I am going to get a 75 gal. and make it my new reef tank. I was planning on having it drilled after I bought it. But now I am contemplating buying one that is predrilled from the bottom with a built in overflow. I understand that the overflow outlet is only 1 inch, which limits the amount of water turning over in my tank. Is this MUCH of a problem? Is there a way I could use this predrilled tank with overflow and add something to it to increase circulation? I hope you guys understand what I'm saying here, I'm new to this concept. Perhaps someone could explain the way this would work with a sump underneath and how the water flow rate relates to the size of the outlet. I just don't want to make a mistake. Thank you!

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A 1" overflow for a 75gal should be fine. I believe that some of the more knowledgeable members on this board stated that a 1" will accomodate up to 1000gph(someone correct me if I'm wrong). Additionally, you can always supplement w/ powerheads. But I know for a fact that you can get at least 10 times "turnover" w/ that design. HTH

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"Remember...Wherever you go...There you are."
Buckaroo Banzai, circa 1978

I have a 90 with a 1" O/F that will easily handle 800 CFM. I'm sure it could take more, but thats all my pump will push at the head I have. I think 1" is plenty for a tank that size.

-Perry

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Some call it evolution,
And others call it God.
Each In His Own Tongue (1908)
William Herbert Carruth 1859-1924

You will have no problem using the overflow kit that comes with your tank. Ensure that your pump has the guts to create the type of movement you are looking for. If you go with a submersible pump I would recomend a mag drive model 7 and a powerhead on the other end if you feel you are not getting the movement you need.

i have a 55 and im getting the flow i need at about 700 gph.
but i have a hang on overflow so i get alot of restrictions.
im sure a 1 inch is fine...if not see if theres room for another 1 inch hole or even a 3/4 hole??????????

Imagine how fast a 75 gal tank would drain if it had a 1" hole in the bottom. Pretty fast. A 1" hole is AAAALLLLLLLL good for that size tank.