Help me understand flow parameters

[masonmiles99]

I just got my first coral, a mushroom. I understand that they want low flow and low light so i put it on the sandbed in a corner.

Can someone tell me how i can tell vosuall or with my hand what high, medium, and low flow look like? The sand gets moved around a little bit on the bottom. I have two pretty powerful powerheads pointed more towards the upper 1/3 of the tank

 

[mcarroll]

The sand gets moved around a little bit on the bottom.

This is usually what I look for. Flow has to be able to keep food and detritus in the water for corals. IME, if it can't tumble small sand grains, it's not going to do it's main job very well either.