Throw one of these in your tank and place it near the bottom. It comes with a white pleated 15-micron filter. Theronts(free swimming ich) are too big to pass through this filter. This should cut down on free swimming theronts. You don't need to mess with messy diatomaceous earth, though this filter will run DE with that same pleated cartridge if you wish. DE would be good to capture velvet.
https://www.amazon.com/Marineland-P...&qid=1531949644&sr=8-4&keywords=magnum+filter
Thanks for the tip. Will this remove the Ich attack from my system?