My tank got ich and velvet both. I am treating with Ich X Marine. This is day four and it had not cleared up. I did a 90 gallon water change prior to the treatment. The tank is a 180. It seems a little has cleared But the Blue Jaw Trigger does not appear to have improved. I contacted Hikari and was told Marine version is a little leas strong the standard Ich X due to corals. i wondered if I were to use the standard Ich X (nor marine) if it would kill corals or my crabs. I removed all of the carbon prior to the treatment.