Pond Boss Forums AERATION Systems questions Enough Aeration / Calculation?

Purchased our house in the summer of 2017. Has a .41 acre pond with existing aeration. Slopes fairly quickly with max depth of 7-8'. Pump is a Hi-Blow HP80 with about 150' total of 1/2" line currently with a 9" stone diffuser. (100' poly in ground, 50' weighted in water) Pond is a fairly perfect oval. Always have ran it 24/7 spring through fall, then pull it to shallow water and run occasionally during winter.

[img]https://imgur.com/a/LyXKSNu[/img]

I THINK to get pressure I calculate .433psi per foot? Puts me around 3psi? If correct, I'm flowing 2CFM based on the chart?

Calculations correct? Decent flow for size of pond? Considered upgrading to a better diffuser, worth it?

If you do not have a pressure gauge, you should consider getting one. I would estimate that you have the 3 psi (due to water head above the diffuser (7foot x 0.433), but you also have to consider that the diffuser may add and additional 1psi of back pressure, plus the pressure loss in the 150' of linie (maybe another 1/2psi) This yields about 4 to 5 psi. According to your pump curve, that put your system at a 1.5CFM air supply. A pressure gauge at the pump would tell you for sure without the assumptions, but 4 to 5 psi will be a very close estimate.

If you do not have a lift rate for your diffuser, the rest of my rambling will get fuzzy and may not apply to your system. AND, the lift rate chart for the Vertex brand (the only lift rate chart that I am aware of) gets some doubt from some of the more experienced members here. At any rate here is the lift rate chart for Vertex. I will assume your diffuser is like the "XL1"...



Your system at 1.5 CFM is 0.5 CFM more than this chart was created with so your lift will a bit more than the following calculation (IF the "XL1" equivalence assumption is true).

At a diffuser depth of 7 feet, the chart indicates that you get 1200 gallons per minute lift...that yields (1200gpmx60{min/hr}x24{hours/day}) 1,728,000 gallons a day. Your pond is likely in the range of 1-1/2 to 1-3/4 million gallons total. So, you are making the One Turnover per Day goal. I'd say that you are doing fine with what you have IF your diffuser is near the performance of the Vertex XL1 as indicated on their lift rate chart and my assumptions for other pressure losses are close. Your diffuser should be located in the basic center of the deepest part to maximize the turnovers.

It's impossible to say that upgrading the diffuser will improve the system without empirical data on the alternate brands which seems to be non-existent. Be careful, some diffusers add more back pressure than others which would lessen your effectiveness.

All in all, your systems appears to be just big enough to meet the minimal one turn-over per day. Without finding the best/better diffuser, the next step would be to get a bigger pump that could supply more CFM/Pressure and add two diffusers. At this point, your 1/2" lines are on the small side. The downfall would be that you new pump would have to work harder than necessary, but you could probably double your turnovers.

Thanks for the response and info!

The lines were 1/2" buried to 3/8" weighted and I upgraded to 1/2" because I was worried about the restriction.

Anyway, sounds like I'm in decent shape. I'm guessing flow is flow so doing a dual head diffuser is not going to help compared to a single?

And is the Matala comparable, or worth the savings, to the vertex? I'm guessing a membrane diffuser WILL be an upgrade to my current stone.

Now that you mention it, a double head diffuser, like the vertex XL2S, could give you some improvement. Vertex states that their lift chart was developed with the "Air Flow = 1.0 CFM (cubic feet per minute) per disk". With that said, they claim that a double head diffuser actually doubles the lift. What we do not know is what happens if you double the CFM for one diffuser. My suspicion is that air flow beyond the 1 CFM per disk actually swells the membrane so that the slits open up further causing the bubbles to get larger which is thought to lessen the lift results. In other words... the increase in lift in not linear to the increase in CFM when considering just one diffuser. IF that's the case, adding a double head diffuser, even though they will not be operating at 1 CFM each, should give you some more lift. This is a good assumption given that the back-pressures are the same or better when comparing the old diffuser to the new. You have found yourself on that fine line that could go either way and you would not know if the modifications made an improvement without a lot of bench testing.

