Disc Diffusers, Airstones & Silica Diffusers
All bubblers are not created equal; use the right diffuser for the job
See our recommended diffusers for aeration

Of course the heart of any aerator has got to be the compressor, linear air-pump, regenerative blower or windmill bellows but let's not forget to look at the myriad array of diffusers. The diffuser is what breaks up the airflow into bubbles! Big bubbles, small bubbles and even micro-bubbles or ultra fine bubbles all can be used to achieve different results. Just like a home stereo system can sound great through a set of high quality speakers even if the turntable is marginal; so too can a proper diffuser make an old home-made air pump actually create some decent aeration!

Many aeration supply firms and pond stores sell cheap diffuses and some of these are just that: cheap! Maybe they'll last a year or maybe two, but as with any part of the aeration system, whether it is changing the worn out pistons on a Gast compressor or replacing the worn carbon vanes of a Brookwood compressor, a diffuser may need periodic cleaning with muriatic acid. A good diffuser assembly can be a weighted disc system like the Vertex CoActive Air Station with 2 nine inch diffuser discs on a hollow base that can be filled with rocks to keep it on the bottom or a Koenders Airstone which is simply placed in to a bucket with some stones and lowered in to the pond. There are also many knock-offs of high-quality diffusers by companies trying to market a poorly performing copy of a brand name technology in order to garner greater profits. Let's look at some of the different pond diffusers:

You want to build a home made diffuser?
No you don't...you only think you do! The idea of scrounging through the tool shed for some pits of PVC pipe or hose and some metal jugs or gathering buckets and attempting to fasten a sealed skin from some recycled EPDM membranew might sound like a good idea but it isn't. Sure you can take some SCH 40 pipe and drill some holes in it and cap of the end and epoxy glue a 3/4" NPT air supply connector and make some contraption that will release bubbles but that doesn't mean you will have an efficient diffuser.

The best difuser is one that uses the available airflow and horsepower to maximum efficiency but breaking up the air into bubbles...but not all Bubbles are created equal. I know...it sounds discriminatory but it's the Truth! In most cases you want to have small bubbles and the smaller the better. Ultra-fine bubbles or micro-bubbles as they are sometimes called in the industry are what creates the most efficient aeration.

Much of the actual oxygen transfer in to your pond or lake actually occurs at the atmosphere/water interface where water is introduced to the atmosphere by being pushed towards the surface by the rising bloom of bubbles. As the water breaks the surface tension of the pond or lake the oxygen transfer occurs and the water, now with higher levels of vital oxygen, descends back in to the depths where it causes dissolved O2 levels to be higher and higher depending on temperature and baromteric pressure among other variables.

But that doesn't mean you can just drop an open ended length poly irrigation pipe running in to the pond from the end of a tire pump and expect these basketball sized bubbles to create enough lift to properly aerate...no...it's not that simple because the bubble size also plays an important role in the Gallons Per Minute lifted towards the surface and the important oxygen transfer that occurs betwwen the thin walls of the bubbles themselves as they stream upwards from the diffuser towards the surface. Yes it is a multi-faceted process and while it may be sounding too complex there is a simple rule that applies to most pond diffusers...

Smaller bubbles are better bubbles
Let's have a brief lesson in fine bubbles, it will be fun (well...not exactly) and you will get a short course in why smaller is sometimes better especially when it comes to diffuser bubbles!

Lesson 1
Let's take a fairly large bubble as far as aeration goes. Our large galloping bubble that is 0.8" in diameter, just over 3/4 of an inch, or 20 mm has a full volume of 1.64 cubic inches or 4.19 cubic centimeters. This same glorious orb has a surface area of 5 inches or 12.6 square centimeters and that is what we can define as a coarse bubble!

