Hey guys changed my GFO recently. I use Seachem phosnet in a Seachem bag with low flow as reccomemded. I have macroalgae and feed 1/2 cube a day and 1/3 algae sheet 3x a week. So my phosphate test always reads 0 (tried multiple test kits), however finally I've had cyano come back. Changed it and cyano went away. Phosphates still at 0. The GFO last 6 months and 3 weeks. That's amazing and far more than I expected. You guys have any similar experiences? Does anyone else also need to rely on things other than phosphate levels to decide when to remove GFO?