Does phosphate "stain" the tank?
I made the mistake of dosing powder form pH down into my old tank and now no matter how many WC or phosphate removal pads i put into the filter, its still at a very high level.
I've taken a sample of my supposedly inert substance (Onyx Sand) into a bowl and put some tap water into it. Measures 0ppm of phosphate at first, after a few days its >20ppm.
Is my tank done? do i need to use my filter material / substrate to remove phosphate completely?