high nitrites, ph and alkalinity

Question
I have a 4 month old 10 gallon fresh water aquarium.  I have a power filter and air that pumps through the cave we purchased.  Our fish keep dying.  Right now I am testing with the all in one strips.  I have two black stiped tetras and a small catfish in the tank right now.  The readings come out as caution on the nitritres, nothing in the nitrates and high on PH and alkalinity. Yesterday I swapped out 50% of the water and tested the water before I put it in the tank and PH and alkalinity were in ideal ranges and no nitrites.  I put the water in the tank, tested it this morning and nothing has changed on any of our analysis.  How do I get the nitrites to zero and the PH to come down if its fine when I put it in.

Answer
Hi Maria,

The first thing I would do is tank 2 cups of tank water to your local pet store and have them test it for ammonia, nitrites, nitrates, pH and hardness.  This will give you a baseline on the water quality.

Nitrites are lowered by beneficial bacteria in the tank.  High nitrites typically means one of two things.  Either the tank is not fully cycled, or it's being overfed.

Here is a good article on the nitrogen cycle:  http://www.aquaria.info/index.php?name=News&file=article&sid=376

In the mean time I would do a 20% water change daily for the next 5 days to lower overall nitrites in the tank while the cycle completes.

Sean
Owner - FishGeeks.com