yellow growth on front of screen but green on back side ?

[Floyd R Turbo]

At this point I would take a shallow pan of saltwater (from your tank) and swish the screen in it with moderate vigor. This will cause any loosely attached algae to detach. Maybe rub the screen gently with your fingertips to loosen any other growth as well, but not much beyond that (no scraping yet). I see that the top edge of your screen looks pretty bare so you must be cleaning that or blocking the light, that looks good (no flow obstruction)

You might give the screen a very short exposure to tap water as well, but only a few seconds and then dip it back in your saltwater pan before returning to the tank

[Turtle Power]

hi Floyd thanks for the reply and advice , yes I clean the top of the screen every few days with a toothbrush, it seems to be getting going now

[SantaMonica]

Clean.

And get the burned stuff out of the holes too.