I used to have a 55 gallon reef tank that experienced a problem with dinoflagellates. The thick slimy mucus was all over my tank, mainly located in the prefilter box and in the wet/dry filter, where gas exchange occurs. The mucus would clog up my filters in my wet/dry in as little as 24 hours, repeatedly, even after replacing with new sponges. It was a nightmare, that's when I decided to just give the hobby up. I don't know how I got it? Now, i'm back but with a smaller tank 18 gallon. It's been up and running for 3 months now. The weird thing is that today I've noticed some long stringy substance clinging from my hang on filter into my tank. I hope it's green hair aglae. It's about 2 inches in length. I only use distalled water, it's about a dollar a gallon but I just don't want to go through that problem again.