nitrates are driving me up the wall

[mike31154]

Yow, 25-30% water change per week, that's heavy duty. I do the same percentage but only about every 16 to 21 days. Why not start monitoring nitrate levels closely at the time you would ordinarily do a water change and extend a few days to see what happens? Take it one day at a time after that and if it gets out of hand, then do the water change.

Are you running the system with a sump? You mention bottled water, is the source reliable? Might want to do a quick TDS check on your source water, although you say there is no algae in your tank.... maybe that's the problem, algae takes up nitrates quite efficiently, but of course the wrong kind is a pain.l

[i have crabs]

you said you have no filter media correct?, so no filter socks/sponges/floss/bioballs anywhere in the system? how much rock do you have in the tank? pictures amuse us and it might help us see what your workin with.
sandbed? how old is the tank?
test the water your using for waterchanges and your tank water to compare the 2, under 20ppm nitrate isnt a death trap but can add to other issues, i dont think your tank is over stocked, the only time ive had lingering nitrates is when i employ some kind of mechanical filter since i tend not to keep them clean enough,i feed frozen mysis,reefroids,cyclopeeze daily, i rinse out the mysis and make icecubes with everything mixed in that way its ready to go and pre portioned, since i started doing this im much better at not over feeding, i never have any problems nitrates in my reef and i think i still feed quite abit over all. i have quite a bit of live rock and a decient sized skimmer but thats it for filtering. i do 25-30% change ever 4-6 weeks in my reef and its worked well.
i run carbon and gfo 24/7 but dont relate them to nitrates in anyway,

[68shelby]

Yes I have a 45 gallon sump that will have a refugium in it as soon as I can get a light wired in. Right now the sump is basically 5-10lbs live rock rubble (inlet) under and over to the skimmer chamber then over to the refugium bed (currently about 4-5" of sand/gravel and then over into the return pump chamber.
And yes I have virtually 0 algae in the tank. even the back wall that I would leave for the tangs is bare other than pink and purple coraline. I wish I had some algae for the tangs.
Water flow is 2000 gph by the main pump,(probably somewhat reduced by the fact its in the basement) and I have 2 power heads one on each side of aquarium. 100g corner round.
Water I buy at sobeys. I have tested it prior to water changes and it tested fine. I am starting to think it is the mysis shrimp I have regularly fed.

[i have crabs]

how much rock in the tank its self?, i would invest in a ro/di unit so you can control your own water i woulnd trust buying water, not to mension the cost.
growing alge in a fuge will probably be enough to get the nitrates down from even the 20ppm mark but sound to me like there isnt enough filtering going on now

[alamo]

Are you seeing any signs of distress from your fish or corals?

[68shelby]

So got home tonight tested my nitates (hagen test kit) reads 20pm or slightly higher, disgusted I get water sample and go to LFS. They test with Elos aqua test kit Nitrates 5ppm, problem solved
Thanks to all you for your suggestions and I will still follow through on some recommendations and,
Thank you Josh @ MARINE AQUARIA

[Myka]

If you're spending $250/month on water changes, why not save yourself a few bucks in the long run and buy an RO/DI unit? You should be able to find one for under $200. Saves a lot of packing water around, plus you know what you're putting in your tank. Try testing the Sobey's water for nitrates (most nitrate kits will do both freshwater and saltwater). Also mix up some fresh saltwater (let it mix for 24 hours), and test nitrates in there.

LOL I just read your last reply as I'm typing the Quick Reply box...that's great you have your problem solved! When I'm at my wits end like that I double check test kits.