Originally Posted by craig_will2513
no i mix the new water in a tub and test it everything reads 0 i test my tank it reads about 40 on nitrate. so i do the water change leave it a while and test again and it is still the same so i know its not the test as the fresh water reads0
This doesn't make sense. How big of a water change are you doing? If you do a 50% water change in your tank- your nitrates should be cut in half. I can only think of three things that could be going wrong. You are not shaking the test long enough (one minute before dropping and 30sec to one minute after test for API products), you are waiting too long to read your test results (max five minutes for API test), or you are letting your saltwater sit too long before doing your water change (still saltwater in a bucket can cause nitrates to spike- don't know how but it happens).
Also, how long are you waiting before you retest??? A day? If so, do you rinse your frozen food off in RO
water? The excess can cause nitrates.