Nitrite levels

Question
We have a 72 gal bow front. It has been established for over one year now. YET we still have our Nitrite levels at 75 to 100. Water changes bring them down, yet soon they are back up. We know that it is overstocked (clown fish, 3 chromi's, yellow tang, copperbanded butterfly, & strawberry)
Getting rid of any of the fish is out of the question, our six year old would be crushed. My husband wants to buy the aquaripure denitrator. Is this a good idea?

Answer
Angela,
It sounds to me that your system has never fully cycled. I dont have any other readings for your water quality to be 100% sure but thats what it sounds like to me. Sometimes what happens in systems is the cycle nears finish and aquarists add fish. This creates mini cycles. The nitrifying bacteria havent had a chance to populate enough to keep up with the load on the system. Water changes aleviate the stress, but it can take a very long time during these mini cycles to create a large enough population to completely cycle and the tank to stabilize. Ive heard of and seen systems go for much longer than a year with this type of problem. Dont despair. One thing to look at as opposed to an expensive add on is the depth of your substrate and the amount of live rock in your tank. A tank that size, with those particular fish should have at least a pound of each per gallon. Your population really isnt that large for the size of the aquarium. I personally loaded a 55 gallon system with 2 2 foot long morays, a red volitan lion, a niger trigger, and 2 mandarin dragonettes for my office. I also have 70 pounds of live rock, and a 4 inch deep substrate(approx 55 lbs). I have heard mixed stories about the units you ask about. I generally have found, personally, the one I used clogged and ran poorly. It never lowered nitrites or nitrates. The unit itself has to cycle, and grow the bacterial population it needs before it can be used. In my opinion a waste of money and time. I would check with your local fish store for some quality live rock, and a bacterial additive, like Stress Zyme or Spirulina, to kick start the cycle and allow natural stability to occur. Water changes are the best way of allowing this to happen. You can also look at a variety of macro algae that can really enhance water quality and the beauty of a display tank. Dragons Tongue(halimenia), Chaetomorpha, Halimeda and Haliptilon are a few that are great contributors to high water quality and can be striking additions to any display at a very low cost to the aquarist. When cleaning and doing water changes make sure youre not siphoning the substrate too deeply or cleaning any filter media too thoroughly as this will also deplete the biological filters population. Take a look at the size of your water changes. Im a 50% guy myself with systems under 100 gallons. I do a 50% water change every 2 to 3 week on my 55's, 75 and 90 gallon tanks. Also feedings. Frequency? Quantity? Make sure there isnt extra food floating around to sit in nooks and crannys in your system. Hope this helps.

~Glenn