Pond Boss Forums AERATION Systems questions Should I add water at the surface, or below?

Water to our pond has always spilled out of pipe at the shore, splashing into the pond. There is a lot of energy since there is a significant length and elevation drop to the pipe.

Would it be beneficial to extend the pipe to the bottom center of the pond, and have the water introduced that way? There is enough pressure to push the water through since the pond is only 12 feet deep. Would this improve the water quality without doing aeration?

Or does the "splash" method at the surface add some aeration that a bottom introduction would not?

Billy,

This thread provides some of your answers. I would especially take a look at Rainman's suggestion of using a venturi to add air to the water stream before it is released in the bottom of the pond.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=460748#Post460748

You might consider this illustration, scaled up in size to better handle the inflow-volume.

Water chemistry also plays a role if oxygenation or pre-treatment is needed when adding supplemental water.

Bronco if the water is cooler spring water it will sink to the bottom displacing the warmer water anyway. In that case I would keep it at the surface. The pond surface gives you the most oxygen, moving the surface water helps mix it. If the water is air temp already you may want to try something what like Kelly has shown. The goal is to move water with your incoming water.

In my case I have spring water coming in. At first I ran a 4 inch corrugated plastic pipe down to the bottom. I had to weight it down as air would get trapped in it. After awhile the air built up and the water would just back up the pipe. I now have it going through a 10 inch culvert at the surface that is open on each end. Air flows through the pipe with the water oxygenating it. It enters the pond at the surface and then sinks to the bottom. DO tests show this is best for my pond.

If you try to have it enter the pond at the bottom you will need to collect the water into a pipe much higher then the pond surface. You will need that head pressure to make it flow. Design it that there is no place for air to be trapped and use only smooth pipe.

Be very sure you have the chemistry and effect on plankton figured into your choice. If the effect of the water input is to kill or reduce the plankton (major source of O2) then even if it has enough O2 it may cause a big problem.

Kelly, I like the diagram!!!

I thought the same thing Esshup! Nice illustration.

Home made venturi.

I think I need to learn about the water chemistry and get some equipment to be able to test it. I know zero about this so far.

The diagram is very nice. Easy to understand. I'm not exactly sure of the purpose of the hose barb, or if the same system would work without a hose barb in place?

Is the purpose of the barb to reduce flowing water volume and increase pressure, enhancing the ability of incoming air to be able to mix with water? Or is it to create suction? Or both?

The barbs are key to making it work. Effectively, the purpose of the barbs is to decrease the cross sectional area which will increase the velocity of the water which produces a lower pressure. The lower pressure will actually cause the air to be "sucked" into the flow at this point. It is called the venturi effect.

I can tell you my experience with using a venturi. First off you need enough water flow to make it work. As Kelly noted, scale up the diagram. If you would use the scale in the diagram with stream water, debris will plug the 3/8 hose barb and the party is over. I have found that a 2" venturi is about as small as you want to go. A 2' venturi in a 3" pipe will work. You can use a much smaller air inlet then the size of the venturi, I used 1/4" hard plastic tube in a 2" venturi. Its all about water flow not just water pressure. You can see this effect whenever you drain a sink or a bath tub, at some point air sucks down into the flowing drain. This is the swirling tornado of air you see. Obviously the more pressure and the higher the water volume, the more air you can inject. If you can build the venturi out of clear pvc you can see it working.

First find out what size pipe you can keep full of water with your current flow. Use the largest pipe size you can. Next build a venturi to reduce the pipe size a bit cut your large pipe and insert it. Drill a small hole in the venturi for the air inlet pipe. Cut the end of the air inlet pipe at an angle and face it down stream. The tip of the air inlet pipe should be sticking into the venturi. Your venturi can be on shore where you can play with it to get the best results. The angle of the venturi vertically or horizontally makes no difference

This is actually easier to make work the one would think. It's a fun project to play with also. Because the water pressure (head pressure) and flow rate are unknown you cannot apply any formula for venturi size percentage that will work most efficiently in all cases. Experiment and have fun with it.

My venture works great. In my situation, I have thick walled 2"ID Flex tubing running from a water well that produces 65 gpm @ the well head. The well water has a 7.2pH. Water hardness is 20ppm which is a little low for raising fish so I add agg lime to increase the water hardness as needed. I am at 50ppm hardness in the pond. To add air to the well water before it enters the pond I laid the 2" Flex tubing on the ground (12 feet from the end of the tubing) and drilled a 3/4" hole into the top side of the thick walled tubing. I then cut a 6" piece of 3/4" steel pipe and using a grinder I ground a 45 degree cut on one end of the 6" pipe. I then drove the ground end 3/4" pipe into the drilled hole in the 2" tubing until the 6" tagged bottom of the 2"id tubing. Keeping the 3/4" pipe longer side cut upstream. This causes the water to pass around the 6" on both sides and will make a suction in the 6 pipe, where air is sucked into the water before it hits the pond. I can place my finger over the top of the 6" and not only do I feel the suction but the water coming out of the two inch looks to be aired up or frothy looking when the finger is removed from the top of the 6 pipe. I will also let the water hit some rocks at the water edge for additional splashing to add some more air. I am no expert but this worked for me and maybe it will work for others.

It would be very cool to see some pics and videos of some venturies working.