what is the GPH of a 1 inch hole for a side drilled overflow? I drilled my tank with a 1 and 1/4 bulkhead and it can not handle my 700 gph pump. it oveflows the tank so im adding another? I was just wondering if anyone knows the GPH of a hole about 1 inch in diameter?

I dont think that there is an exact way to answer what the GPH will be... but you are doing the right thing adding another hole. My large cuttle tank when i had it, had three 1" holes on the side panel and that was a 600 or 700gph pump

ok yea cuz i think i am gonan throttle my pump down too so it seems like it will work if the mesh coevring the holes doesnt slow the flow too much.

Okay, also watch for the octopus blocking the holes, thats another reason i had three in the first place... Spread them out :)

yea good call i will spead em out.