Nitrates won't go down!!


Reefing newb
I have been trying to get my nitrates to go down for months now. They spiked off the charts(200 or so) and since then I have gotten them down to 80 but no matter how many water changes I do I can't get them lower than this. There is nothing dead in the tank and I have been cleaning the filter pads almost daily. Any advice on what to do from here would be helpful, all my other levels are perfect it is just the nitrates. I also just added a lid last week in case there is something being sprayed getting in the air. The fish tank is at our office and I am not there all the time.


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Hi and welcome to Living Reefs!

What kit are you using to test? Have you tried testing with a different kit? The kits will go bad and give you false readings but if you are using that kit to test the LFS water and getting 0 this probably isn't the case here.
HI, welcome,
A little bit more info would be helpful. Size of DT and sump ? Stocking list, feeding regime and water change schedule please.
I finally got it figured out. My API test kit was wrong on the readings so I invested in a better test kit -Salifert.
Nitrates are certainly an issues in this hobby and one that is difficult to solve. Sounds like you have the nitrogen cycle under control as the ammonia is being converted to nitrites by the nitrifying bacteria and the nitrites are then being converted to nitrates. This is all a good thing since nitrates are much less harmful to marine life then either ammonia or nitrites. When I looked at your tank it appeared that there was not any growth of coraline algae on the rocks which lead me to think that the live rock may have been rock that was base rock or dried out live rock, if this was the case then there may have been an accumulation of dust on the rock and this needs to decompose just like food. Also am wondering if there is a protein skimmer on the tank, a protein skimmer can help reduce nitrates by removing some of the organics from the water that will also decompose. I also noticed that you have a shallow sand bed in the tank, my thinking and certainly not an expert but you should either go with a deep bed or no sand as a shallow bed does not allow for the anaerobic bacteria to grow in the tank which is benificial in the removal of nitrates as well. Suggestions: (1) install a protein skimmer or get a larger skimmer, (2) purchase a few good pieces of live rock that have coraline growth on them to seed your tank, (3) feed the fish a bit less to get the nitrates under control. and (4) do small water changes daily say one or two gallons to refresh the water daily until you start to see nitrates go down. I think if you do these things you will see that your nitrate problems may decrease to around the 5 ppm's or less.
@Old Tom I agree with everything you have said except the sand bed. I run a shallow sand bed it's only 2cm in depth. The secret to having a shallow bed is to make sure it is clean, lots of cuc & raking or siphoning often. I removed my deep sand bed from my sump on an upgrade & haven't looked back My nitrates are always undetectable , I believe my secret is running 2kgs of seachem matrix in my sump. And as you've already said nice light porus rock. Turkey basting rocks can also help a lot ( I do every week) so there is no detritus build up.