41 replies to this topic

[DoDad]

Does anyone here aerate there pond in the summer? Not counting waterfalls. If so why? If not why not?

[koikeepr]

I do. I have a Dolphin AV-50 with a two air discs in my lower pond and 1 disc in my upper pond. These are on all spring and summer for two purposes. First to keep the water from stratifying and pumping oxygen in; and 2) because I'm trying to move and debris toward my retro bottom drain.

[nc0gnet0]

I have a large air pump that I used when treating my pond with PP and had to shut down my bio-filter. It's on standbye and a must have IMHO. it's capable of working the water nearly to a froth (its an old large vet nebulizer pump for horses) with three 12" air stones attached.

Other than that my waterfall (which is oversixed for my pond) and two ornamental spitters supply more than enough 02.

[koikeepr]

Waterfalls do not plunge air deeply into a pond as does an air stone at the bottom of the pond. Waterfalls, spitters and fountains are all surface action. To add oxygen where it's most needed, which is the bottom 1/3 of the pond, you need to get down in there. See another one of my typically bad illustrations for an example. The first photo is of a waterfall or fountain. As you can see the water at the bottom is not disturbed:



Next, you can see what an air stone or diffuser disc does to the water:



Big difference!

[nc0gnet0]

Well for deep ponds, greater than say 5 feet you have a point. But, you missed out a couple of key elements in your drawing. And I would like to add that while your run of the mill ornamental garden spitter or even fountain may have little penetration, a water fall can be different depending on design and flow.

[nc0gnet0]

For instance my water fall is three tiered. This results in greater oxygenation. The distance from the point of the last step until it hits the pond surface is about 14 inches which results in greater penetration. The pond pump sits on the bottom pulling the water from a low oxygen area and reoxygenating it. While "spitters" might only add a bit of 02, if their pumps are on or near bottom they aid in this circulation. If your turning over your pond volume 2x an hour, there is not going to be a huge differential in oxygen levels.

Admittedly the dynamics change as pond depth and volume increase.

[nc0gnet0]

Addtionally, the most (not all) oxygen that airstones do put into the water happens at the surface when the bubbles burst and agitate the water, and not at the bottom of the pond. All those bubbles are pretty, but the fish can use them until they pop and diffuse into the water.

However, the dynamics change quite a bit when you have an airdome around a bottom drain

[koikeepr]

it's not just about bubbles popping under water...it's about moving the water about to eliminate dead spots of water and breaking up the stratified lower level where the least amount of oxygen sits.

[nc0gnet0]

Quote

it's about moving the water about to eliminate dead spots of water and breaking up the stratified lower level where the least amount of oxygen sits.

We just said the same thing in a different way your drawing is missing the pump that is feeding the waterfall/fountain. If it is a pump sitting on the bottom of the pond it is accomplishing the same thing. That is why a spraybar powered by a bottom fed pump is more effective than an airstone.

[DoDad]

I have to disagree with some statements.
Research has shown that the most efficient aeration is achieved from the pond bottom using a fine-bubble diffuser.My moving bed filter supplies oxygen too.
My research:D I have a aerated moving bed filter which runs 24/7 plus a waterfall and stream that has 6 drops. I tested my water for oxygen saturation before I turned on my diffuser and the readings were very good(6 mg/l) Oxygen after turning on the aeration in the pond the next day read (9 mg/l). The test were made at the same time of day and the water temps were the same.( 70 F)

[koikeepr]

i agree DoDad. I have a disc diffuser on my pond floor that has fine bubbles. The disc has to come from the absolutel bottom to really have any positive effect.

[nc0gnet0]

But are these diffusers near your bottom drains? I said before that air domes around bottom drains was a diferent can of worms entirely......

Quote

My research I have a aerated moving bed filter which runs 24/7 plus a waterfall and stream that has 6 drops. I tested my water for oxygen saturation before I turned on my diffuser and the readings were very good(6 mg/l) Oxygen after turning on the aeration in the pond the next day read (9 mg/l). The test were made at the same time of day and the water temps were the same.( 70 F)

I would like to add at the risk of sounding argumentative that this test proves that your diffusors are indeed adding dissolved oxygen to your pond, I never disputed that. But wouldn't you need to turn the waterfall off and test to make the statement that the difussors are adding more 02 than the waterfall?

I have a fealing I am being misunderstood here. Now if you were to take koikeepers drawing and assume that the waterfall was being fed by your typicall pond in a box skimmer setup that is drawing water from the top layer of water, her claim would be spot on. What I am saying is that if the pump that feeds the waterfall/feature is on the bottom this changes things dramatically. Even with airstones, the majority of the oxygen gets added to the water at the pond surface, but the movement of the bubbles up the water column introduces cirulation, mixing the top layer of oxygenated water with the lower layer of oxygen depleted water. But so does a pump that draws water from the bottom. And yes, the finer the bubbles the better I agree there.

[nc0gnet0]

This is what I was trying to say:

http://www.venturako.../subcat255.html

[koikeepr]

I think we're all violently agreeing. LOL!

[DoDad]

Well I ran the 1st test with the ponds waterfall running, the second test was with the diffuser and waterfall running so why did the O2 increase with the second test?

nc0gnet0 said:

But are these diffusers near your bottom drains? I said before that air domes around bottom drains was a diferent can of worms entirely......



I would like to add at the risk of sounding argumentative that this test proves that your diffusors are indeed adding dissolved oxygen to your pond, I never disputed that. But wouldn't you need to turn the waterfall off and test to make the statement that the difussors are adding more 02 than the waterfall?

I have a fealing I am being misunderstood here. Now if you were to take koikeepers drawing and assume that the waterfall was being fed by your typicall pond in a box skimmer setup that is drawing water from the top layer of water, her claim would be spot on. What I am saying is that if the pump that feeds the waterfall/feature is on the bottom this changes things dramatically. Even with airstones, the majority of the oxygen gets added to the water at the pond surface, but the movement of the bubbles up the water column introduces cirulation, mixing the top layer of oxygenated water with the lower layer of oxygen depleted water. But so does a pump that draws water from the bottom. And yes, the finer the bubbles the better I agree there.