Please help with high nitrates

[scuba_steveo]

I just received the following email. Please help with the advice.

sorry to be bothering you but you are about the only one person i have met so far that is knowledgeable in my very annoying problem. my problem is in my tank i have a 135g and the last water change was about 2 weeks ago. i did a test then and now and about every week or so just for good measure. my PH is anywhere from 8.0-8.2 and the nitrite is 0-.25, ammonia is 0-.25 but my problem comes in to be the nitrate for the past three to four months i cant get my nitrate below 160ish my fish are swimming fine and eating very well but i just dont like it being that high. everyone i have talked too say that it needs to be less than 40. i have done big water changes like 40-50 gallons. and i have done little water changes like 10gallons every few days for a couple weeks. i have used the nitrate chips and it still hasnt helped. they have been in there for about a month now. my 29 gallon all the levels are great. so i dont know what i am doing wrong in the big tank. we have a wet dry filter, 18 watt turbo twist uv sterilizer,and a protein skimmer. Right now in the tank i have about 100 pounds of live rock and i am cureing another aprox 125-150 to put in there. most of it is done i think cause the rotten oder is gone. i have been told that i should get a small refugium to help bring the nitrate down but i want some advice from someone who i belive actually has a clue. thank you for taking time to read this and giving somebody some well needed advice.


thank you for your time

[scuba_steveo]

Here is my response:

Sure I remember who you are. Yes, the high nitrate battle. I am going to copy your email into MAAST for more help. Fish can tollereat this, corals cannot. Have you taken a water sample to a fish store to be tested? Or is that your home test kit? I agree with the refugium. I think they are very beneficial to an aguarium. Almost as much as a skimmer. And you need a big refugium and a big skimmer. My buddy has a mixed reef. So he has corals and agressive fish. The agressive fish are very messy eaters and big ****ters. So he has levels higher than he wants. He has a refugium but not very big so he is going to build a bigger one. How do you skim? Does it come out dark in small amounts or light in large amounts. Light in large amounts is called skimming wet. You should do this. You remove more waste this way. All you have to do is turn your skimmer up to allow more air in and more output. But you will lose saltwater this way so you need to top off with RO sometimes and saltwater other times to keep the salinity in check. If your skimmer is not that big, get another. And build the biggest refugium you can. Get Dan or Pete to custom make it. And continue with the water changes, big ones.

Quick side note about water changes. You have 135 gallons at 160 nitrate

If you do a 50 gallon water change that is 50/135 = 37% water change = 63% old water remaining

160 x .63 = 101 nitrate = still way too high

do not bother with any water change less than 50 gallons and try to do even more. Bump it up two twice a week until you get it under control

Hope this helps,

Steven

[GaryP]

Overfeeding may also me an issue. Does this person have a DSB or other areas with an anoxic zone for denitrification? I'm guessing no, otherwise there wouldn't be this large of a buildup of nitrates. I would verify these numbers, as you suggest by an LFS to make sure its just not a testing issue.

[NaCl_H2O]

WOW, 160 Nitrate - I have never seen anything close to that! Actually, the Amm & Nitrite are fairly high too, and thus feeding the accumulation of Nitrate.

More live rock may help (100lbs is nothing for a 135), if it is REALLY cured, and a DSB as Gary suggests ... but not before it matures for a month or so.

I would suspect he is overstocked & overfeeding - how many fish are in his 135g?

He mentioned a Wet/Dry, which I assume has some type of mechanical filter above the Dry portion. Is he changing the filter floss on a regular basis?

[gjuarez]

How long has he had his tank? Does he maintain his sand bed? There is a lot of questions that need to be answered before the problem can he diagnosed.