When this happens on my screen I take it out straight away and use a shower to hose it off (try and do it into a bucket and throw it on your plants - good fertilizer, but it can block up your sink if you let it go down the plug!).Originally Posted by gasha
Just hose it off now, use your fingers gently if it doesn't all come off with the shower. Then rinse it once more when you're done, shake it out and put it back in.
Cyano has a habit of covering all the other algaes and smothering them, so best to get it off ASAP.
If it comes back, clean it again, but give it 2-3 days between cleaning.