I would physically look at your boil and compare it to some videos of other adequate systems and see if they look the same. Not very scientific, but at least it will let you know if the violence of the boil is in the ballpark. If so, I'd say leave well enough alone until you want to take it to the next level.

Glad to help out here where I can and I enjoy talking aeration theory and beyond.

OK... now I can't make a damn decision, lol. I was pretty set on the Matala diffuser based on good reviews, low back pressure, and a great price. I was trying to decide between 1 - 9", 2 - 9", or the 12". Called a company and he recommended the single 12" based on my info. However, I then came came across youtube videos of a company that show many of the diffusers under water and it is very obvious the Vertex has much smaller bubbles than the Matala. So, i then have been trying to decide between a single or double Vertex. However, in many threads, including the current one at the top of this category on the forum, it seem the vertex have substantial back pressure and many get a high reading. With my pump, I'm wondering if it can handle the Vertex or if I'm forced to go with the Matala..

Go with the Vertex dual head. You'll be happy you did. The Hiblow pump you have has more than enough power to run it.

Thanks buddy. Exactly what I wanted to hear. Just so happens to be one craigslist locally.

Ibanez, Did you get it going yet?
How's it working for you?

Hey! Yes I did. Flow and bubble production looks good. I do not have a pressure gauge hooked up, but when I was struggling to connect the hose to the diffuser with the pump still running, everytime I'd pull the hose from the nipple I could tell there was definitely a fair amount of back pressure and air that would come back out of the diffuser. This did not happen with my stone diffuser.

But, so far so good. Hopefully it doesn't put more strain or wear & tear on the pump.

Once you've gotten the pond broken in, I highly suggest you take temperature readings from top to bottom. If you can create a thermocline under your diffuser, great! If there is no thermocline, then once the top and bottom temps match or get real close, then you can back off on run time until those temp differences start getting bigger. What I'm saying is, why run your pump 24/7 if 6 hours gives you a complete turnover and saturates the pond with DO. The remaining 18 hours let's the depths cool and creates a deep, inhabitable haven from the heat and you're not overworking your pump, or burning electricity.

Elaborate? I thought the point of aeration was to NOT have thermocline?

There are two schools of thought regarding thermocline. The first is that since thermocline exists naturally in large, deep BOWs that maybe they should also exist in a pond. To do what they are intended to do, to provide an anaerobic area in water for decomposition. A body of water's natural process is to fill with sediment and eventually cease to exist. It also provides a cooler area where fish can escape to when temperatures become too stressful. They cant live down there, because it is virtually void of oxygen, but they can visit the area to destress. When using a depth/fish finder, if you have the sensitivity set correctly, you will see the thermocline on the graph, as well as fish holding right on the ceiling of it.

The second school of thought is that by eliminating the thermocline in a BOW, you convert the anaerobic process into an aerobic process. By infusing DO into every layer of water right down to the bottom. This process helps to reduce the buildup of muck by helping bacteria to break down the organic material, and eventually be displaced through gases as its brought to the surface. The stocking of fish that feed on detritus also helps to reduce the organic solids since now they, and all your other fish have full use of the pond. The trick in this thinking is having almost constant knowledge of the pond's water temps and adjusting run times to prevent super heating the entire pond. If your pond is off site, and you cant visit it often and make necessary adjustments, you could likely drive up on a pond full of dead fish.

The depth/layout of your pond, and the placement of diffusers will determine whether you can fully aerate the entire BOW. Elevated diffusers tend to leave a couple feet of dead water (thermocline) under them, unless you remove the bottom plate, which allows water to flow up thru the diffusers range of lift from below it, bringing detritus up with it.

Ponds set up to maintain a thermocline tend to be clearer, whereas ponds without a thermocline tend to be more turbid.

That's the way I understand it, anyway. If I missed something, or are off base, I'm sure someone will correct my misunderstanding.