Other than that, it's not chemically possible to do a 50% WC and not see a nitrate drop. Like you said, if your source water is 0ppm, that drop in nitrates should be by 50%.