DIY Weir Overflow Box

[Fishman0]

I think the reason for the second chamber is to ensure the siphon from the yellow u-tube never breaks. therefore the system never has to be primed unless the tank level reaches the inlet of the suction side

 

[gjohal]

I think the reason for the second chamber is to ensure the siphon from the yellow u-tube never breaks. therefore the system never has to be primed unless the tank level reaches the inlet of the suction side

So your saying if the water line in the tank is lower then the "T" portion of the overflow it will break the siphon correct?

 

[dmopar74]

I think the reason for the second chamber is to ensure the siphon from the yellow u-tube never breaks. therefore the system never has to be primed unless the tank level reaches the inlet of the suction side

this is incorrect, there is no need whatsoever for the second chamber as the first chamber will always be full up to the T no matter what, preventing siphon breakage unless tank was drained below siphon.

 

[john73738]

Here's a thread with some that I made for someone. There is a cut list of sorts and an explanation of the operation. It should give you some ideas to play with.

Chompers,

As i stated above I LOVE to over complicate things.

Would you please explain how you would cut this or does it matter??

I was thinking of using 2 on a 4' 75 gal tank. What pipe size would I use to achieve 700ish gph?

Or should I just use one.

Want to build the sump this weekend and this is my first attempt.

Thanks

 

[CHOMPERS]

Would you please explain how you would cut this or does it matter??

I would use a hacksaw, but it really doesn't matter. For big jobs, I use a chop saw or a ratcheting pipe cutter.

I was thinking of using 2 on a 4' 75 gal tank. What pipe size would I use to achieve 700ish gph?

The math will have to wait a while. I've met my math quota for next month already and I'm way behind in doing math for other members.

For now, use the sticky thread for finding pipe sizes (I think you already found it). Use the chart at the bottom for "horizontal gravitational flow". If you have problems, just let me know. However, I really am behind with helping others.

 

[john73738]

Thanks Chompers. will use your chart.

2 final quick ?s

can I use 2 or just stick with 1, and is there a specified length of the pipes like in the other design you have in that thread?

 

[fcamargo6thave]

i have seeen people do overflows from plastic milk bottles so pvc should be cool

 

[Sirspifalot]

2 pipes work but if I do recall one pipe of the same size of 2 combined pipes will have more flow because there is less surface contact and there for less friction. So for example one 2" pipe would handle more gph than would 2 1" pipes.

 

[F.F. Julio]

2 pipes work but if I do recall one pipe of the same size of 2 combined pipes will have more flow because there is less surface contact and there for less friction. So for example one 2" pipe would handle more gph than would 2 1" pipes.

you are exactly right this is called friction loss you will also lose more flow the longer the pipe is. Think of it like this, its different than using PVC but you should get the idea. A 50 foot section of 1.5 inch fire hose has a friction loss of about 13 psi per section, where as a 50 foot section of 3 inch fire hose has a friction loss of about 5 psi per section. I hope this helps.

 

[broken]

I might have to steal this idea but my only question is what do you use for a check valve to start the siphon?