Help with nitrates
 

I have been fighting high nitrates for far too long and don't know what do. My nitrates are usually between 10 and 15 when I test before a water change. I tried cooking half the rock first and then the second half. I have a shallow sand bed that cleaned up with a gravel vac. The tank is an all in one and I cleaned out the back chambers. Last week I did 25% water changes every other day and pushed the nitrates down to around 3 (tested on Sunday). Tonight they are 10 again.

I run filter floss that I change every other day. I have a skimmer that is rated for double the capacity of the tank. I don't normally run carbon but am right now. I have cheato in the tank and an turf scrubber in the back chamber (all attempts to lower nitrates). Nothing has worked.

The tank is a 28g nano cube with 30lbs live rock and a shallow sand bed.

I currently have 10lbs of rock in a cooking tub that came out of this tank and the nitrates in the tub are still climbing to 15 in a week, changing 100% of the water. They have been in there for 5 weeks now. Is it possible the nitrates are in the display tank are leaching from my rock?

Very much possible. Since you are saying that the water in the tub is also getting nitrate upto 15 in a week, so the rocks are the main criminal I presume :)

Have you considered introducing a nuisance algae problem to the tank?
Keeps my nitrates down...

How long have you had the tank running. How old is the rock

The tank is roughly 4 years old as is the rock. There are currently two types of nuisance algae in there.

Any ideas on what I can do? Throw in the towel?

I'm not sure if they make towels that absorb nitrates. Wait, do they? That would be totally awesome!!

Anyway, have you considered trying BioPellets in a reactor? If set up properly they can do a great job at reducing nitrates.

..seriously do they make nitrate absorbing towels?

Do you have any dead spots in the tank or detrus build ups in the tank

4 years could mean 4 years of detirius buildup in the rocks , you could try taking one rock out at a time and bleaching them then re add to the tank (slowly of course).Bleach eats all the organics in the rocks that could be causing your nitrates.

To give an alternate to toytech's post take a turkey baster or a big syringe to blast off a bit at a time to keep from continually restarting to tank by cleaning the rock heavily like that

+1 to Kien's suggestion for biopellets, or some other form of carbon dosing. I think they're making biopellet reactors small enough for a 28 gallon tank these days.

Fixing the problem will likely take a while though, as you need to both exhaust your bank of nitrogenous waste that your rocks are emitting (if that's what's happening), and get the nitrate reducing system up to a capacity that can handle the amount that's being produced. While that happens, you might end up with a cyano explosion (common when people start any form of carbon dosing), and the other algae will keep growing, so it might seem like it's getting worse before it gets better. The key will be to keep removing as much of the algae as possible, as routinely as possible until finally the nitrate reduction system starts to outcompete it and it stops growing back. Depending on your system, that could take a couple of months. If you just run the pellets or carbon dosing and don't actively remove the algae, you will wait a lot longer to see an improvement.