I'm setting up a 29g reef aquarium. I plan on foregoing a protein skimmer and refugium and going for a ATS. Unless someone can point me into a cheap and effective DIY HOB I'll probably use a small 5g tank to make a in sump on under my aquarium. I plan on drilling holes for the in/out flow, with the in flow feeding the ATS without a need for a second pump. I also plan of having a med stocked tank about 4 nano sized fish total. So I'm going to assume for the moment being I'll be 1/2 a cube a day feeding. So the plan I have is to make a 3x4 screen with lighting on one side. This way if I need to I can always add a asexind light and play with exposure times. I also know the targeted flow is 35gph per sq inch of screen. So really my question is how big of a overflow hole is really needed to achieve this? Can I just use a ball valve to get where I need it, or will the slots I cut only allow x amount of water to pass at any time? Also if someone can recommend a cheap return pump that'll be helpful.