Surface aerators boost oxygen in dams, improving water quality by supporting aerobic bacteria and reducing sludge, odours, weeds, and algae. They work well in small to medium dams around 4 to 5 metres deep and offer strong oxygen transfer.
Summary
Surface Aeration 101—Oxygenation via “Ripple Effect” and Surface Agitation
If you manage a dam, lake, or large pond, aeration is one of the best things you can add to your toolkit. We see lots of problems with dams or water bodies, and poor aeration is one of the biggest causes.
That’s why we want to talk to you about why dams need aeration and why surface aerators are a great choice.
Why Dams Need Aeration
The reason we want to aerate dams is that the more oxygen you can get into the water, the more aerobic bacteria you can get into the water. Aerobic bacteria is the “good” bacteria your dam needs — it quickly digests the stuff that’s on the bottom. After years and even decades of leaf litter, fish waste, duck waste, all kinds of organic material, ending up on the bottom, it becomes a thick kind of sludge — and a fertiliser for algae and weeds.
In dams that aren’t aerated, you end up with anaerobic conditions on the bottom with little or no oxygen. And in those conditions, anaerobic bacteria populate, and they clean that waste up but they do it really slowly and produce byproducts like methane and hydrogen. Over time, in man-made dams, you see this kind of process happen often. It’s called stratification, and it separates the water into thermal layers and creates an oxygen and temperature gradient where the heat and oxygen are at the top of the water instead of being distributed throughout.
Adding aeration to the dam will naturally increase the numbers of aerobic bacteria, quickly get rid of odours, and start chipping away at that sludge layer on the bottom. Over time, the algae and weeds are outcompeted for the available nutrients, and they become less of a problem.
Where Surface Aerators Work Best
Surface aerators are very intensive, so they’ll put a lot of oxygen in the water really quickly. If you’ve got a small dam and an appropriately sized surface aerator, you can turn it on and off at certain times of the day, and that’s enough to do the job.
In large, deep dams, you might combine it with a sub-surface system as well. Then, you put a surface aerator near a foot valve. That helps reduce the amount of biofilm and biofouling in the equipment, because a lot of those organisms that grow on the inside of pipes thrive in anaerobic conditions.
Surface aerators are good from an aesthetic point of view; you can have the aerating fountains that throw water up into the air and look somewhat ornamental. Perfect for golf courses or special events where you want something impressive. For some wastewater applications, you can get special aerators that oxygenate the water and really circulate the water around to distribute the bacteria well enough that they can work.
They’re especially good for fish farms because you get a lot of oxygen into the water very quickly — so you can stock higher numbers of fish.
Surface aerators are fantastic choices in:
– Small to medium-sized dams
– Waterbodies less that 5m deep
– Golf course lakes
– Aquaculture setups
– Ornamental or feature ponds
– Certain wastewater applications
Decorative Fountains vs Surface Aerators
Decorative fountains are visually appealing. They look great and they make fantastic statements for events or special occasions… but they don’t aerate. If you do go with a fountain, make sure it runs with a propeller — anything else just won’t aerate your dam. You need a propeller-driven aerator, not a decorative fountain.
Think of it like putting a pool pump next to a boat motor, even if they’re both the same size. The boat motor is going to move a hell of a lot more water for the same amount of power. Propeller-driven aerators just move more water.
How Surface Aerators Work to Improve Water Quality
Surface aerators throw water up into the air. It slightly cools, and then it hits the water, and it’s a little denser. It goes deeper into the water and circulates down, only for the cycle to repeat. Surface aerators are good for up to about four to five metres deep.
Once you start getting into deeper water, they don’t work as well — that’s when you look at a sub-surface or a combination of surface and sub-surface aeration.
Surface aerators also produce a “ripple effect”: when the fountain hits the water, it creates lots of ripples that provide a much larger surface area for gas exchange. That means the amount of nasty gases passed from the bottom of the dam increases, resulting in more oxygen transfer when compared with flat water.
Positioning a Surface Aerator
The position of your surface area matters. You need to think about where it’s going so that it isn’t blocked by an island or it’s not too close to a bank; you want it to distribute water well.
Surface Aerator Pros & Cons
Pros
– Fish — if you have a fish dam, surface aerators are good for supporting the fish. During emergencies with oxygen levels, fish will congregate near the aerator, so it’s a good way of visually seeing a problem, and it also helps sustain the fish.
– Very high oxygen transfer — they’re effective aerators when you need to improve water quality fast.
– Can be ornamental — they make suitable features when you need one.
Cons
– Swimming dams: When placing a surface aerator in a swimming dam, there’s going to be power in the water. So if you do use one, you would want to make sure you turn the aerator off every time you go into the water. But while you can do it this way, we would recommend using a sub-surface system instead.
– Power consumption: Surface aerators take more power than a subsurface aeration system. You also need power at the water’s edge, or you need to use a solar system.
– Better for shallower dams: If you have a very deep dam, surface aerators won’t do much good. You’d need a sub-surface system, or the two systems working together.
Ready to Aerate?
If you’re looking to get started with aeration, contact us. We can assess your site and help you find the right aerator for your needs. All advice is FREE and no-obligation.
