I and a lot of other SW
tank owners do not use tap water because it has contaminants like chlorine, ammonia, nitrates, silicates etc.. All the things that can make a saltwater tank look and feel nasty. We use RO
water, which comes from an RO
unit(shocking, i know :p)
You can find some cheap units on ebay and it is completely worth buying one since it makes life SO much easier. Also, try to stay away from chemicals(the softener product) because chemicals can upset the balance of a saltwater tank easily if used even the slightest bit incorrectly.
About the clowns, i would say that they are just breaking the food down. My clowns used to suck in the food, spit it out, the suck it back in, and continue that until the food was a smaller size for them to eat. I would keep watching them, and if they begin to ignore the food completely, that would be a sign that something is wrong.