Check a post earlier this year about API test kits and the problem i had the link is below, this will substantiate what snowboss is saying. In short my test kits where saying everything was fine but it wasn't.
http://www.ratemyfishtank.com/phpbb/viewtopic/1591

My seaclone works great I did the modifications to it, and it removed crap like a MOFO. You have to shorten the collection cup tube, intermediate tube, and add a gang valve to the airline. I finally got my nitrates down to zero critters are loving it. The API test kit works fine. Going to start moding my PS4 here pretty soon adding the first devider wall tommarow. Getting two baseball sized clumps of Chaetomorpha algae soon so the fuge is in the works.