DIY bulkheads and plumbing

R

Ross110

will two 1/2" bulkhead have enough flow rate for a return on a 100g tank?
I am thinking i don't need two 1" drains on the back of the tank, so will 2 1/2" be enough? (1/2" =150gph so x2 would be 300gph at max siphon)
Before I start ordering parts, i want to make sure I am safe.


Is there any good DYI plumbing thread that anyone can point me to?
I have not drilled for plumbing before and I am not 100% sure on flow rates and what not...
 
You need about 5 times the tank volume in flow through the sump/fug. I would definitely go larger than 1/2 inch. 3/4 inch would work, better safe on the overflows. They have been known to get clogged(snails), why we generally use two.
 
For a 100g tank, I would still use two 1" drains. Think of it this way, the larger the hole, the quieter the flow down the drainline with zero risk of overflowing the display.

A 1/2" hole's surface area is very small compared to a 1" hole.

1/2" = .39"
1" = .79"
1.5" = 1.77"

A single 1" drain will handled 300gph very quietly, but can be maxed out around 500 to 600gph (in an internal overflow that has been installed in a tank with holes drilled in the base of the tank). Two 1" holes would serve you better, even if you only drain 250gph each.
 
Marc would those flow rates be the same for drilling on the back or just the bottom? I have a 100 gal with a tempered bottom but not the sides of the tank and was thinking of a 1" in the lower corners of the back of the tank and pushing water back up with a Mag 18 for my return pump.
 
WIth the drain closer to the bottom of the tank, you have more pressure pushing downward. Getting 500 to 600gph through a 1" bulkhead is feasible, but remember that all the plumbing thereafter can further restrict that flow.

Regardless, you don't need a Mag 18 for a 100g tank. A Mag 9.5 is more than enough, using 1.5" plumbing back up to the tank. You will save on electricity, add less heat to the water, and reduce the likeliness of microbubbles in the display.
 
i have 1/2" drain and 1/2" return, and I dont like it.

On a 55 gal main tank, with like a 20 gal refugium, and a $60 lowes pond pump.

I have to throttle the pump way back, 1/2" does not drain fast enough to suit me so I have to restrict the pump flow to accomodate the slow drain.

somewhere (maybe marc) someone said make your drain 2x the return.
 
For a 55g tank, a single 1" drain should suffice.

For a 75g - 90g, two 1" drains should be good.

For a 120g - 180g, I'd prefer a single 1.5" drain.

For a 200g - 300g, two 1.5" drains.

The return plumbing should never exceed what the tank can drain; the flow through the sump should be 3x to 5x the volume of the display tank. Specific plumbing varies in size, but if you are using Mag pumps, double their thread size for the return plumbing to get their advertised flow (and avoid heat issues from the pump).
 
That's keeping head pressure in mind. The difference between the Mag 9.5 and the Mag 18 is 800gph vs 1375gph (at 4' vertical rise). Again, the sump itself must be considered as well as the bulkhead hole size. Can the sump handle 1375gph shooting through it and not be the source of microbubbles? At 800gph, it should be fine, in most cases anyway.
 
Agreed.
Just think it's better to supply data as to why a suggestion is made in place of just the suggestion itself. You data is based on an assumption of 4 foot and what if his tank has a head pressure of 6+ feet like mine?
A 9.5 would work but so would a 12 possibly.

Just trying to provide usable data to the question and your answer.
 
Agreed. General rules work, but since we don't have specifics like the size of the sump, any suggestions we offer are groundless.
 
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