Sorry I am at work and can not go on youtube :S
If you check my pics in my profile you can see how I have my PHs aimed.
I have two on the back wall on a slight angle aiming towards the return pump. The reason for this is because the return pump is rather powerfull plus the PH i have on that side of the tank facing length wise is modified and is like a 1600 gph
. Then on the opposite side of the tank facing length wise I have two, one aiming behind my LR
and one counter acting the 1600, which is a 1400. All depends how you aim them and if they are ricocheting off the glass or not. ...