The Importance of Being Aerated.

[wupi]

A lazy (and frugal) man's pond -

I have been trying to find a way to have a low cost but sustainable pond, and finally found one. Filtration is out because of the frequent requirement of maintenance. It turns out this can be done with less than $150.

What's the solution? Fine Bubble Pond Aeration.

Help to break down algae-forming nutrients - Decomposing bacteria is needed to break down the nutrients that cause algae growth. Namely, aerobic (oxygen breathing) bacteria. Aerobic bacteria is extremely efficient. The oxygen supplied by a fine bubble aeration system allows this bacteria to perform important tasks in the water column. One of these tasks is the essential breakdown of algae-forming nutrients, such as nitrogen and phosphorous. Without ample oxygen in the water, this rate of breakdown becomes much slower and algae begins to overtake the surface of the water. This can lead to eutrophic waters, and an overall collapse of the pond ecosystem. http://en.wikipedia.org/wiki/Water_aeration

Get rid of unpleasant pond odor - When there is not enough oxygen present in the water, aerobic bacteria become dormant. At this point, anaerobic (non-oxygen breathing) bacteria takes over. Not only is this bacteria up to 20x slower in terms of nutrient breakdown, but it also emits byproducts such as methane and hydrogen sulfide into the atmosphere. This is why you are often met with an odorous stench when walking by a stagnant pond. The mere presence of oxygen is enough to reduce this problem.

Some fine bubble aeration kits cost a fortune. I found one diffuser with base that costs less than $66, the Ceramic Dome Fine Bubble Diffuser, ABS Plastic Base. Beyond that all you need is an air pump and a tube. You can get an air pump on eBay for less than $50, plus another $30 for a self-sinking air tube. The total comes to less than $150, and doesn't require weekly maintenance.

According to Agriculture and Agri-Food Canada, "small diaphragm compressors work best for dugout aeration because they perform well at the pressure ranges (up to 15 to 20 psi) needed to aerate dugouts. An air compressor of 1/4 to 1/8 hp putting out about 1 cubic foot per minute (cfm) is sufficient to aerate a dugout up to 5 million litres (1 million gallons)." See http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=1187622591044&lang=eng

[karltinsly]

Interesting. How big is your pond? Do you have fish in it?

I've read articles similar to the one you linked to, that state that aeration serves to oxygenate and help turn the water over so that anaerobic bacteria don't all settle at the bottom, but I've never heard of aeration used as a substitute for filtration. How long have you had your new aeration setup in place?

[wupi]

My pond size is 48' x 16', 28000 gallons. I have 15 gold fish and lots of mosquito fish now, but will add some more later once I verify the aeration is adequate.

I just have the aeration set up. However, I have done quite a few Google search and found "fine bubble" aeration is all that I need, no filtration. Fine bubbles are different from coarse bubbles in that the bubbles rise slower and dissolve better. Fine bubbles aeration has much better dissolved oxygen level than other aeration methods. See video: http://youtu.be/tiyR2OYFnxg

I also looked into the venturi system, which adds air to the water during the circulation like the air jet does in a hot tub. The fine bubbles aeration method is a lot more efficient. See http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=251111. The air diffusion system is used in a lot of waste water treatment plants because of its efficiency. No odors, even for waste water treatment. See http://www.youtube.com/watch?v=lwmpWqnA9to

Here is an article that provides scientific explanation: http://www.epaeration.com/principles.php

[karltinsly]

Interesting. I haven't had a chance to read the links you posted yet, but I will. I look forward to hearing how your aeration works through the season. Your pond is very large -- I wonder if the size and volume of water might also help make filtration less necessary. Certainly plenty of plants help with converting nitrates, but bacteria are needed to convert ammonia from fish waste into nitrites and then into nitrates the plants can use. Such a large pond might be able to hold enough bacteria without needing to force the water through a bio-filter.

Please keep us posted on how the aeration works!

[wupi]

This picture shows the pond two days after the aerator was installed, quite an interesting scene. Bubbles accumulated when temperature dropped to below 50F. Before the aerator was installed I could see the gold fish swimming near the surface, probably due to lack of dissolved oxygen. One day after the installation, the gold fish were nowhere to be seen.

The bubbles are formed from many tiny bubbles (through fine bubble diffuser) joined together to form large bubbles. As they spread out, they become smaller, either due to leakage or the air being dissolved in water. The remanence of their demise are sheets of algae, which are part of a pond's ecosystem.

The primary source of oxygen for a pond is from microscopic algae (phytoplankton or drifting plants) or submerged plants. In the presence of sunlight, these produce oxygen through photosynthesis and release this oxygen into the pond water. Oxygen depletions are the most common cause of fish kills in ponds. Most oxygen deletions occur in the summer months because 1) warm water holds less dissolved oxygen than cool or cold water, and 2) because the pond’s oxygen demand is greater in warm water than in cold water. http://aquaplant.tamu.edu/faq/dissolved-oxygen/.

In a balanced ecosystem, phytoplankton provide food for a wide range of water creatures. When too many nutrients are available, phytoplankton may grow out of control and form harmful algal blooms (HABs). These blooms can produce extremely toxic compounds that have harmful effects on fish, shellfish, mammals, birds, and even people. http://oceanservice.noaa.gov/facts/phyto.html. Mechanical aeration usually can save fish during an oxygen depletion.

[jclimber99]

Wow, that sounds like a great addition to a pond!  I found the diffuser on eBay.  Can you tell me what kind of air pump you bought?  Is it like an aerator device for ponds or something simpler?  I would love to get this going and see how it works.

Thanks,
-Jason

[wupi]

You can get a "Sunleaves DuraPump Air Pump 950 GPH HYDROPONIC" from eBay for about $46. That is enough to handle a 16' x 16' pond.

My one unit has turned into 3 because my pond is 16' x 48'.

- Patrick

[jclimber99]

ok, I see that pump online.  It's rated at 950 gph or 2.1 cfm.  That is slightly higher than the 2cfm range of the diffuser.  But your diffuser is handling that input flow ok?  The next lowest rated DuraPump is 600 gph, or 1.3 cfm.

[jclimber99]

Also, was it easy to find an adapter to go from the 1/4" outlet of the pump to the 3/4" threaded inlet on the diffuser?

[wupi]

I actually have both the 600 GPH and 950 GPH, and the 950 GPH is definitely better. Buy the 950 GPH and if it's too much for you, I would be happy to trade my 600 GPH for your 950 GPH. The 600 GPH needs 1/4 inch ID hose. The 950 GPH needs 3/8 inch ID hose.

The hose and barb connectors can be found at Home Depot. If aesthetic is important to you, you might consider buying a weighted hose online.

[jclimber99]

Thanks for the info!  I think I'll just get the 600 gph model since my pond is 20'x12' and already has a pump/filter so I just need some extra aeration.  The weighted line sounds like a good idea so I'll pick up some of that too.

What did you use to keep the diffuser pointed up in your pond?  Or do you just have it laying on the bottom sideways?

[wupi]

I just have it laying sideways.

One side benefit of having an aerator at the bottom (and in the center) of the pond is the rising air bubbles push water upwards which in turn pushes floating debris to the side of the pond. It makes scooping them up so much easier.

If you do filtration, one low cost way to add air into the water is by adding a venturi system, see below, just like they do in Jacuzzi.