Lesson 2
Now a coarse diffuser like an airstone would create large bubbles like in lesson one but if we could use the same volume of air but break that large sphere into smaller ones we could greatly increase the available surface area which in turn enhances and embellishes the aeration transfer capacity of the same air volume! If we replaced that one large 3/4" wide bubble with tiny bubbles or micro-bubbles that were 1/16 of an inch or 3 mm in diameter we could fit 296 of these fine bubbles into the larger one of lesson 1! The combined surface area of those 296 bubbles works out to over 33 square inches or 84 square centimetres! This is close to 7 times the total surface area...and the surface is where the oxygen transfer occurs.

Lesson 3
Now since the surface area is close to 7 times greater we can theroretically aerate 7 times as much water with the same compressor or blower or air pump depending on whether we have a fine bubble diffuser or a coarse bubbler. Same air pump, totally different efficiency!!

 
The Best Rated Diffusers

Diffuser Discs
9" Membrane Disc Diffusers
Normal airflow range is 0–5 cfm. Equipped with 3/4" MNPT. Single disc or multiple discs can be used with linear air pumps, piston pumps, rotary vane pumps or regenerative blowers. Ideal for everything from small ponds to large lakes. Contact us with questions.
Item # PR-ED3271

Practically invisible due to their dark color, these 9 inch membrane discs are engineered for extended performance. The actual disc diffuser bodies are made of high-strength polypropylene with 3/4" MNPT connections to attach to airlines, manifolds or headers. Each diffuser has an avergae of 6,600 engineered air release orifices, 20% more than some comparable models. The special design of the matt, flexible and supple EPDM membrane, with its proprietary thickness taper, results in full utilization of the membrane surface, even at low airflow operations. This results in improved oxygen transfer efficiency, along with maximum operational flexibility. The disc diffuser has an integral "triple" check valve to prevent fluid backflow. Resistance is about 10" H2O when clean. Made in USA. Note: Diffusers are also known as airstones, these are membrane diffusers with an HPDM fine bubble perforated system.

Tip: With two 9" discs and some simple plumbing parts and fittings you can build your own assembly. Two discs mounted on a weighted base are sometimes called "aerations assemblies" with brand names like the Vertex "CoActive AirStation" or the AquaMaster Aqua Air "Dual Membrane Diffuser" or the Aeration Technologies "Airpod" or the "AirBoost" or the "SCEPMD2"...you see where I'm going? Add two of these 9" Membrane discs and some plumbing on to a cement block or stone and you have a fancy-pants aerator for much less expensive than a brand name contraption!

PONDS LESS THAN 9 FEET DEEP
Over the years we have installed, replaced, cleaned and destroyed a wide variety of pond and lake diffusers. Here we have listed some of the highest performing systems which work in most situations. If you are involved in a special lake project or a more intricate stromwater retention basin aeration project and require recommendations for the best diffusers please email us.

4 x 6" Airlift Weighted Diffusers on a Weighted Base
No need to add sand or rocks in to a hollow base like so many diffusers! These diffusers assemblies need no extra weights! Normal airflow range is 1.5 - 2.4 CFM. Equipped with /5/8" barbed connector. These weighted diffusers lay flat upon the lake or pond bottom so disturbed sediments is minimized and airstones do not become fouled or covered in muck due to the underlay which keeps the airstones out of the sediment.
Item # PR-ALA4GL1

Some of the smallest and finest bubbles available in any diffuser means that you get the most lifting of water column towards the surface and less pressure loss during operation. These diffuser assemblies require less PSI and so are perfect for linear air pumps in most ponds! Can also be used with rotary vane compressors or piston compressors for a simple and easy aeration system. Contact us if you have questions or unsure how many to add to your pond.

Price per unit versus efficiency makes for an interesting comparision to such diffusers as the Vertex CoActive AirStation The fine bubble production of the bonded silica diffuser assembly which releases the most ultra-fine micro bubbles than any other medium price range diffuser we tested.

