So I’ve had this brownish coloured film starting to develop on my filter sock now daily. Before it would slowly build up but now it’s to the point where it clogs the mesh filter sock in less than 24 hours. My phosphates are at 0 and my nitrates are between 5-10. Does anyone know what this is and what is causing it? You can see it sprays off very easily in the sink with the nozzle sprayer. Thanks so much for your help.