murky water

How to Clear Murky Water in Dams

Follow the below steps for the greatest chance of removing murkiness from your dam water

What is murky water?

We use the following terms to refer to different types of turbid or discoloured water: murky/cloudy, muddy and stained. Murky/cloudy water is caused by suspended organic debris, e.g. decaying plant matter, animal excrement, insects, microorganisms etc. Muddy refers to water that is discoloured or muddied from a high level of suspended inorganic content, e.g. dirt, soil. Stained water looks like black tea. This tannin colouration is typically caused by a high amount of leaves entering the water whose colour is absorbed as they decay.

Is your water muddy, murky or stained?

The first step is to make sure you are actually dealing with murky or cloudy water (from organic content) not muddy water (from inorganic content). 

Typically you can spot muddy water from a mile away. You can’t see into it at all—it looks like a sheet of brown or greyish brown. Although you may see fine particles up close, the colour and texture of the water should appear the same everywhere. When you do look closely you shouldn’t see particles clumped together in areas. Instead, you’ll see a homogeneous substrate of fine sand/soil. If your water is muddy, go here.

Murky (or cloudy) water isn’t the same colour or tone throughout. The water is generally clear but you can see some particles in it. Some areas are likely to appear cloudier than others, and if you look closely you can often see organic material (e.g. micro-organisms, leaves, algae, excrement) rather than fine dirt particles. Some areas might also have a green, blue or olive tinge (this is the organic matter). If your water is murky, jump to the next step.

Stained water looks like weak tea. The water is often crystal clear but discoloured by the tannins that come from leaf debris. You can learn more about tannins in dams here but the short answer is unfortunately there isn’t anything you can do to remove the colour from the water unless you remove the surrounding trees which are responsible for shedding leaves. This isn’t advisable as it can disrupt the ecosystem in a big way. Our advice would be to recognise tannins aren’t a bad thing and get used to the colour.

How to treat murky water

As explained above, murky water is ‘murky’ because of excessive organic material suspended in the water, both living and dead. So we need something to clean up this material. This is where “good” aerobic bacteria come in. These microbes eat the dead/decaying suspended organic material which clears the water somewhat. The “good” bacteria also consume nutrients (e.g. nitrogen, phosphorus) which invasive pests depend on to survive. In other words, the bacteria start to chip away at populations of algae, aquatic weed and invasive microbes. This too brings down the amount of suspended organic material, ultimately leading to clearer water.

So, how do we ramp up populations of “good” bacteria?

Step 1

Increase aeration

Aeration means adding oxygen to your water. This provides ideal conditions for “good” aerobic bacteria to grow in number. These “good” guys get to work reducing murkiness in your water in a number of ways. (i) They directly consume suspended decaying organics, which improves water clarity. (ii) Through their own metabolic processes, “good” bacteria also reduce nutrients in your water, such as nitrogen and phosphorus, which reduces how much food there is available for aquatic pests, e.g. algae, aquatic weeds, “bad” microbes etc. As these invasive populations plummet—through being outcompeted—your water will get clearer. (iii) “Good” bacteria also eat the sludge on the floor of your dam, which again reduces how much organic content there is in your waterbody. Sludge is fertliser for invasive pests, so tackling it also reduces how much algae or weed there is in your water.

surface

Surface aeration

Surface aerators sit on the surface of the water and use a propeller to pump water up into the air. This allows for gas exchange between the water and the air where oxygen enters the water before it returns to the waterbody. Agitating the surface of the water also creates a ripple effect which increases the surface area of the waterbody. More surface area means more gas exchange, resulting in greater aeration.

Shallow water

90%

Deep water

30%

Speed to aerate

85%

Power consumption

70%

Suitability for swimming

20%
sub-surface

Sub-Surface aeration

Sub-surface aerators involve using air-stations (often multiple) set up on the floor of your dam. These systems pump out air which becomes bubbles. These bubbles rise to the surface, getting larger and larger as they climb. This drags less-oxygenated bottom-waters to the surface where oxygen can enter the water. When the water becomes more oxygenated, it gets heavier and sinks, producing a circulating system.

