Bulkhead for intake and return sizes?

[Tobykourtney]

I'm starting a 20 gallon with 10 gallon sump and was trying to figure out what size bulkhead for intake and return is needed. I'm aiming for 300 gph flow. I'm thinking 1 inch bulkhead with .5 inch return. Does this sound right?

 

[cdonaldson]

On a drilled tank gravity feed on this with no other outside factors (air intake, head length, ect.) will yield in the neighborhood of 420 gph using sch 40 pvc.

 

[Tobykourtney]

Thanks
The sump is sitting directly behind the 20 gallon. When I'm done with the canopy the 10 will be hidden. Would this affect the flow of the intake negatively?

 

[cdonaldson]

Yea it will effect the flow rate. I guess I need a bit more information.

Are you using an over the tank siphon or are you going to drill through the tanks?

 

[Tobykourtney]

I'm going to drill it

 

[cdonaldson]

So your going to drill it at the top to set your water level. I would go with a 1.5" bulk head to a 1" PVC. This will give you basically zero restriction. So your GPH will then be set by your return pump. I would buy a pond pump with like a 350+ GPH rating and dial it down as needed. Since your head will only be at the most 12-14 inches (you can google a head calculator to see how much it will effect your GPH) it shouldn't effect your flow much. I could be overlooking something but this basic math seems correct.

 

[Tobykourtney]

Would the bulkhead return size matter?

 

[cdonaldson]

Since your pump determines the GPH flow I would just drill the return for whatever is most convenient for the pump that your using. The main thing to look at for your return is the turbulence that will be created by your return. So the larger diameter PVC you use the less turbulence that will be created when returning clean water into your DT. You need to make sure that your being able to push enough water out of your sump to prevent and overflow since the height of your sump is lower than the height of your DT. I would make the return the same size as your intake if possible so that your not creating a 90 MPH stream for your fishies to fight.

 

[cdonaldson]

Also, if you drill your return lower in the tank, it may help to stir up sediment that collect on the bottom and push it to your sump intake. You can also play with putting a dry fit 45 fitting inside the tank to redirect the flow of water.

 

[Tobykourtney]

I was going to make a hole 2 inches from the top on the right side for the intake and a hole 2 inches from the top on the right side for outflow. I'm thinking of making both holes 1 1/2 inch bulkheads