sump and AS plans, flow Q

[treesprite]

I need to use less horizontal space and need to make use of all the little tanks I have had sitting around full of tank junk instead of water, plus want to make an AS out of a 16H so it will be contained. So instead of using my 40B sump/fuge combo, I'm going to try to go vertical.

 

I have a 20L and 2 x 16H tanks (one is a actually a bow). I drilled 2 holes halfway down the 20L, that have 1/2" bulkheads (I was thinking 3/4" ones would be too much). The plan is to have one go down to a 16H to be used as an algae scrubber since it seems perfect to use for that purpose, and the other 16H for other stuff.

 

I am now wondering if a single 1/2" bh will be enough flow for the AS. I am only going to be able to fit the width of one sheet of plastic in the 16H ( could use both containers for AS if one isn't enough). My question for you is, will the 1/2"  be enough flow, or will I have to drill another hole?