ok iam making a sump/wetdry togeather iam useing a 1 1/2 inch hole in the middle of my 125 for the over flow ! now i need to know how strong my return pump shold be with that size hole with water going down in to a 55 gallon sump some one told me 1800 gph ??? iam thinking this might be too fast for my space were i wont to put my pump can any one help on this ??

Hey there I am sure I can answer you question.The 1 1/2'' overflow will drain about 900gph.You can put basicly any size pump for your return.If you put a really big pump on your return like say more than your overflow can handle your tank could overflow ontt the ground! I have a 125g with four 1'' overflows they could drain about 2,400gph.My return pump is a magdrive 700gph.You can put a big pump on it but you will have to cotrol it with a ball valve regulator of some sort but it will likely from experience shorten the life of your pump.Also you have to keep in mind that pumps lose pressure the higher the water travels vertically.A pump that is rated 1,000gph will only be pushing about 700gph at 4 feet.If I was in your shoes I would get a magdrive 700 or 900 they cost like $80.00 but they work forever.Plus the more water you have going through that overflow the noiser it will be and I'm talking hoover dam loud.And you probably don't want to strain the overflow with alot of water because it will be easier flood if it gets clogged up.I pretty much went through all this stuff by trail and error over the past 17 yrs in the hobby and hope I was of some help.