75 gallon build question

[Brownbear88]

1. I am getting ready to get the sump pump and begin this build but had some questions, first are 3/4 bulkheads ok? It has a overflow box with 2 3/4 bulkheads. Also how much flow do I need? And how strong should my return pump be? I have a 29 gallon sump. I will also have 2 500 gph power heads. Any information would be helpful because I am new to the sump set up and just need information on what to buy. Thanks

[StevenSeas]

Are the 2 3/4 in bulkheads both drains, returns, or one drain one return? And if they are one of each are you sure they are both for 3/4 in bulkheads, and one isnt for a 1" bulkhead?

Before you figure out how much flow your pump can return to your tank you need to figure out how much flow it can drain. A standard 1" drain can drain up to 600gph. HOWEVER if it is a 3/4" drain it can only drain at a safe rate just around 330-340gph.

So depending on how big your drain is or if both your bulkheads are for drains then you figure out what your head pressure will be (how high will the pump pump, and how many 45 and 90 degree angles. for every 180 degrees worth of angles add 1 foot to the head pressure. So if your tank is 5' above the sump with 2x 90 degree angles figure your head pressure to be 6'. Then find a pump that can do the gph that you need and at the head pressure. I would go one size up and put a ball valve on the output side just to be sure you can have full adjustment.

[Brownbear88]

ok so i have some pictures

1.jpg2.jpg3.jpg4.jpg5.jpg

so i have no idea if they are both drains or returns/drains, i went to reefs2u and paul had told me they were 3/4" and showed me a 1" bulkhead, wouldn't fit and really don't want to drill unless absolutely necessary. i know i need new ones see as the pvc was cut off for some reason, and the ball valve idea is awesome thanks. can you tell by the pictures what i have?

[StevenSeas]

Looks like it are designed to be both drains and have the return come up and over the back of the tank. In which case the max flow you could run after head pressure would be roughly 675 gph

[Brownbear88]

So then what would I need for a return? As in what piece of hardware do I need?

[Brownbear88]

Nvm think I've figured it out, you guys by chance sell them?

[StevenSeas]

Ya we sell them. Or you could hard plumb it with pvc and then have a bushing of either 1/2 or 3/4 inch and then get a loc line adapter and then use some loc line. We also have returns that hang over the edge and attach to flexible hosing.