Have you ever considered dosing vinegar ? I struggled with keeping nitrates and phosphates low for years. I have used bio pellets in the past they work but I always ran into issues with clumping or a clogged pump slowing down flow to the reactor. If you don't already have dosser you can pick up a jebao dosing pump for under $100 they work great and Vinegar is cheap. I have been dosing vinegar for about six month now and my nitrates and phosphates are mostly undetectable. I don't even run gfo anymore .
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