Pond Boss
Posted By: grasscarp Homemade diffuser - 08/04/11 06:27 PM
This homemade diffuser was deployed today and seems to be working great. Used a 5 gal bucket, plastic pasta strainer, sump pump check valve, sizing adapters, and garden hose.

Drilled hole at base with wood cutting bit, then used hose clamp on the inside to hold it in.
[img]http://photos.feiste.com/GalleryFilmstri...hoto&ci=008[/img]

Used circular piece of plastic from butter container to block some of the center holes of strainer.
[img]http://photos.feiste.com/GalleryFilmstri...hoto&ci=008[/img]

Strainer into buck upside down. Got lucky in that it slide just over half way down before taper of bucket stopped it.
[img]http://photos.feiste.com/GalleryFilmstri...hoto&ci=008[/img]

Filled up around sides of strainer with large white gravel, then topped off with pea gravel. Drilled 1/2" holes around side where large gravel lays to allow water in.
[img]http://photos.feiste.com/GalleryFilmstri...hoto&ci=008[/img]

Using garden hose weighted with rebar and brick the diffuser was deployed at a depth of 6 feet, and attached to a Medo LA-100. Creating nice diameter bubble column. Will take under water pictures with fish camera next time what is clear.
[img]http://photos.feiste.com/GalleryFilmstri...hoto&ci=008[/img]

Expensive diffusers and weighted line would of course be the ideal setup, but for around $20 I am happy. The LA-100 is very quiet and uses less power than a 100 watt bulb. Hopefully the rig will provide much needed O2 to the fish.
Posted By: Bill Cody Re: Homemade diffuser - 08/04/11 07:14 PM
This diffuser as with many other homemade ones will produce bubbles. I have been exploring homemade diffusers since 1984. The technology of diffusers is always advancing. Not to be negative, but comments are ment to be educational and thought stimulating about building diffusers.
These items are what I see lacking in this unit.
1. Too big of bubbles. The smaller the bubbles the more water that is moved and vice versa. Holes in strainer are too big and when moving up through the pea gravel the bubbles will tend to coalese and form even bigger bubbles thus making the unit even less efficient.
2. Unit with all that gravel, weighs much more that other types of units.
3. Base or bottom is too narrow or small thus making it more vulnerableto tipping over in soft sediments.
4. Unit is not any less expensive than other more efficient homemade diffusers.
5. IMO the unit should have some sort of check valve esp if it is not run 24/7.

For homemade diffusers I prefer perforated tubing or vinyl hose. Perforations create small holes in hose and some soft materials are resistant to clogging / incrustation. Catch 22 part: Small holes clog quicker than larger holes.

PS:YFI to all: bottom diffuser aeration units are not ment to directly provide needed 02 but intended to efficiently create a strong upwelling currrent and thus 'turnover' the BOW. Intent is to bring 'bad' water to the surface, degas it, and at the surface allow natural oxygenation processes to occur that increase the DO.
Posted By: Bing Re: Homemade diffuser - 08/04/11 07:58 PM
I have always heard that under aerating, or designing and operating a poorly designed or undersized system, or not starting one up properly can be desasterous.

I think the following quote, which is stolen directly from Sue Cruz in todays post called, "All or nothing", sums it up.

SUE CRUZ QUOTE:
Sometimes "under" aerating can cause more problems than not aerating at all ~ you will de-stratify your pond and mix the bottom low oxygen water with the top oxygenated water, but not move it enough to bring the oxygen levels up throughout the water column. I have seen where oxygen levels are sooooo low by the bubble column because the low oxygen water is being brought up from the bottom, a sure sign of under aeration. You really need to circulate the total volume of water atleast one time per day to bring those DO levels up. My suggestion to you is to put it on your list of priorities and plan on a properly sized system when you can find it in your budget. Don't waste money on half a system that won't benefit your pond at all.


Grasscarp, if your system is not of the proper size, etc. you could be creating a disaster.


Posted By: grasscarp Re: Homemade diffuser - 08/04/11 09:46 PM
Thanks for the feedback guys.

Bill, there is a sump pump check valve at the bucket connection. I don't understand how a big bubble working its way through pea gravel will coalesce. Intuition makes me think that a bubble will divide on its way up. Does it reform at the top?

Also, with very fine bubbles I believe there is significant transfer of O2 into the water. I found this neat article that discusses some science around that topic.

