Not sure what effect the soft water will have. To increse your odds I would use RO
water, cut back on feedings, do 10-15% PWC
every three-four days and run a PO4
sponge. Keep in mind if you are using Chemi-Clean you will need to turn off your skimmer and remove any chemical filtration (GAC
sponge) during the treatment. I would do things in this order...First, syphon out all of the cyno you can see and do a 20-30% PWC
water. Next, add the chemi-clean and turn off skimmer/remove chemical filtration. Wait 48hrs. Do another 20% PWC
free water and begin skimming and chemical filtration again. Smaller water changes every few days until the end of the battle. Good luck.