Pond Boss Forums AERATION Should I aerate? Membrane Diffuser with Linear Pump

I have a 25 year old pond once 12 feet deep now 5 feet deep with sludge 99% leaves on the bottom. The size is approx 1/8 to 1/4 acre I just installed a Diaphragm pump with 2, 9 inch membrane diffusers I placed the diffusers approximately 48 inches apart and put them resting on the bottom sludge with cinder blocks holding them down. I blued the pond and skimmed most of the duckweed and algae out now today is my first day running the system. I am wondering should I put a couple more diffusers in and how long will it take to get rid of the fair amounts of sludge. And should I move the diffusers around periodically? What can I expect to happen now? Thanks for the help, I want my pond back.

Chipman

PS I do not have many if any fish just frogs and leeches. I do have tons of exotic trees around the perimiter.

Hi Chipman...i am no expert but i have lots of opinions

i realize aeration is a fantastic way to combat sludge build up but i would be absolutely floored if the aeration experts would chime in on this and tell us all that aeration alone could remove 7 feet of sludge build up in a reasonably short amount of time. my reaction to your post was, drain it, clean it out w/ heavy equipment, and start over. but perhaps that is too radical......?

Chipman,

Welcome to Pond Boss. Here are a couple of links for you to browse. In one link, you will find a post by Sue Cruz in reference to a lake in Michigan. Hope this helps.

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=15;t=000029#000001

http://www.pondboss.com/ubb/ultimatebb.php?ubb=get_topic;f=12;t=000062#000001

Thanks for all the help I hope I can get this pond cleaned up for the end of the season I would liek to put some fish in this year. Does anyone know if I should spray the rest of my duckweed with Reward or bite the bullet and buy the Sonar. Also Can you have to much airation I was thinking of adding another 2 membranes cause these 2 that are in there are really pumping the bubbles. I think I could add 2 more and not affect the blower. Any suggestions please. Thanks again for all the help.

Chipman

Thanks Russ, I am picking myself up off the floor Sue's report on the lake in MI is impressive but the conditions were likely quite different.

I would still wager that 7 feet of muck in a small pond will take a while, I guess I forgot to ask you Chipman, just how soon do you want yer pond back? You mentioned "tons of exotic trees".....I opted to clear all trees within a certain radius of pond edge to minimize muck accumulation and water consumption.....mostly i removed trash willows.

WOW are you saying the trees are sucking up the water from the pond cause I have tons of them around the pond from Jap maples to Larches, cedars you name it all manicured and groomed. I have time to get to the bottom of this pond and I would like to put acouple more membranes in if possible.

First 24 hours of airation and looks like I have some kind of grey brown foam starting to float to the surface is this normal and should I do anything else. I just was getting ready to add some good bacteria and some enzymes. I have skimmed off 85% of the duckweed so the surface water looks clean excepth the little bit of foam. Please advise.

Thanks a million
Chipman

hi chipman, based on yer region, your ornamentals may be fine and i'm sure make the scenary beautiful...i love jap. maples......so if the pond gets plenty of water, rainfall or otherwise, throughout summer (how is your pond fed?) i wouldnt sweat cutting out your nice sounding landscape.

in my region, we get no supplemental water so i had to minimize tree growth especially near shore willows.

sounds like your aerator is starting to do its job, its good you dont have fish in it now as it is probably mixing around your previously anoxic/anaerobic organic matter and liberating some nasty gases. the aeration experts will be able to comment on this much better than I.

This is the time of year that all of us are out in the field. I have to go out right now but will respond to your questions tonight.

Chipman,

Welcome to the Pond Boss. Here it is 9:20 and I am just now sitting down to answer this question.

You are doing the right thing by adding aeration. By circulating the entire volume of your pond so many times per day will ensure you provide the habitat for the benthic organisms and bacteria needed to slow down and if sized properly reduce the muck in your pond.

Dave is right about the time needed to do this. Some companies state that the muck was reduced very quickly by simply adding aeration. In reality, the muck may have just been suspended into the water column.

