Drilled PVC Internal Overflow

[WildFoxMedia]

I realize the title seems to imply multiple different types of overflows - but I wasnt sure what else to call it.

Can anyone see a reason not to use an overflow like: http://ovas.ca/index.php?PHPSESSID=af75e0332c9db2f6e3ae3dccea8a6969&topic=32489.msg207453#msg207453

I looked into doing a Coast to Coast, or that type of overflow that stopped a few inches short on each side for the returns - then I saw this. It seems so simple and elegant - not to mention adjustable.

Edit: To stop a fish or invert from getting stuck in the overflow, I was thinking of taking some gutter guard or mesh and wrap it over the top of the overflow.

 

[uncleof6]

The most honest information that I have received, on this type of overflow, from someone that observed the overflow in operation, was that it is an extremely low flow device. This confirmed my assessment, having only seen the design for the first time. I expect, that the slit PVC pipe, if the flow rate was raised, would be overwhelmed, suck air, and pretty much behave as any other air/water mix type standpipe. For this to work well, the flow would have to be low enough, that the water poured calmly into the slot, or the head height would increase, making the drain a siphon, which would rapidly lower the water level. But since, by design the slit PVC pipe has to be at the surface of the water-- to do any surface skimming, it will not become a siphon: because it will suck air, just as a Durso does.

If you want a very low flow system, I am sure it will be fine.

Jim

 

[Qwiv]

I tried one of these on a frag tank I made and it worked nice. uncleof6 is wrong. It works just like an overflow would of the same given length and the same height of water going over the overflow. If you can't get enough water in the pipe, widen the cut. You will still have all the noise associated with a regular overflow. You can make it a modified durso by putting a T on the back side of the tank and installing a cap with a small hole in it just like a durso. Works pretty good and will drain the same as an overflow the same length, limited by the size of the 2 drains holes you need. You will need the gutter guard if you have fish and push a lot of water over it.

I ended up ditching it and installing 1/4 of a large ABS pipe siliconed to the back glass because I wanted to convert it to a herbie style overflow which isn't possible with this set-up. You can't get the siphon right and you also can't install a back-up drain unless you put another hole in your tank. Mine was already tempered after I drilled the holes.
I also didn't like that is stood away from the back wall. Fine for a frag tank but it would bug me in a display and in makes a silly shadow line.

What size tank, how long and how many gph you thinking.

 

[WildFoxMedia]

Its a 29 gallon - 30" long.

I'm not worried about pushing tons of flow through the sump, in fact I've heard that you dont want to put too much through a sump anyway. Any additional flow needed in the tank will be provided by powerheads.

Originally I was considering a $15 PVC pretzel overflow that was posted in a DIY thread here not to long ago. Then I considered a glass coast to coast overflow with a bulkhead at each end and doing a herbie. Then, finally, I saw this overflow and saw that it was easier to put together, after drilling the bulkheads - no getting glass cut or having to silicone it in place. All in all, if the PVC slit overflow wont work, then ill have glass cut, etc.

With that in mind, any basic guidelines on glass overflow weir size when doing a herbie?

 

[uncleof6]

There is an overflow calculator on RC's front page. It is a good enough model to determine the length of the weir required at a given flow rate. Just know that this is without teeth in the weir. With teeth ~ double the length. Also know that the longer the weir, the more efficient the surface skimming will be (lower head height before the weir,) and quieter, at a given flow rate. Also the pipe diameters given are way off for a siphon system (flow rate way low), and far too optimistic for durso type modified standpipes, (without problems.)

Tis all physics, my favorite topic....

Jim

 

[stugray]

It sure works for me.

This is the second time I have tried it & this one can handle all of the flow from one of my Megaflows from my 125G upstairs.

Stu

 

[Rybren]

Stu,

I'm in the process of putting one of these on my 75. I notice that the slit on yours appears to be off TDC. Any reason for that or is it an optical illusion? My second question is on the size of the slit. Yours appears to be about 1/4" is that about right?

Thanks

 

[WildFoxMedia]

Welp - I managed to find 2, 1" bulkheads in this town after much searching.

I did not however, find a single diamond hole saw. I ended up ordering one on ebay from lau***

stugray - could you post some more pictures of your overflow?

 

[flyyyguy]

There is an overflow calculator on RC's front page. It is a good enough model to determine the length of the weir required at a given flow rate. Just know that this is without teeth in the weir. With teeth ~ double the length. Also know that the longer the weir, the more efficient the surface skimming will be (lower head height before the weir,) and quieter, at a given flow rate. Also the pipe diameters given are way off for a siphon system (flow rate way low), and far too optimistic for durso type modified standpipes, (without problems.)

Tis all physics, my favorite topic....

Jim

You can remove as much water with this type of overflow per linear foot as you can with any overflow. Just have to pipe it properly. Its not a siphon....that tank is drilled isnt it stugray??

 

[flyyyguy]

It sure works for me.

This is the second time I have tried it & this one can handle all of the flow from one of my Megaflows from my 125G upstairs.

[

is this an overflow in the sump??

 

[stugray]

"I notice that the slit on yours appears to be off TDC. Any reason for that or is it an optical illusion? My second question is on the size of the slit. Yours appears to be about 1/4" is that about right?"

It is off TDC. I can twist the pipe to adjust the height in the tank.

It is 1" PVC with a slit about two times the width of my tablesaw blade.
I use a sled to make the cut with the pipe screwed down.

Here's a pic a little further back.

The tank is drilled on the side and I have a gate valve that controls how much water goes thru the frag tank.

Stu

 

[WildFoxMedia]

Stu,

How much flow would you estimate your pushing through it?

Have you had any issues with siphons being formed? I imagine if you turned the slit too far horizontal you would run the risk of creating a siphon.

Is it quiet?

 

[grinner30]

Following thread, how has this worked out for you?

 

[phhbrown]

I'm considering one of these overflows and am also interested to know what amount of flow and diameter of pipe is being used.

Thanks