PVC reducer restrict flow too much?

[Niterunner77]

Hello to all! Here is my concern. I’m currently planning to have a 180G Custom Aquariums Tank built and paired with a current sump that I own. The sump has (4) 1” bulkheads for draining. The tank has 1.5” bulkheads and drain pipes. Will I restrict my flow too much by adding a reducer fitting to make them fit together from 1.5” - 1”? The tank has a max flow of 2400G per hour with 1.5” fittings. Thanks in advance!

 

[Reefrodeo]

Just to be clear -
1) you're talking about the drainage from the tank overflow box to the sump(gravity) not the pressure return from the pump to the tank.
2) this is a conventional overflow box(s) with 1.5" bulkheads in the bottom of the tank.

If so, there is no problem reducing the pipe size to 1" below the bulkheads. The limiting factor on a gravity drain is the inlet size, not usually downstream pipe size(within limits). To clarify, the amount of water that will enter a 1.5" inlet with no head pressure is much lower than the friction loss of the reduction to 1" pipe with up to 2' of head pressure(below your 24" tank).

 

[Niterunner77]

Just to be clear -
1) you're talking about the drainage from the tank overflow box to the sump(gravity) not the pressure return from the pump to the tank.
2) this is a conventional overflow box(s) with 1.5" bulkheads in the bottom of the tank.

If so, there is no problem reducing the pipe size to 1" below the bulkheads. The limiting factor on a gravity drain is the inlet size, not usually downstream pipe size(within limits). To clarify, the amount of water that will enter a 1.5" inlet with no head pressure is much lower than the friction loss of the reduction to 1" pipe with up to 2' of head pressure(below your 24" tank).

1. Yes the drainage from overflow box to sump.
2. This is a external overflow box similar to a ghost overflow at the top of the tank with 1.5” bulkheads

 

[Niterunner77]

This is the exact overflow box that will be centered at the top of the tank so you can see what exactly it is.

 

[Reefrodeo]

With an external box, it's important that you install the reducer as low as feasible, so the condition I explained above is still valid, and the 1" reducer/pipe is not limiting flow.

 

[ca1ore]

For the drains configured as siphons, the reducer will be fine - chance are you'll be closing the gate valves below that anyhow. I would personally find a way to not use reducers on the open channels, either by just removing the 1" bulkheads from the sump or over drilling a 1 1/2" bulkhead.