Nice Cheap DIY Overflow

locutus your design would work fine thought the elbow you mention isn't needed in the bottom of the larger pipe.

BWY I don't think that that design would work when the inside half of the overflow is that close to even with the outside half of the the overflow does not move much water(handle low GOH for plumbing size.

Second surface skimming is a BIG reason most people set up overflows and the point that you made about that setup sucking air would make it fairly risky.

But hey what do I know it would only be $15 to build that so you could test the design if you want.

 

I've added the link, Mac is awsome, Although i like being able to pick the parts in my pc, I'm using "Firefox", Its available for mac as well and has many more pleasant features. The elbow is pointles because the outside pipe becomes the elbow, aslo the outside pipe becomes a new container with its own water level set by the output.

the new diagram shows the water levels whith no flow, if the water level is at blue inside the weir its more likely to catch air inside the U above the tank, with enough air it fails. by moving the output higher you have less chance of this happening because the air has to be sucked down even further, that is why i would say you need more length, In purple i would place some filter wool inside a stocking, this will indefinately prevent any vortex from happening. when the water level reaches red its time to pull it out and give it a rinse through.

a vortex is created when water speeds up to enter the narrow pipe, as it is going into on centre it begins to curve, as the curve increases it starts to spin water inside the pipe, this centrefuge creates a negative presure in the centre wich begins to suck air in, if the speed or flow of water is sufficient then there will be enough force to suck air in, if the pipe's diameter is smaller, then the speed is increased, if the pipe is closer to the surface of the water then the space water is entering is smaller and so the speed increases as well.

http://psycotech.com/overflow3.jpg

 

Thanks for the input. Great idea on the overflow exit being higher BWY. Covey, I think you are right about the 2" outside pipe being too small, i'll make the diameter bigger to accommodate more flow to the inside pipe.

 

WOW impressed with all the the designs good job guys, im about to make one too. i need a plan, i have a 35g hex what size tube i should use and what size return pump. i just want to get those match my tank size. i want efficient flow thanks guys.

 

If your looking for efficient I would go with a small return pump and then run powerheads in the tank. It is far more efficient than a large return pump.

I would run like a mag5 and a 1" PVC overflow. I think that would be a good match.

 

i built one like covey's in the main part of the post and other than twice having to reglue the check valve after it got bumped and broke siphon all has gone great for me with it.

Though soon i'll feel confident in my ability to keep my tank that i might start looking into appearances a little and i might try the hidden pipe method. Essentially it seems to me to be an overflow thats just not attached to the inside of the tank like most are, neat idea i'm surprised someone hasnt mentioned it before. Would look sharp and still give the surface skimming.

My next project is going to be trying to put an automated water changer on my FW puffer tank. Has anyone ever ran into a post somewhere where an over flow like this was used on a once daily basis for a few minutes? I read over some on a mostly FW board but i was just wondering if anyone here would be as worried as i am that only running the overflow for four to five minutes would allow enough air to build up to break the siphon.

Most people i've ran into with auto changers used a solenoid on a standpipe in their sumps so they didnt have to worry about it. however i dont have space for a sump on my 75 right now or a spot to go through the floor in the present location to make that practical for me.

I was also wondering about my overflow to the refugium on my FOWLR, right now its about 1/2 and inch above the water line, would being under the surface of the water be horribly bad? I was using it for aeration but good god i'm loosing water faster than i can get to the store for RO refills. No leaks in the tank or odd salt creep anywhere its just around my refugium from the splashing of the water return.

Thanks a million for the input, back to pondering what to do with my 100 gallon tank....three choices, one expensive, one mid range price but eats a lot and one cheap and pretty but possibly boring....

Jason

 

Couple of Questions

Covey,

After reading the entire thread several times, I decided to attempt. I left the check valve off because I am not sure which way it goes. Could you elaborate on that?

Also, step by step on priming and getting the unit started would be awesome! For some reason I am having trouble here.

Thanks!

 

You put the check valve in there so you can suck air out of the high point in the elbow. So it has to be in there to create a siphon. If you where trying it with out the check valve it would not start.

How to start the Overflow:
1) Place on tank, let front side fill with water.
2) Take a cup and fill the outside bottom loop with water until it runs out of the output.
3) Draw air out of the siphon loop thru the check valve.
4) Start the return pump. Any time you totally empty out the overflow the first time you start it keep an eye on it as it flushes out the rest of the air bubbles.

After that it will be rock solid if built right. If in doubt test it in a 5G bucket and use a hose and make as many starts and stops as to want.

 

Guys, i'm going to go ahead and build one of these tonight.
I've been looking for an option for putting in a sump, other than putting all my livestock in temporary tanks and geting my tank drilled, this looks like ideal option.
I might put a Juwel filter box in the corner of my tank to conceal all the pipework. This would also allow the heater and some powerheads to be hidden away in a corner inside this unit as well.

Chris

 

well, i bought the parts, built the overflow, and tested it, and it worked like a charm.

I'm interested in finding some sort of box/weir type system that i can put it in to tidy up the look of it. oh, and i need to design, buy and build the sump too.

Chris