Originally Posted by
SantaMonica
Welcome.
Yes a HOG1 is a good choice for typical 20g setup. You can start scrubbers anytime; their growth (filtering) will just depend on how many nutrients are in the the water that need filtering. Typically, you will get some light brown or tan growth during a cycle, which is consuming the ammonia. (The light will need the shade cloth). Then when you add fish and start feeding, the growth will already be attached to the Green Grabber surface, and will darken and get thicker.