For the spray bars, just take the brush they give you and take out the bio wheel, let it float or something and just brush over the spray bars while the filters on and stuff. It's usually calcium build up or a piece of carbon thats in there. 
ewurm said:Is it better to use two small filters as opposed to one big one?
gomezladdams said:Thanks for reminding me I have to clean mine in the morning
The Hagen Aquaclear 110 is rated at 167-500gph and designed for use in a tank of 100g and below, It is a bit excessive in a 20g.
I used 2 plus a UGF made for a 55g tank in a 150 containing (8-9) 9"RBPs and the combo worked great