MOST EFFICIENT DIFFUSER FOR DEEP PONDS & LAKE AERATION
Six-Diffuser Synergistic Glass Bonded Silica Assemby
Each of these 6 diffuser airstone assemblies has a weighted base and plastic underlay which perevents sedimentary erosion during operation. For ponds and basins from 8' to 40' deep. Equipped with barbed PVC airline inlet. Requires between 3 - 7 CFM for optimal operation.
Item # PR-ALA6GL1

Some of the smallest and finest bubbles available in any diffuser we tested means that you get the most lifting of water colum towards the surface and less pressure loss during operation.

Price per unit versus efficiency makes for an interesting comparision to such diffusers as the Vertex CoActive AirStation XL and the new XXL with five discs or the AquaAir new competitive 4 disc diffusers. Neither of these competitive lake-bed air diffusers come close to the fine bubble production of the bonded silica diffuser assembly which releases the most ultra-fine micro bubbles than any other medium price range diffuser we tested.

9" Airstones
9" Airstone with 1/2" NPT connectors
Air Diffuser, 9" L x 1.5" W, 1/2" NPT connector. Normal airflow range is 0.75 CFM. 1.35 lbs each. Self weighting when using normal tubing lengths
Item # PR-SAS9

These are highest-quality ceramic-type air diffusers machined from a solid block of glass-bonded silica. Because dust and dirt particles up to 30 microns in size will pass right through these diffusers, there's no need for expensive air filters. And with an air resistance of less than .25 psi, these glass-bonded diffusers are compatible with economical low-pressure blowers. They produce a uniform medium/fine bubble and are very resistant to clogging. And when cleaning does become necessary because of a buildup of calcium precipitate or bacteria, an acid bath restores them to like-new performance. Made in USA.

With their round grain pore structure, low resistance to airflow, uniform porosity and resistance to clogging, these airstone diffusers are clearly the best diffusers available for general aquaculture aeration. Smaller pores don't necessarily produce smaller bubbles. These diffusers are engineered to produce the smallest bubble possible within the constraints of a reasonable service life. In most soft water applications, they won't need to be cleaned for more than a year. Note that water pH in excess of 9.0 will shorten the diffuser life. Self-weighting when used with typical tubing lengths.

6" Airstones

Pack of four Air Diffusers, 6" L x 1.5" W, 3/8" O.D. barb (9 mm). Normal airflow range is 0.5 CFM. 0.75 lbs each. Self weighting when using normal tubing lengths
Item # PR-SAS6

These are highest-quality ceramic-type air diffusers machined from a solid block of glass-bonded silica. Because dust and dirt particles up to 30 microns in size will pass right through these diffusers, there's no need for expensive air filters. And with an air resistance of less than .25 psi, these glass-bonded diffusers are compatible with economical low-pressure blowers. They produce a uniform medium/fine bubble and are very resistant to clogging. And when cleaning does become necessary because of a buildup of calcium precipitate or bacteria, an acid bath restores them to like-new performance. Made in USA.

With their round grain pore structure, low resistance to airflow, uniform porosity and resistance to clogging, these airstone diffusers are clearly the best diffusers available for general aquaculture aeration. Smaller pores don't necessarily produce smaller bubbles. These diffusers are engineered to produce the smallest bubble possible within the constraints of a reasonable service life. In most soft water applications, they won't need to be cleaned for more than a year. Note that water pH in excess of 9.0 will shorten the diffuser life. Self-weighting when used with typical tubing lengths.

Compare Diffusers & Pricing
When comparing aeration systems it is a good idea to look for forums and reviews that
discuss the pros and cons of various systems. Since the principals of aeration
are scientific and many companies offer products that do basically the same thing
to various degrees of efficiency then it is up to us as consumers to use our due-diligence
before buying a pond aerator. To compare prices with our recommended systems we
have grouped some of the more popular bottom-diffuser aerator brands together
for comparision with our best aerator systems.

See our recommended diffusers for aeration

Below are other diffusers and systems available from other online retailers. For information on their products please contact them directly. Our diffusers are here.