What's the best way to tackle this?

[James5214]

So I thought it was diatoms at first but then I finally got pure white light bright as can be and this is what I saw. What should I do to get rid of this? My fish are starting to yawn and breath more rapid since I read cyano when it decomposes takes all the O2 out of tank. Thanks guys

 

[blaxsun]

What are you running for wavemakers in your tank?

 

[James5214]

Some cheap hyyger and on the lowest setting it's a 20L and has a tidal hob filter as well but there is some dead spots