PVC reducing/head pressure

[rnelson]

For my skimmer I have a 1" bulkhead out of my sump. It immediately chokes down to a 3/4", does a 90⁰, runs about 1', does a gradual 90⁰ with 2 45⁰ elbows, then goes into a Panworld 250PS (45' head, 1900 gph). It makes a 4' run thru flex tubing into an ETSS 1800XR which is a 4 tower downdraft skimmer rated at 800gal. ETSS recommends at least an Iwaki 100RT which is about the same as my Panworld. The problem is that I am having to raise the water level in the skimmer too high to get foam into the collection cup. The water level is about 3" above the bottom box.

My question is this.......if I replaced the 3/4" run from sump to Panworld with 1" and took out the gradual 90⁰ (leaving just 1 90⁰ elbow), would that help that much? I'm just not sure if the 3/4" run is the problem or elsewhere.....it would be a hassle to replace and I want to make sure it would be worth it.

Thanks

 

[billdogg]

I would try to match the input side of your pump. If it is already 3/4", then it probably does not make a whole lot of difference, although fewer bends would be nice. If it is 1", then you really do need to upsize your plumbing (and straighten it as much as possible). Restricting the inflow can cause cavitation, and will certainly make the pump work harder than it needs to.

 

[James77]

The less bends and the wider the pipe, the better. I use an external return....I used to have it come out of the 1" bulkhead directly into a 90 elbow, then into a reducer then some barbs for silence. I was getting cavitation due to the flow being restricted on the inlet as well as turbulence.
I just re-did it all. I put the pump elsewhere. I still have the 1" bulkhead, but to make a full corner, I immediately jumped to 1.5" pipe with 2 long sweep 90* elbows, then reduced it to the pumps intake size right at the pump. All problems solved.

 

[sjm817]

I wouldn't use anything less than 1" with that pump. Bigger if you can. Maybe use a run of Spa Flex.

 

[rnelson]

billdogg, the input side of the Panworld is 1".....the Panworld recently replaced a pump that DID have 3/4", thus the reason for the 3/4" reduction.

So you guys think the problem would be solved going 1"? Or 1 1/2" and reduce right before the pump?

 

[rnelson]

I just measured the bulkhead, measuring on the threaded outside.....it is 1 1/2"......the PVC coming out is actually either glued or threaded on the INSIDE of the bulkhead using a reducer down to 3/4"....so, I assume I need to replace it with a 1 1/2" standard bulkhead? I guess I could just cut off the PVC and use a coupling with inside threading on the outside of the bulkhead......that might be kinda cheesy though.

 

[sjm817]

You always use the inside of the bulkhead. The outside threads are only for the nut to mount the bulkhead. A 1" PVC bulkhead is 1.75" OD. That looks like an acrylic sump. You should be able to carefully drill the sump for a larger bulkhead.

 

[rnelson]

sjm817, that's true.....haven't fitted a bulkhead in awhile and forgot that....what if I cut the PVC a little past the elbow, then go back to 1" or 1 1/2" straight down to the pump, then reduce back to 1" right at the pump?

 

[sjm817]

The right way to do it would be to increase the bulkhead size, but I get it. That is some work. How about getting a new 3/4" bulkhead, and increasing the size to 1" immediately after the bulkhead? That 3/4" 90 is not doing you any favors. Maybe a double 45 1" setup to smooth it out.

Are you sure that is a 3/4" bulkhead? It looks like 1" with a reducer to 3/4".

 

[rnelson]

Yes, I believe it is a 1" bulkhead with a 3/4" PVC reducer

It looks like the reducer is actually glued into the bulkhead

I could unscrew the elbow out of the reducer though.....

 

[James77]

I don't have a picture of my old setup, but it was similar to yours, just a bit closer to the tank.
I would bring 1.25 or 1.5" PVC right to the pump, and even use a union of the same size....then put a reducing bushing directly on the pump inlet.

Here is mine now....

 

[James77]

Ignore the 2 part crust.......it helps when the tube is in the sump

That is a 1" bulkhead, the pipe curve is 1.5", the true union is 1", as is the vinyl tubing. The velocity pump has a 3/4" inlet, it reduces to that right at the pump. The PVC hanger is there to secure the pipe, so if I bump it or the pump gets pushed by accident, it will prevent stresiing the BH hole and cracking the tank. Not that that has happened before.......

 

[rnelson]

Would I be OK to unscrew the 90 out of the reducer and go from there? Otherwise, since the reducer is glued in, I will have to replace the bulkhead also.

 

[James77]

It would work and be better than what you have now going that way....but if you are going through all the effort anyways, I would just use a large a bulkhead as possible. It would avoid that squeeze right at the start and can only help.

 

[sjm817]

Its not hard or expensive to replace the bulkhead with a new one. If you are going through the trouble of redoing the plumbing, get rid of that 3/4" bottleneck.

 

[rnelson]

I'll replace the bulkhead then....thanks for your help!

 

[rnelson]

The new plumbing....

Put in a new 1" bulkhead, came out with a 1" to 1 1/4", then reduced back to 1" before the pump.


Turned it on about 30 minutes ago......skimming like a madman!!!!

Thanks a lot for everyone's input!