Large nitrate fluctuations

Dirtyshoez · Dec 20, 2025

I've been battling my Nitrates for a couple of weeks and so now I have questions..

My tank is about 4 months old and has been going through the normal stuff, and I do my fair share of reading and thinking to see if or what I'm missing in the equation.

One thing I wanna point out but doesn't really line up with this obstacle starting is I am missing a fish but maybe missing for about a week now.

So end of last month I noticed my nitrates creeping up from the usual 5 range it would stay around. Noticed 8.1, noted, next day 8.8, (hmm), then 9.5... (ok, let's tighten up on feeding) I admit I need to tighten up on feeding. So I did... 10.1, and 11. Said screw it and did a water change. Next day 9.2, then 8.7.. Then 5. Was thinking ok awesome, stick with my regiment and right back up to 11s and then 6 and back and forth on a day to day... have done multiple water changes and 1 change didn't even touch it for about 2 days and then the fluctuation again. So yesterday I did a change and this morning 13's... so afternoon i vacuumed detritus in sump and did 30gal change in there as well. I am hoping I see a change in pattern here but I want to know what I may be missing. Does the ugly stage have a play in this obstacle? Is lighting a probability if the lighting cycle is the same and has not been a changing factor. I reeled in the feeding. And now I have cleaned the sump. I have also been dosing microbacter clean in the evening and consistently cleaning the skimmer atleast twice a week (it's definitely pumping some ****). Am I hitting all the stops and just need to stick to my guns till it levels or what am I missing? Thanks

Mr. Mojo Rising · Dec 21, 2025

Fish food plus fish poop = nitrate +/- the filtration capability.
Can you give us more info on the tank size, livestock, how much you feed, filtration, amount of rockwork, do you have a sandbed in the tank, how is the flow in the tank, which test kit are you using..... all contributes to increase or decrease nitrate, so we need this info to help you.

Dirtyshoez · Dec 21, 2025

Sure. I have a 200g with a about 150lbs of sand and about 120lbs of live rock plus a large media rock in the sump, skimmer, large reef mat, 48w UV, about 55 snails/crabs (cuc) 2 tangs, 2 wrasse, 2 clowns, 1 chromis, 1 blenny, and 3 firefish. Both tangs are juvenile. I feed them about a cube of mermaid delight with a mix of rods a day. And 1 to 2 sheets of nori. Testing nitrate and phosphate with Hanna checkers, do weekly water changes of 30 gallons and clean my skimmer 1 to 2 times a week, and a total of 5 gyres in the tank plenty of flow... as of today im going to put a cheap powerhead in the sump to see if that helps some.

Dirtyshoez · Dec 21, 2025

I also broadcast 2x a week and direct feed once anything that can use it.

Randy Holmes-Farley · Dec 21, 2025

I was expecting a bigger change from the title. I would not worry about, nor try to explain every small movement. IMO, nitrate at 5-50 ppm is fine. :)

Dirtyshoez · Dec 21, 2025

Randy Holmes-Farley said:
I was expecting a bigger change from the title. I would not worry about, nor try to explain every small movement. IMO, nitrate at 5-50 ppm is fine. :)

Fair enough... I guess as the tank begins to mature I'll see this type of flux more and more? The changes are fairly new but the tank has been doing good overall just want to make sure it continues

Randy Holmes-Farley · Dec 21, 2025

Dirtyshoez said:
Fair enough... I guess as the tank begins to mature I'll see this type of flux more and more? The changes are fairly new but the tank has been doing good overall just want to make sure it continues

Some changes might be test variations too. I’d just watch the trends over multiple tests and take actions if you see it going out of your target range. :)