Nitrite and nitrates

Question
I have a high level of nitrites and nitrates in my 180 gallon aquarium. I removed all my fish and removed all the water 3 times and I can,t get the levels to drop. My fish have not been in the tank for two weeks.

Answer
Hi Damon,
Is this a newly set up tank?  It sounds like your tank is halfway into cycling and almost done.  What is the ammonia level and about the nitrite and nitrate, how high is "high"?  What is good about your tank is you have nitrate readings.  Nitrate can only occur after ammonia breaks down into nitrite and after nitrite is broken down into nitrate.  It means you have sucessfully grown the 2 sets of beneficial bacteria needed.  All you need to do now is to continue doing 15%-20% water changes every 3-4 days until it is fully cycled.

However it doesnt make sense to me if you removed all of the water, and still have high level of nitrates.  Lets say Nitrates are at 60ppm, doing a 50% water change should instantly drop nitrates down to 30ppm.  Now with your tank, you stated you removed all of the water, and it is still high.  Perhaps your tap water is high in nitrates as there are some areas of the world with nitrates straight out of tap water.  Or if you are using test strips which is extremely inaccurate.  Liquid test kits provide a much better and accurate reading.  Another possibility I can think of is if you are using liquid testing, then the liquid might be outdated.
-Matt-