If just several spots have appeared, then I agree with the feeding of vitamin enriched foods and keep up the water changes. If a full infestation is in effect, your best bet is to painstakingly catch all the fish out and qt them. This is where hyposalinity comes in; otherwise, you will have to take notice of the parasites cycle. Since they have a drop-off period, you would have to vacuum the sand during that stage in hopes of providing some relief to your fish. Meanwhile, keeping them well fed with plenty of vitamins in order to keep their immunity levels up. It wouldn't hurt to raise the temp (80-82), which will advance the cycle stages.
