What are ways I can get this stuff gone because its still killing my coral.

Setup:
75g tank, 125g coaralife skimmer, ~20g sump with fuge', rio 3100 pump, 1 power head in tank. Soft corals are in the tank but a lot of the polyps have been killed because of the bacteria.

So far, I have been siphoning out any bacteria I can physically see. However, its even in the fuge right now and that is almost impossible to get it out. I added a phosphate pad, 2 bio chem bags, did a 40g water change and going to start doing 5-10g water changes every other day. I also bought a new light which should arrive next week. It was mentioned that the metal halide lights will change color spectrum and that cyanobacteria likes that. I have also decreased the amount of food fed to the fish. Also, have not fed the corals the liquid stuff I have (can't think of the name at this second).

So what else is there for me to do?

Thanks