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How Would I Know If My Pond Has Sufficient Aeration? – Pond & Lake Q & A


Comparing No Aeration, Under Aerating & Sufficient Aeration

Q: How would I know if my pond has sufficient aeration? What would happen if my pond was “under” aerated?
- Joe of Michigan

A: The best way to test to see if your pond is sufficiently aerated is by taking the temperature of the water one foot below the pond’s surface as well as the bottom. If there is a difference of more than 3 degrees Fahrenheit, then the pond is not sufficiently aerated and you may need to add additional diffusers or relocate the diffuser that you have.

Next, to answer the, “What would happen if my pond was “under” aerated?” question, lets compare a pond with no aeration, a pond that is under aerated and a pond with sufficient aeration.

A Pond with No Aeration: With no aeration present, the water is stratified (aka has a thermocline). Meaning that the water at the top is warmer and full of oxygen while on the bottom the water is cooler, nutrient rich and contains no oxygen. This causes the fish to habitat towards the surface of the pond. As the seasons change from the hot summer to cold winter, the pond goes through a process known as “turnover”. This is when the cooler water at the bottom of the pond, mixes with the warmer water at the pond’s surface. Since the rising cooler water contains no oxygen, the chances of a fish kill are imminent.

A Pond that is Under Aerated: When a pond is under aerated, the thermocline is not eliminated, only dropped further down towards the pond’s bottom. This can cause constant problems. As the bottom bubbler aerates, the bottom, nutrient rich water is lifted to the pond’s surface. These nutrients are now constantly available for algae to grow. More importantly, the water that is being lifted by the bubbler also contains no oxygen, thus increasing the possibility of creating turnover and killing the fish.

A Pond with Sufficient Aeration: You may ask, “Since the nutrients are still being brought to the surface, won’t an algae bloom and turnover still happen even if a pond is properly aerated?”

When an Aeration System is initially installed, it should be started at a slow pace to prevent creating turnover (See blog “When & How to Start Your Aeration System” for more information). As for algae, initially, when the nutrients are pushed towards the surface, algae will have the chance to bloom. As time progresses, however, the thermocline will be eliminated, the nutrients will be flushed out and the fish may now habitat the whole body of water.

13 Responses

  1. I have a 3/4 acre pond with bass and bluegill. I’m not sure how old the pond is but I’ve lived there for seven years. It’s never been aerated and is fed by a spring and run off waters. I’ve never had any fish kill but have had some pretty bad weed problems and thick muck in the past few years. My question is, when I place an aerater in I’m guessing it’s going to stir up a lot of the bottom muck, will this hurt the quality of water? I want to start fixing the problem but don’t know where to start.

    • Charlie,

      That is a great question. When you first start up your aerator, we recommend to start it up slowly, because your right, at first you will begin to bring up some of the muck and debris, which is a good thing. In order for help further break down these bottom muck and organics, oxygen has to be present.

      Bottom line, at the beginning the water quality may become murky depending on how much muck is on the bottom, but it really won’t take long after for those debris to settle and for you to be on the way to a more healthier pond.

      Hope this helps answer your question. Thanks for the comment!

  2. Hugo,

    Raking around the pond’s edge with a Pond & Beach Rake is a great way to remove a lot of excess bottom muck, weeds and algae relatively quickly.

    Adding PondClear Natural Bacteria is a great way to break down suspended organics within the water column. This will help clear up your pond.

    Adding Nature’s Blue Pond Dye with add an aesthetic blue shade to your pond and help combat any ugly looking water.

    Adding an Airmax Aeration System has always been one of the best ways to keep your pond in tip-top shape all year long.

    I would start with raking the pond first and then proceed to the next steps that I talked about above. This should help you get off to a great start quickly.

    Hope that helps!

  3. Hello –

    We have a one-acre shallow pond approx 8-10 ft deep at the deepest. It is fed by rain and runoff and therefore does not circulate very well. There are no fish, but we get frogs, crayfish, etc. What is our best option to get the pond clean, warm and swimmable as quickly as possible – our summer is very short!

    Thank you!

  4. Tim,

    Do you have an aeration system? Also, how deep is your pond? What is the length and width of the pond? I definitely want to help you out so let me know as soon as you can.

    Thanks.

    • I HAVE 700 GALLON POND IN WHICH I HAVE 12 GOLDFISH AND 1 KOI MY KOI IS 13 INCH LONG I HAVE NOTICE THAT MY KOI IS STAYIN IN 1 SPOT DURING THE NIGHT AND SOMETIMES HIDING HIS FACE INBETWEEN ROCKS? COULD IT BE OXGEYN I HAVE A WATERFALL AND AN AIR STONE. MY PH LEVEL WAS 7.5 AND SOMEONE TOLD ME THAT WAS TO HIGH SO I BOUGHT SOME PH DOWN. IT IS MID JUNE IN NY JUST SEEMS STRANGE THAT ALL OF A SUDDEN HES NOT AS ACTIVE AT NIGHT HE EATS AND SWIMS DURING THE DAY.

  5. have winter kill from snow and ice even grass carp are dead, beleive all fish are dead appox. 1/4 acre pond. please help where do i start

  6. Jack,

    You are still in a good position because your pond is still young compared to most. Being proactive like you are will make things easier at your pond enters its second stage of life (after 5 years). As long as you are doing the 4-steps, you should be fine. Over the next year or so, you may see some additional algae blooms develop but just spot treat with an algaecide and you should be all set.

  7. Thomas,

    There are two factors you have to consider when adding an aerator to your pond: Circulation & Aeration.

    Circulation: Circulation is ensuring that the whole body of water is continuously moving and allows the temperature throughout the pond to be relatively the same (eliminating the therocline). The aerator must be continuously running 24 hours/day in order for this to happen. Usually this can be take up to 72 hours of continuous aeration before the whole body of water is circulating.

    Aeration: The windmill is adding some aeration, but if it is not continuous, it unfortunately is not being saturated throughout the entire pond. Windmills are great if there are no other options available because they are definitely better than nothing at all, but an electric aeration system is still way more efficient at pumping that air into the water as well as circulating it.

    Remember that an electric aeration system can sit as far as 1,000 from the pond’s edge. That’s almost 1/5 mile away!

    Testing for Oxygen: You can test for oxygen, using an oxygen test kit. It is very important to test different spots throughout the body of water. In a large body of water such as yours, the oxygen readings will differ in the different spots. In your case, since the windmill aerator is not continuously running, the oxygen levels towards the bottom of your pond are much lower than those at the surface.

    Let me know if you need anything else!

  8. Peggy,

    Many customers that have a 140 gallon water garden will shut it down throughout the winter time. Usually by draining and cleaning the pond, bringing the fish indoors into a tank, and removing the pump for storage. Peggy, do you plan to run your system throughout the winter time? Do you have fish now?

  9. I have had a 1/4 pond for 3 years. This is the first year I had Aeration. I there any thing else I should be doing. I am under your 4 step program now. I do notice that my bottom is some what slimmy. It a clay based pond. No fish.

  10. I have installed the wind powered aerator from your catalog.
    The fan doesn’t turn unless the wind is about 4-5 mph, so there is a lot of down time. How can I be sure I’m putting enough air into the pond?

  11. what do i do to get my pond ready for winter? im in chicago and have a 140 gal pond with waterfall.

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