We have experienced muck reduction but over a greater period of time. If a system is sized for a minimum of 0.75 times per day, and more realistically 1.3 times per day the habitat at the bottom of the pond will become aerobic thereby allowing the habitat needed for aerobic bacteria and benthic organisms needed to facilitate the muck reduction.

The time period to do this is an unknown. As you stated, the pond has taken 25 years to acomplish this build up of muck, which by the way is what ponds do. They eventually fill with muck and become fields. It may take a much as 10 years of aeration to get back to the origanal depths. Now if you add bacteria specifically designed to reduce the muck, that time period may be decreased.

What Manufacturer, type, and horsepower pump are you using? You mention that you are using two 9" membrane diffusers. How are the joined together? Where do you have these diffusers placed? In the deepest section?

Cary thank you for your response. I am using a linear diaphram pump which is
Voltage (V) AC 115 (AC 110/115/120
Frequency (Hz) 60
Rated Pressure (bar, psi) 2.18
Rated Performance (lpm, cfm) 68, 2.4
Rated Input Power (W) 60
Sound Level (dB) 38
Discharge O.D. (mm, in) 18, 11/16
Weight (kg, lb) 6.5, 14.4

I have placed the 9 inch membranes in almost the deepest section of the pond. It is a kidney shape so i put them in the bigger deeper end. I have used 3/4 in funny pipe and the diffusers are about 5 foot deep with a T and seperated about 30 inches. I am getting plenty of diffusion I think I could add 2 more diffusers and still get plenty of bubbles. I have been adding bacteria and enzymes for the last 4 days every other day. I do still have a little bit of duckweed in the pond I have skimmed most of it out but not all of it. Reward or Sonar or Cutrine. I have cutrine on hand have not used it in years. My pond is water table fed so this time of year I am losing pond depth.

Thanks again for the help this site is awesome with all of the knowledge available by so many experts.

Chipman

I have enclosed a couple of pics of my pond delema could someone please look at them and advise on what to do next. Cutrine? Sonar? Reward? I want to get rid of the rest of the duckweed and the tall weeds. I have described the pond in other posts here. Also should I add a couple more diffussers these are cranking the water above the pond about 6-8 inches.

Two 9" Membranes note how much the one on the left is cranking


Weeds growing out on the narrow end of the pond. Should I pull them or kill them. If kill with what?


See the width of the pond is about 40' should I get the airators closer to the center? Do you think I should add another aerator?



The water looks nice by the airators but I can see a bit of algae coming on. I have skimmed off most of the duckweed it was covering the entire pond before I put the airator in last week and skimmed for a couple 8 hours. There has got to be an easier way to enjoy this hole in the ground.

Thanks again
Chipman

I have added some pictures could someone please advise me as to what needs to be done next.

Thanks
Chipman

Chipman, I personally think you have plenty of aeration, but that the diffusers should be closer together to take advantage of the phenomenon of the much greater uplifting of dual aerators placed as in the vertex dual systems. 4ft. seems to be too far apart. Look on line at the vertex systems and the spacing. If you have fish, I would also wait til the winter kills the DW and WM, then put out a smalller amount of chemical to kill the remaining spores. In this case, patience is a virtue. www.vertexwaterfeatures.com/coactive_new.php - 21k here is a link to the vertex, it looks like the diffusers are about 8 or less inches apart.

Chipman, you have enough aeration with the two disc. As Burgermeister mentioned, the diffusers need to be placed a little closer together to achieve the "synergistic lifting" abilities. The disc should be 12" apart from center of the disc to center of the disc.

DW and WM are the hardest to rid your pond of when you are a small pond owner. There are several chemicals out there that treat these plants and they are either a contact herbicide such as Reward or a sestimic (sp?) such as Sonar.

If you use the contact herbicide in a pond as small as yours, a backpack sprayer is the best tool. Apply on a sunny day and by the end of the day you will see drastic results in what you killed and what you missed. Wait 7-10 days and treat the remaining spots.

