Pond Boss Forums AERATION Systems questions Overflow Pipe To Bottom To Exchange Water

Background:

I have an approx. 3/8 ac pond, approx 11' at deepest point.

Pond is almost drained for maintenance.

12" overflow straight through dam at normal water level, piped with bends on dry side of dam to bottom.

Currently there is not electric or funds for aeration

Thoughts:

I want to try to aerate(?) or at least exchange the water when rainwater would cause an overflow.

Thinking of placing a tee on overflow, bar guard in top of tee, with piping down in pond to draw water from or near the bottom. Perforate the pipe and cap to draw water but not debris or fish.

Questions:

Is this method effective?

Is it best/necessary to get pipe near bottom?

Should the pipe be extended out into pond to draw water further into pond?

Is this as effective as a siphon with an air gap?

Thanks.

I don't see why that wouldn't work, at least for removing water from the bottom. To operate well as a siphon, though, consider attaching a vent pipe to the top of the tee and angling it downward so the air intake is near the normal water line as shown here: http://www.ponddampiping.com/syphon1.html

That way during a high water event the water level doesn't have to rise but so high before air is cut off from the vent and the pipe can begin siphoning. You can reduce the diameter down at the tee to 2" or so for the vent pipe.

It is also recommended to have a 45 on the outlet end of your pipe. That will help keep air from being sucked up into the system preventing the siphon from starting.

One other thing... They say you need the outlet end of the pipe to be at least 4 feet lower in elevation than the intake in the pond for it to work well. Not sure where that number comes from, but I'm no physicist, when I built my pond I just accepted it as truth and constructed it accordingly.

If you decide to try this, keep us posted and don't forget pictures!

Scout, Welcome to the Forum!

I'll presume you would extend the inlet side to the pond bottom, or very near it....and to supplement what vamaz just posted.....

Some things to consider if adding to your current overflow system or if you add a separate siphon. Personally, I'd choose the latter.

First, are all the existing pipes and especially the connections 100% leak free? If not completely sealed, it will never siphon properly

Second, unless your tee loops over the high pipe point and then down to the targeted siphon starting level, it may never siphon properly, stop properly or whirlpool so badly it will suck in air up to a few feet below water level that it remains more of a common bottom draw drain pipe.

Third, retrofitting your pipe could end up costing quite a bit more than adding a 4 or 6 inch separate siphon built right and you get to keep your current pipe as a secondary back up. My memory is weak, but I think that when in full siphon mode, a 6" pipe will extract more volume per second than the 12" flow through.

Fourth, the 45* angled pipe aimed upward on the outlet is to prevent/stop the water "flattening" out inside the outlet side of the pip and let air enter from that end to break the siphon. The larger the pipe diameter, the more crucial that angled pipe becomes.

Fifth, ensure a siphon break tube guard is fail-safe on preventing a blockage or you may wake up to a fully drained pond after a rain event!!! One stick and several leaves can suck out years of work in no time!

Sixth, make absolutely sure the outlet at every stage from full flow to simple, slow overflow hits solid surfaces such as large rip-rap or concrete or you could get a new, downstream pond created in minutes from the erosive outflow!

Seventh, that 4' drop is the distance below the water level, NOT the inlet pipe level. The drop is required to create a low enough pressure on the outlet side so atmospheric pressure will force the inlet side through the pipe in an arguably violent force and velocity.

Siphons do a great job when built and installed properly, they are also relatively inexpensive, withdraw HUGE volumes of water, fast, and are pretty low maintenance

Thanks for the replies and welcome. Long time lurker first time poster.

I was thinking using my existing 12" as gravity not siphon, but instead of surface drainage, have it flow from the bottom.

I am impressed with the permanent siphons but a few years ago went with the top gravity drainage, instead of a pipe through the bottom of the dam. Actually, I use temporary siphons, 4" and 1" to drain the pond.

If a siphon were used, I would like to size it so it performed like a siphon and not gravity flow. I have thought about fishing my 1" poly pipe through the 12" and make a air gap like you all suggested.

I thought though since I have the gravity in, perhaps the tee and pipe to bottom would exchange the water trying to improve water quality.

I am positive that with some ingenuity, it could be made into a siphon. Like I mentioned above, at what expense though? And, it has to be completely sealed to work.

You never know when a huge rain may come and excessive drainage capacity can NEVER be a bad thing.