Treating Cyanobacteria in 8 Gallon Nano Tank

[chromakey]

Good Day:

I treated my tank for cyanobacteria with Chemi-clean about 6 or 7 months ago and it got rid of most of it but there was a layer of green and purple cyano in the sand layer against the glass. It didn't seem to do anything but the last couple of months I was getting a bit at where the sand meets the glass. I have been siphoning it out with my water changes. I am planning to treat again and wanted to see if it is recommended to expose the cyano against the glass.

Thanks,

Michael