I tried cleaning out the red slime manually and even had the lights out with the tank covered for 3 days and it always came back.
I just used this product a couple of weeks ago....worked like a charm. Try not to overdose as a little goes a long way.
After your water change, your protein skimmer may overflow with foam, but that stops in a day or two, especially if you're running carbon.
Some may argue that you're killing beneficial bacteria along with the red slime. Perhaps, but I think the removal of the slime is much more important. The good bacteria will regenerate.
The most important thing is figuring out how the slime got in there in the first place. If the cause is not corrected (i.e., excess nutrients, poor flow), the red slime will come back.