overflow?

im going to do an overflow like this on both my 40 breeders. both tanks will use the same 55 gallon sump. what size plumbing should i have going to the sump?

Make an overflow box - YouTube

 

First , determine the flow rate you wish to run for each tank and then use this chart to determine the appropriate pipe size based on a gravity driven (low pressure) flow. For example, using a 1" drain pipe will allow a max gravity fed flow of 960gph (this should be sufficient for a 40br with plenty of headroom to spare). Personally, I use a single 1" drain on my 34gal @ 200gph and two 1.5" drains on 125gal @ 1400gph.

 

i have no idea how much flow i want. i think thats the problem lol

 

ok i think im going to use 3/4" pipe.

 

Personally, I'd go with 1" if I were you. I wouldn't want to run the chance of clogging due to critters getting in the plumbing.

 

how will they get in the plumbing? it a hole in the bottem of a hob filter.