Shallow water

30%

Deep water

90%

Speed to aerate

50%

Power consumption

40%

Suitability for swimming

89%

How does aeration improve water quality

Step 2

Add Biostim probiotics

Biostim is a probiotic that feeds the “good” bacteria in your dam, growing their populations. As mentioned above, these guys clear your water of organic cloudiness, consume nutrients algae and weeds depend on to survive and eat the sludge on the floor of your dam. This all amounts to clearer water from the surface to the floor. We recommend Biostim Liquid of Biostim Powder for treating murky water as these Biostim products target the entire water column. If you don't have much sludge, Biostim Liquid is the better option. If you have sludge and murky water, we recommend Biostim Powder.

How does Biostim improve water quality?

Biostim Powder treats both the water column and floor, making it ideal for clearing organic murkiness from your water and treating small amounts of sludge. Dropped into your dam in water-soluble bags, the powder saturates the water column before the last of it settles on the dam floor.

Biostim Liquid is ideal for new dams to spike the water and for dams with high amounts of suspended debris, i.e. murky-looking water, but little to no sludge. It is the fastest acting probiotic in the Biostim range. The solution spreads quickly through your entire water column and wakes the microbes up.

Biostim Pellets and Tablets are primarily used for reducing sludge. The products are essentially the same thing, the tablets are just slightly more potent. The pellets/tablets sink to the dam floor and settle in the sludge, dissolving over weeks. This provides life-sustaining resources to populations of “good” microbes so they can eat away at the sludge.

Biostim Accelerator is a biocatalyst that speeds up the degradation of dead and rotting weed and algae, making it an ideal companion with algaecide or herbicide use. Without it, dead rotting material can remain floating in your water for weeks and will often end up on the floor of your dam becoming fertiliser for next season's algae/weed. 

Biostim Booster Blocks are highly concentrated probiotic blocks that can be used in wastewater and areas of super-concentrated nutrient levels. The block is tied to an object where the water is moving fast, e.g. an aerator or at the base of a waterfall. The blocks can last up to 60 days depending on the flow rate.

Biostim Powder

Biostim Liquid

Biostim Accelerator

Biostim Pellets

Biostim Tablets

Biostim Booster Block

expert Advice

Need help? I'm Scotty Tucker and I offer FREE advice

I'm happy to take a look at your dam [on Google Maps] and provide FREE advice on the right type of aerator, motor size and placement. I can also answer any questions you have on improving water quality.

"Since WQS installed the aerator, we've not had a single algae problem. In our smaller ponds that are too small for aerators we used Biostim pellets on their own and have noticed a huge reduction in algae.”

Andy Hart

Horticultural Curator—Department of Environment, Water and Natural Resources, Adelaide

“We had a nutrient-rich stormwater lake that was having continuous problems with algae. We were previously treating the nutrients with a liquid solution that would just end up getting flushed away with the outgoing water. Scott recommended we switch to Biostim pellets which were exactly what we needed.”

Giles Pickard

Environment Project Officer, City of Subiaco

“Visiting ducks and our pet geese were continuously fouling the dam. WQS recommended a number of systems to improve the water quality. We are very happy with our final choice, the windmill aeration system. This combined with the Biostim pellets and liquid are cleaning up the dirty dam. Everything WQS said would happen has happened!”

Greg Lewis

Canterbury, Victoria

“We had an urgent problem—our old irrigation system had blockages from weeds. Our dam was also riddled with black sludge. Scott recommended both aeration and biologicals and within six weeks the dam became so clear I could see to the bottom of it for the first time in years! I was chuffed that we could fix the issue without the use of chemicals.”

Michael Grant

Owner, Grant’s Citrus Farm
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