Chemi-clean is an oxidizer, which works by increasing the level of dissolved oxygen in the water, limiting photosynthesis and strengthening aerobic bacteria. When using it, it's very important to keep the water flow strong, and have plenty of air (via protein skimmer, air stone, etc) in the aquarium. It does limit the photosynthesis of zoxanthellae algae within corals, but normally not enough, or long enough, to cause any damage. The lack of photosynthsis and competition from aerobic bacteria, causes the cyanobacteria to die off.
Red Slime Remover is an antibiotic. It kills the bacteria, but also kills beneficial bacteria. If you're between a rock and hard place with cyanobacteria, I would choose chemi-clean over red slime remover. Phosphate levels of .25 ppm are most likely fueling the outbreak. You will want to add either a GFO reactor to your tank, or something to keep phosphates down. Instead of either chemi-clean or red slime remover, I would try Brightwell Aquatics Phosphate E -
Brightwell Aquatics - Phosphat-E, along with Pura Phosloc in either a HOB filter, or reactor.
PURA PhosLock GFO Phosphate Removal Media.
This will kill the cyanobacteria naturally, without the need for chemicals, and remove the phosphates, so it doesn't keep coming back.