3 water changes, still high nitrate


New member
I've had a 125 with a 40g sump running for a few months now. I transferred everything over from a 29 biocube and added a few more fish. I had internal parasite problem so I dosed prazipro in the DT. I started testing the water because I turned my skimmer off during the treatment and I realized my nitrates were 40-80.

I left it alone until the treatment was done knowing that I'd have to do some water changes to get the meds out. I did 3 20g water changes (one a day for 3 days) and my nitrates are still around 40. What the hell do I have to do to get them down?

My tank as of now is:
Ammonia: 0
Nitrite: 0
Nitrate: 40-60
Ph: 8.2
Temp: 79.5
Skimmer: reef dynamics 180E
I have cheato in the fuge but it hasn't grown in a while (it's not dying either though)

Stock is 2 clowns, six line, 3 bartlett anthias, royal gramma, yellow tang and a powder blue. I did add 2 cleaner shrimp a few weeks ago, but I haven't seen them since my nitrates got up to 80 (I pretty much know they're dead, but I can't find them).

What can I do to get my nitrates down? I know water changes are supposed I work well, but I've done 3 and I can. Get them below 40.


Active member
You'll need to do a much larger water changes if your looking to drop nitrates down fast. On the order of 50%, a few days in a row.


New member
3 water changes, still high nitrate

uhg I don't have a bin that big, and my rodi only puts out 75 a day. I thought smaller changes more frequently were better for everything in the tank. If I do jeep the water changes up (1 or 2 20g a week) will the nitrates drop eventually? Could the MIA shrimp have anything to do with this?


New member
It'll just take time with small water changes.

From your current water changes you are probably only changing around 15% or so each change (20/130) or so. An estimate from your system actual water volume.

So if you started with 80ppm:

At the same time your tank would also be generating nitrates. I say keep doing the 2 20gallon water changes per week. In about 2 months you should be 10ppm or under.

Just keep with it, as long as you don't get hit with algae you can keep doing smaller water changes as you have been doing to lower nitrate. Your right, large water changes can shock inhabitants due to perimeter changes.

Dead shrimp can certainly add to high levels. In a 125 gallon tank the addition shouldn't too high however. Give it time, I've "lost" critters in my 29bc only to see them months later. I've heard many similar stories.


Premium Member
You can try the smaller water changes. If they don't work, the tank is generating nitrate at too high a rate. I agree that a couple of dead cleaner shrimp, if they are dead, likely wouldn't spike the levels all that much.


New member
If you had a lot of worms, and/or parasites, there's a possibility killing off the parasites and the worms added to your nitrates (or still is). Prazipro I've heard good things about for killing parasites, however, it also kills beneficial fan worms... (the little white ones that tend to accumulate every where...)

If you have a lot of critters like that, that could add to the problem. Try a different test kit too to make sure. But, other than that, what everyone else said. :)


New member
Yeah I was thinking about picking up another test kit this weekend. I'm using the API one now and I'm just finding it hard to believe that my nitrates are that high. All my fish are small and I have a huge sump with an oversized skimmer.