http://www.ksn.bio.aau.dk/Semestersider/Aalborg/K8/k8m/WWT/WWT3b.pdf

Bing, I have heard the same thing about under aerating and have done a lot of reading on the topic. I also read Sue's post earlier about under aerating. It also included a section about successfully aerating a single cove in a large lake. We had our disaster last year with a major fish kill at the end of a hot summer, followed by many cloudy days, causing an algae bloom crash. The lake contained about 20 grass carp which all died. Nothing over 4 or 5 inches survived. I always wondered how effective the grass carp where, we found out this summer when weeds/grass took over the lake. Eight new grass carp are scheduled to go in next spring. Chemicals have been applied this summer which has caused a weed/grass crash, similar to the algae. The past 2 or 3 days have been cloudy here in Cleveland which was apparently was enough to drop the O2 because fish were gulping at the surface this morning. We have had a larger system spec’d out, but the cost was an issue. Our lake is over 5 acres, oddly shaped, and shallow in a significant portion. I'm hoping the aerator will at least create a zone of survivable O2 similar to the cove Sue described. If it does we may add a couple more.
Posted By: Bill Cody Re: Homemade diffuser - 08/05/11 01:05 AM
gcarp - I think with, no proof, that as the assent of the bubbles is slowed and when they come in contact with one another on their path through the gravel the bubbles will tend to combine or merge together. A lot of this will depend on how fast the bubbles are rising and how often they come in contact with neighboring bubbles. Some of my opinion is based on the size and shape of the boil in the last picture.
Posted By: Rainman Re: Homemade diffuser - 08/05/11 01:36 AM
Air flowing through the "pea gravel" will channel and not be very effective IMO due to creating "streams" of air rather than fine (<5 micron) bubbles. Pea gravel and the channeling effect would probably create bubbles that could be more in the 1/16 INCH size from what I recall of fluid dynamics.

I would not count on any helpful amount of oxygen being absorbed directly into the water from the (relatively speaking) huge bubbles that will be created here.

If cost and a budget is an issue, you would be way ahead to get membrane diffusers from Diffuser Express in Columbia, Mo. While not the best diffuser you can get, they work pretty well and will be immensely more effective here and not too pricey.
Posted By: Bill Cody Re: Homemade diffuser - 08/05/11 02:40 PM
Try this, buy about 20-25ft of clear vinyl tubing 1/2"-5/8" ID. Punch it full of holes. Actually slits are better than just holes. Test the prototype dry for proper number of holes by checking for any back presure on compressor. Backpresure indicates need for more holes/slits. Coil the hose on a grill rack or similar frame. Coils can be tight or up to 3/4" apart. Mount rack on frame or flat plate.
Posted By: RC51 Re: Homemade diffuser - 08/05/11 03:00 PM
[quote} If cost and a budget is an issue, you would be way ahead to get membrane diffusers from Diffuser Express in Columbia, Mo. While not the best diffuser you can get, they work pretty well and will be immensely more effective here and not too pricey.

[/quote]

I agree with RM on this one. Not that you idea wasn't cool cause it was, but you can get one 9 inch fine bubble diffuser from Diffuser Express for about 16 or 17 bucks. I have 3 of them and they work Great in my 3/4 acre pond.
Posted By: grasscarp Re: Homemade diffuser - 08/08/11 12:30 AM
Thanks for the reference to Diffuser Express guys, new work in the future will likely include their product.

I checked out the homemade diffuser today with a fish camera and discovered that Bill's third item in is comments list was accurate. The unit had tipped over part way and was not operating as planned. Air was coming out of the side holes intented as inlets. The strainer had also slid out of position due to it being tilted. The diffuser was pulled out for modifications. At that point I was wishing I had a couple of those Diffuser Express units. In the meantime I made some changes to this unit. First was to attach a circular metal oil pan to the bottom of the bucket. Second was to add screws in the side to prevent the strainer from tilting. After placing a couple bricks in the oil pan, the unit was redeployed and checked with the camera. All is well now. The bubbles appear frothier and outflow is great.

http://photos.feiste.com/GalleryFilmstrip.aspx?gallery=971975

Bill, thanks for replying with the list of concerns because that movtivated me to check it sooner than later. Membrane diffusers will be coming next.
Posted By: SFCarlock Re: Homemade diffuser - 04/06/12 02:27 PM
Hi Everyone,
Sorry to bring up an old thread, but I'm new to the forum and have some questions about how I could make this diffuser work.
I'm trying to control the algae in the girlfriends mothers pond. They have one horse and are near a lot of farm areas, so I'm assuming it's getting a lot of run off. It's a 1/3 acre 10 foot deep pond, 3 years old.
Could I modify this diffuser with a check valve, a more sturdy base, and stretch a piece of fabric over the top to break up the bubbles more?
Thanks,
Scott
Posted By: Bill Cody Re: Homemade diffuser - 04/06/12 02:49 PM
The diffuser in the above post has design flaws IMO. It does not make efficient use of the air from the 'pump'. Use the check valve to make a diffuser that I describe in the above post. Spend your time building a better diffuser rather than one with a poor design. Or buy a membrane diffuser and mount in on a snow saucer, garbage can lid, or homemade frame. PM me for pictures if necessary.

If excess dissolved nutrients are present especially in runoff water don't expect the aerator to significantly stop filamentous algae growth. However it will improve the overall water quality in the pond which could actually lead to more algae / plants due to the excess nutrients. Without nutrient control, one essentially just exchanges one type of plant for another. Nutrients are the stimulus! As S.Cruze mentioned above a poor diffuser or aerator can sometimes appear to cause more more problems than it solves. Too little knowledge can be dangerous.
Posted By: Johnny MAX Re: Homemade diffuser - 05/31/12 03:59 PM
Looking into a diffuser project and found this thread.
I have some old soaker hose, would that work?
Posted By: Bluegillerkiller Re: Homemade diffuser - 05/31/12 04:19 PM
Soaker hose clog from what I've read.. Membrane diffusers are the way to go and listed above is a cheap place o get them, if not cheaper than soaker hose..
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