[Floyd R Turbo]

Your tank could be going through a stage of transition (chemistry adjusting to the algae scrubber) and depending on the system, that can take a while (months) before you start to shift over to thicker greener GHA.

I would rinse the screen under room temperature tap water while rubbing, you want to dislodge any loosely attached growth. Think of it as survival of the fittest - you get rid of the algae that isn't strong in order to make way for the growth that is. Also you want to rinse away any detritus that may be built up on the screen, in the holes, or built up inside the screen panel in your case. So always rinse under running water (that pretty much goes for any scrubber screen).

You're doing the right think by clearing out the slime, just bump up your efforts slightly by rubbing + rinsing.

As far as the hours go, I don't know that going from 20 to 24 will make a huge difference, but as long as you are getting decent growth and no dead spots (from photosaturation) you should be able to run as long of hours as you want.