Siphon overflow design (pix)

[rob1116]

(Not for my tank)
Does this design make sense? I have no experience with siphon overflows... so let me know if this is okay. The red line on the top will be connected to a venturi line off a powerhead. Regardless of that, the baffles should maintain the siphon right?
Thanks again all!

 

[dreeves]

Very similar (scratch the whatever in the middle string looking thing) design to a couple of manufactured ones...

 

[beaslbob]

Originally posted by rob1116
(Not for my tank)
Does this design make sense? I have no experience with siphon overflows... so let me know if this is okay. The red line on the top will be connected to a venturi line off a powerhead. Regardless of that, the baffles should maintain the siphon right?
Thanks again all!

Just a few observations here based upon my limited experience and the comercial overflow I purchased. Mine uses a round u tube. When powered by a powerhead it did tend to accumulate air with the possibility of breaking syphon. With my new mag5 the flow through the tube is fast enough the bubles are just pushed on through. I fear a square overflow with low flow rates woud probably trap more air and more easily break syphon.
I could not get the air tube from the u tube to pump intake to suck the air out. I left the tap there with a valve to manually suck out the air to reestablish the syphon after cleaning.
The water level outside the tank must be lower then on the inside skimmer box for water to flow through the syphon. As you have it drawn no water will flow.
The baffel just to the left of the drain may not be necessary. Or at least as drawn it may be too high. Running the drain pipe higher will limit the overflow.
You may want to add some adjustment feature. My commercial has a nylon wing nut to allow moving the skimmer box up or down.
I presume you want to add some filtering material to prevent livestock from entering the sump/fuge.
Again these are just my first "gut feels" and I have no experience with that particular design.

 

[robchuck]

The design looks somewhat like the CPR brand overflow. I would be concerned about air bubbles building up in the squared off areas where the water goes over the tank's lip. Too many bubbles building up would cause the siphon to break.

 

[rob1116]

Bubbles will build up even when the line on top is constantly connected to a powerhead?
So a peice of U-pipe would be better?
beaslbob: Re: the last baffle. Ahhh... that's a great idea! And if I'm going to put a standpipe anyway... is there any harm in putting a durso in aswell?

 

[bigmac]

Originally posted by rob1116
So a peice of U-pipe would be better?

looks good, I used one for 10+ years with just a U-tube and it NEVER FAILED ONCE, no powerheads no air thingy ma-jigs on top of the U-tube....

 

[rob1116]

Really...
To me, it seems like it would be impossible to break the siphon as long as the baffles are sized correctly. If anything, I would think that adding the fitting to the top of the U would just increase the likelyhood of losing siphon... ie. from a leaky fitting/hose.
Next question: I'm putting a 1.5" bulkhead in this thing. (I have one already) I don't want to run a 1.5" U tube over the back... so could I use 2x1" tubes? Also, is it okay to just make the tubes out of PVC and a couple of 90° 's ? I can't see why not... just double checking.
Once again... thank you x1000!

 

[rob1116]

Last Q I swear!
How much does the height difference between the tank water level and the drain pipe? Namely, would it affect my flow much if the downpipe from the overflow box, (going to the sump) was only 1" lower than the tank level?

 

[toyatgrnd0]

there is no need for the baffle just extend your pipe up to where it sits about .25"- .5" depending on gph below your tank level and the syphon hose going to the powerhead is not necessary its just as easy to fill the pipe with water put your thumbs over both ends and stick it down into the overflow given that both sides are full and then release your thumbs and when your pump starts pumping water it will start syphoning

 

[rob1116]

Yeah... I think I got it now. How's this?
The bulkhead/drain pipe will be 1.5". I'll put two, 1" U-tubes. Is that okay?

 

[toyatgrnd0]

there you go thats pretty good i ive built quite a few and that will work great sometimes that make a little noise but only when there low on water

 

[rob1116]

Any reason i couldn't put a durso style standpipe in there to silence it?

 

[dreeves]

Having the drain pipe lower then the water level will help with the siphon...
Even a square tube will allow bubbles to pass through and not build up (despite what was inaccurately stated above) if the water pressure is high enough...which would be about the flow rate as the rated overflow...
And prior to messing with a durso standpipe...get the overflow up and running and see if it is needed...then if it is...try the standpipe silencer...

 

[rob1116]

Okay Thanks... I like the square acrylic 'pipe' design better anyway.
One more thing about flows.
The skimmer box will be 8" wide. The bulkhead is 1.5". (I know it's overkill, but I have one already, so) I plan on making the square 'pipe' section 1", and of course it runs the length of the inside of the skimmer box, (~7.5").
Any idea how many GPH this will give me? Any problems with these sizes?

 

[dreeves]

Can't answer this...I have a new overflow which is 8 inches wide...with a 1" U tube it is rated at 800gph...I have a 6 inch wide with a 1" U tube and it is rated at 300gph...so I do not really know to answer your questions..

 

[rob1116]

Ok thanks. Then mine should be able to handle 1000+Gph. Not that I'll be going that high, but it's nice to know.

 

[rob1116]

One last thing guys/gals!
I can't find proper acrylic cement anywhere! Can I just use aquarium safe silicone? Will it hold the weight of the rear box?

 

[fat_tony]

if you are only using silicone the answer is no. Never trust acrylic and just silicone you will end up with many puddles.

 

[rob1116]

Really? What am I supposed to do then? I've been looking for a Canadian supplier of 'Weld-on' (online or otherwise) for a long time with no success.
Anyone know of an online retailer that ships this stuff to Canada?

 

[rob1116]

Bump... for a Canadian retailer?