[saltyair]

Originally Posted by mexxedm

I kept the rock wet with the existing water.
I used the old sand. Errr... is this the problem?
What is gfo?
What is gha?
What is WC?
==> Sorry, I am kind dumb
I do change water every week.

WC is water change
gha- green hair algae
gfo -Granular Ferric Oxyde Phosphate (removes phosphates from the water)

Yes your old sand would be a major factor. Have u tested NO3?

if you can remove it and rinse it or replace it it will help big time. the old sand probably had a big die off and had ammonia and nitrite the bacteria was working on.