[DrHank]

I agree with Scott. What was happening was that your bio balls were so full of grunge that the wet/dry wasn't working properly. When you cleaned it up it started to work like mad. The result was that it took any residual ammonia and nitrite and rapidly converted it to nitrate. That pushed your nitrate off the scale. Congratulations, your wet/dry works perfectly. That level of nitrates would kill almost all corals and many marine invertebrates. That is exactly why reef enthusiasts don't use wet/dry filters.