how much are you feedign and how often? red slime thrives on dissolved organics in the water, and phosphate. what are your water params? you can definately use the chemi-clean. ive had great success with it, however it shoudl only be used as a prophylactic. to completely eradicate teh problem, you have tot attack the source. this could be excess organics (food), nitrates (food, waste), poor circulation (add powerheads), or any combination of all three.
good luck and let us know what your water params areat!
jon