If it is indeed Ich, then you have two choices. Keep fish stress-free and maintain pristine water conditions...basically hope they are all strong enough to fight it off. The Ich will still have the fish as a host, so it can come back.
Second option is to QT your fish, treat with copper or Hyposalinity and then leave your DT fallow for six weeks. Your QT fish should be cured and they go back into a clean, Ich-free tank. It stresses the fish, but the end result is worth it, IMO
Raising temp really does nothing (that works more with FW
fish). Cleaner shrimp or wrasses don't do anything. Freshwater dips can help, but are not a cure, as they will likely not get it all. Feeding garlic supplements is supposed to help the immune system, so that can't hurt, but again its not a cure.