help with nitrates.

[Nimo]

My brotherinlaw has a salt water tank that has gone crazy due to a bad test kit. He kept having problems with his fish but his tests were all reading good. I went to his house and checked things with my kit and found that he had
Ammonia .50
Nitrites beyween .50-1
Nitrates 160 or more I have never saw the nitrate that red.
This tank is 25-30 gallons he cant remember. We did an immediate 50 percent water change. Followed by another 50 percent water change about 2 hours later. Got the Ammonia down to 0 and the nitrites down to 0. He has been doing 25-30 percent daily changes for about 4 days now but cant get the nitrates out of the hundreds.
He bought a new kit and we have tested sode by side getting the same results on his tank. He has used his new kit to test my tanks to see if his was just reading high. My tanks are always 20 or less so his test kit is now reading correct but cant seem to get the nitrates to come down.
Sorry for such a long post but I wanted to give as much description as possible. Thanks ahead of time for any advise that I might be able to send to him to help.

 

[Phranque]

Well, if there's any presence of ammo & nitrites, the tank isn't cycled yet, or something happened that caused a mini-cycle......

How old is the tank?
What kind of filtration is he using?
What is the livestock?
How often & how much does he feed?
What kind of substrate?
Does the substrate occasionally get vacuumed with water changes?


If it is an established tank, I'm going to take a very wild stab in the dark and guess it's an overstocked & overfed tank with a shallow sandbed that hasn't been vacuumed in a while, and a canister (or HOB) filter that is way overdue for a cleaning...... Any of these situations alone will cause higher nitrates, but all of them together will create an out of control freight train.

 

[Nimo]

Established tank about 5 years old. Only a dotty back goby and a 6 line wras stocked now has had a couple deaths. Sand was cleaned and filter was cleaned when the first 50 percent water change was done.
I was thinking change the sand all together and replace it with new.
He also had a bad test kit that was giving false low readings so he didnt realize how bad the water quality was.
Could be over feed too. His mom was feeding the fish for a while for him while he was out of town.

 

[Phranque]

Keep at the water changes..... with just cleaning the sandbed, especially if it hadn't been done in a while, could've released a lot of decaying material that will take a little while for the system to digest. Also, in a tank that small, anything dying & not removed right away will spike up the nitrates pretty quick..... so if he had some die off, that wouldn't have helped matters.

 

[Nimo]

As far as I know the dead were removed quickly. And I have told him to continue the water changes while I ask around for any other advice. He doesnt have access to the internet or I would refer him to this forum.

 

[Bray84]

I read something about 50% wc only takes 10-20% of the nitrates out water but don't hold me onit when I first started my tank as my test kit was reading hit but lfs test was good so got new kit