In my experience red slime is encouraged most by high fish load and /or
overfeeding and consequently a high nutrient content. The following would
decrease soluble nutrients:
1. Properly working skimmer
2. Routine gravel vacuuming
3. Get rid of all mechanical filtering except perhaps an overflow sponge
prefilter cleaned often. Mechanical filters are just nutrient factories unless
cleaned often (daily).
4. Use of Ozone raises ORP and "burns" out dissolved nutrients.
5. Don't overfeed.
6. Keep phosphates below 0.1ppm by water changes or phosphate sponges.
Tank cleaning is not a one time thing, you need to be diligent.
Initially, I had to kill my red algae with Maracyn which i consider an extreme
measure since it may also suppress ammonia eating bacteria so I dont know if
this is generally advisable. But my slime was out of control and it worked
well. I monitored ammonia levels just to make sure. Since then it hasn't come
back as long as I followed the above 6 steps.