Sonar on the other hand will require a dosage in the water and once you reach the desired PPB (parts per billion) the plant will start to show a white color due the the lack of Chlorophyl prduction caused by the chemical. Eventualy (4 weeks) it will die off. Sonar is manufactured by SePro. Both chemicals can be purchased at your local feed or chemical supplier.

Good Luck!

Cary Thanks for the help here. Why should the disks be so close I would think you get more coverage by covering a bigger area of the pond. I just ordered 2 more disks for the other end of the pond, But you say this is a waste of money. Maybe I should just move the 2 I have in there closer to the center. I will spray with Reward this weekend. Does that affect the Trees around the perimiter of the pond? Thanks again.

Chipman

When the disc are more than 12" on center, they act independently of each other and you do not achieve the effect of synergistic lifting thereby reducing the number of gallons you are able to lift with two diffusers.

I would try moving the two you have closer to the center and hold on to the two you just ordered. Maybe you can return them if they are not needed.

Your trees should not be damaged by the Reward. Again, Reward (Diquat) is a contact herbicide. As long as you do not have over spray on the trees you should see no effects of the treatment.

If you want a lot of water lift I still say air stones have got to be better than disc type diaphram units. Someone tell me why I'm wrong. I've read that air stones are better and my own experience while not scientific seems to indicate this to be true. I have one of each type and with the same amount of air going through each you can visually see that the air stones have smaller bubbles and are moving much more water. It would seem that maximum lift comes at a given CFM with smaller bubble sizes. I think hands down air stones will create smaller bubbles than diaphrams. Other than under some conditions being less maintenance I can't understand why anyone uses the diaphrams.

I would think the relative size of the bubbles produced depends on the airstone and diaphragm involved.

Hi bz -
All discs (as with stones) are not equal with regard to bubble size and lifting rates. Discs last longer, with less power consumption and promote longer pump life through less backpressure.

With stones there is increased maintenance which can tend to be a time-consuming hassle, not to mention dealing with Muriatic acid is not pleasant or particularly safe…

Our discs have smaller holes, creating smaller bubbles that require less air to move more water.

bz you are correct about the greater circulation created by the stones. Even the OTR and OTE are better (oxygen transfer rates and oxygen transfer effency) than the membrane disc. This is proven in the Design Manual-Fine Pore Aeration Systems by the EPA.

The problem comes when the stone is clogged. Not many home owners want or even check the diffusers once they are installed. If bubbles are coming up, they think it is working properly.

Membrane disc were originally designed for wastewater use. Since they are able to handle the harsh water, they were a perfect choice for dirty lakes. The disc are limited by the number of holes punched, the size of the hole and the amount of CFM pushed through them.

The new technology in diffusers are a set up like the stones. The number of outlets for air to release is only limited by the lenght of the diffuser tube. Instead of only 6600 slits on the surface per 9" disc, 0.5mm bubbles are released 360 degrees around the diffuser. OTR and OTE are greater than the stones and the disc, thereby not only encouraging greater circulation rates but they are quicker at reaching the desired oxygen levels.

It is all about feeling confident in your system and if you are able to provide the maintenance required to keep the system working properly. It is up to the company that you will be purchasing the system from to educate you about the differences in all systems and allow you to make an informed and educated decision on what is best for your application.

Thanks Cary, makes sense. I figured the real draw to membrane diffusers was maintenance. I haven't had problems with air stones however. I keep an eye on the back pressure required and if it starts to rise I replace the stones. I replaced them once in 5 years only to find out that my gauge was bad and the stones were fine. I suppose how long they stay clean has a lot to do with what's in your water.

For what its worth I just sprayed Weedtrine-D over the whole surface of the pond to try and get rid of the duckweed. Should I add Cutrine now or should I wait and see what the Weedtrine does to the pond first.

Thanks for all the help.

Chipman

Chipman, Wait and see

I now have a bunch of brown duckweed floating on the pond at what point is it safe for me to go into the pond and move the airators. What i going to happemn to the floating brown Duckweed. Please help me I am drowning in duckweed.

Chipman