Please have a look at these photos...

[Brew12]

Wow! Vacuuming and churning the sand bed made a huge difference. Cyano is all but gone.

Apparently, whatever the cyano was feeding on was locked up in the substrate... which would explain why I saw it on the substrate only.

Thank you for the help!
Dom

Fantastic! Glad it works for you!

 

[Dom]

Fantastic! Glad it works for you!

Yes.

I actually received my order of Chemiclean the other day. But I have to say that I am reluctant to use it. I don't like how it pulls oxygen out of the water (which is why they want a supplement via air stone).

It's ok... I'll just add it to the supply of stuff I have purchased over the years and never used. LOL

Thank you again.