My saltwater tank has ick.(?)?

My 10g SW tank got ick… i think. My ocellaris clownfish and my mandarin goby got covered in a thin white film. My 6 line wrasse got a white bump on its nose. I had them for 6 months (I also have a cleaner shrimp, snails, crabs, hermits, lps, sps, and soft corals) A day after I noticed the ‘ick’, all the fish died, the rest of the stuff in the tank were alive. I let my tank sit at 78*F for 6 weeks and then I got an algae blenny (for hair algae), thinking the ick passed from my tank. 2 weeks later, my shrimp started to chase it around. The following day, the white film on it appeared and so I quickly pulld it out, put it into a quarintine tank with ick removal (copper), but it died. How do i get the ick out of the tank and know for sure it is gone without removing the coral and inverts?

Also, how do you get rid of hair algae. The blenny didn’t eat it, lettuce nudibrancs, hermits, and astreas didn’t eat it. I’ve also tried siliate/phosphate removers. (I use well water, but it has negligable amounts of minerals. It is a little high in iron, but it hasn’t been a factor for a year (since i started it.))