Hi, I use a 20 Gal covered but not sealed Rubbermaid to mix and store my salt water for use with an auto water change system. I use Tropic Marin Reef Pro with 0 TDS RODI and heat/circulate it. I never let the bin run dry so as to keep things rolling with my AWC. Over time, I get this black stuff that looks almost like mold covering the surfaces inside the bin except where the power head is blowing. It is even floating on the water surface and collecting on the wall at the water line.
Any ideas what this may be?
Safe to ignore?
Any ideas what this may be?
Safe to ignore?