If you use polyquat, yes. It's a clarifier / coagulent, as well as an algaecide.

Regarding videos, most of the video formats have been used as virus packages, so if it's not on YouTube, I don't want direct links.

However, a picture would have done the trick; neither DE nor cartridge filters do well with live algae. You need to kill it before worrying about filter function.

Also, it looks like you are using DE in your cartridge filter; I recently found out that this can shorten cartridge life by damaging the polyester fibers. I recommend it to find filter leaks, but I probably need to set a policy of NOT recommending it to improve filtration on cartridge filters.