dskidmore
Aquarium Advice Addict
Something could still be producing nitrates. On your next water change, make sure to siphon up any debris on the bottom or on the rock, and rinse out your filter with the old water. You want to remove any gunk that may be breaking down into nitrates.
What brand of salt do you use? Have you tried testing your mixed salt water? Are you letting the new water mix overnight before use?
If your replacement water is reading 0, try mixing 1 part tank water with 9 parts new water, and taking another reading. The resulting read should be 1/10th of your tank parameter. Just a little trick for measuring above the top end of a test kit.
What brand of salt do you use? Have you tried testing your mixed salt water? Are you letting the new water mix overnight before use?
If your replacement water is reading 0, try mixing 1 part tank water with 9 parts new water, and taking another reading. The resulting read should be 1/10th of your tank parameter. Just a little trick for measuring above the top end of a test kit.