Overflow for 75 or 90g penninsula

[Roca]

I'm gathering supplies to build a 75 or 90 gal penninsula for my parents since they are adamant to have a tank after seeing mine. This works out because I get to build another tank and I get to basically have a third tank to acts as a grow out tank I see only every few months and be amazed at how much it has grown... hard to do when you look at a zoa everyday trying to find a new bud... hahah. This tank will mostly softies with the odd lps. Super easy to maintain with colorful coral is the goal.

The only real issue I'm having trouble planning out is what overflow to use. Almost certainly I am going to get a modular marine from eBay. The question just becomes either the 800gph (8") version or the 1200gph (12"). Both have three drains to be able to set up a bean animal which is a must. I plan to drill two 3/4 return lines at next to the overflow. The two questions I am struggling with are:

If the 800gph, are those 1/2 drains something to be concerned about? I anticipate only doing about a 4-5x turnover rate so maybe this is actually fine.

If the 1200, would I be having issues drilling two return holes since this leave me only 3" on each side? I don't want to have the return holes too far down so they would definitely end up being shy of 2" from the edges.

 

[diana a]

I have the Mod Marine 1600gph, but it is the smallest model that has (3) 1" drains. I had planned on a 75 or 90g tank. I am currently using it on the 40B with no problems. The next size down is 3/4" drains (1200gph) and I personally would not use that on 75 or a 90g. Modular Marine website is closed but I know if you email him, he will answer you. If the item is in stock he will ship it even though he is closed. He closes when he is in need of stock to make the overflow boxes. When I bought the overflow box it wasn't a question on turnover...that can be regulated by a gate valve and dc plump. I wanted the emergency pipes to have the ability to handle the drainage if the 1st and 2nd pipes got clogged