Natural Ways to Control Algae

Herbicides and algaecides have their place, but natural control methods are a much more effective long-term solution for common water quality problems.

That’s why we want to talk to you about algae, why it happens, and the natural control methods you can use to fix it.

Algae: Why It Matters

We get clients all the time who call us up to talk about algae problems — they have too much algae, they want to kill their algae, they don’t know why it keeps coming back. The thing is, algae is typically a symptom, not the problem.

The problem is usually too many nutrients in the water, which feed the algae in the first place. Your water can become unbalanced: there are so many nutrients in the water that the weeds and algae feast, and their populations explode, and suddenly you’re dealing with a massive algal bloom.

You can reach for chemical treatments, but they only treat the symptoms. You kill off the algae, but because the basic cause is still there, it’ll just grow back. So when we’re talking about naturally controlling algae, we have to go to the root of the problem — we want to prevent it from growing in the first place by controlling the nutrient load. 

Step 1: Find Where Nutrients Are Coming From

One of the first things you need to do is look at where these nutrients are coming from. Basically, any kind of organic matter that falls into your water is part of this problem, so you need to take a wide look at it. Typically, what happens is that anything organic, like leaf litter, bird waste, or fertiliser, falls down to the bottom, and that becomes a nutrient sink.

Do you have runoff coming in from paddocks high in fertiliser or animal poo? Do you have reclaimed water coming in from the local treatment plant? Do you have water coming in from a neighbouring property that you have no control over? Do you have a lot of leaf litter or plant debris? Do you have a lot of ducks that visit your pond?

The first step is figuring out exactly why you have an excess of nutrients. All these things are common sources. Take birds — if you’ve got lots of ducks, they’re going to be pooping. A duck poops about every 15 minutes, so they’re a big polluter of dams. That’s a lot of extra nitrogen and phosphorus.

Step 2: Fixing the Nutrient Sink

After you’ve figured out where the nutrients are coming from, you need to look at what you can do to try to mitigate them. Depending on the source of your excess nutirent, you can do a lot of different things.

If you have a drain or a gully that the water’s coming in from, you can look at planting that out to try and use plants to soak up some of the nutrients before they come in. You might look at riparian planting — planting around the outside of the dam — so that any water that’s coming in has to cross through the plant life.

The basic idea is that you figure out exactly where your excess is coming from and take steps to prevent or reduce it. For example, if you know you’ve got nutrient-rich water coming in, you can try diverting it through other areas if you’ve got the luxury of multiple water sources. If you have an excess of birds, you can try encouraging the birds to live elsewhere.

It’s about finding practical ways to cut off nutrient supply. But that’s only half the battle, because you need to deal with the stuff that’s already in your dam, too.

Step 3: Deal with Sludge

The problem with runoff and excess nutrients in your water is that they stick around. Over time, the organic matter that falls into your water becomes a thick sludge at the bottom and acts like a compost fertiliser for algae and weeds that live above. This thick layer becomes the main source of nutrients for algae to grow.

Dealing with the sludge is a key part of the process. Think of what we do here like a septic system — you’re using bacteria to clean up the waste. In dams, the bacteria we need are the aerobic bacteria. They do the best job, and that’s also part of why we aerate dams: aerobic bacteria love oxygen.

Putting an aerator in makes a big difference because you need the oxygen to get right down to the bottom of the lake. Working with a reputable company that understands aeration can ensure you don’t end up buying a decorative fountain that won’t help.

Another part of the solution for sludge is products like the Biostim range. These help you stimulate bacteria in the sludge layer and help them to thrive. This ramps up the number of good bacteria in your water and speeds the degradation process up.

Step 4: Fix the Phosphorus

We use a phosphorus-binding product to help control phosphorus in the water. It’s called PhosFix, and it’s a blend of minerals and bacteria that specifically targets phosphorus to take it out of the water column. 

It sinks down to the bottom and, if you do a sediment dose, it will penetrate the sediment and lock up phosphorus that’s been building up in the nutrient sink at the water bottom.

This is fantastic because in freshwater systems, phosphorus is the main limiting factor in algal growth. When you get more phosphorus, you get massive algal blooms. If you can reduce the phosphorus in your water, the algae is going to hate it — it’s going to have very little food, so it’s not going to grow in the first place.

Step 5: Natural Algae Removal

Those approaches covered natural methods or control or prevention, but once it’s already in the system, you’re looking at mechanical solutions. If there are blooms of filamentous algae you can pick up, you might need to rake it out and pull it to try and remove it. That’s quite labour-intensive, but it does work.

You can try things like dye to shade algae out. It’s not necessarily natural, but it’s not a harsh chemical method either. It’s equivalent to food dyes. What you do with this method is you starve them of sunlight — it won’t go through the dye — so you reduce their growth and they die off.

Barley Straw — Worth It or Not?

Barley straw is a solution that kicks around the Internet quite commonly, but in my 20+ years in the industry, I’ve only seen it be effective and easy to use in much, much smaller water bodies. The process works by releasing a mild form of hydrogen peroxide as it rots in the water. The problem with barley straw — and why I don’t like using it — is that for it to be effective in anything other than a very small dam, you’re going to have to use a lot of barley bales. 

When you do that, it’s a balancing act between getting to the point where it rots and exhausts all its benefits… and then you have to be able to physically remove it from the dam. If you don’t, and it gets so waterlogged it’s heavy to move, you have a problem. What happens then is that you’ve got depleted, rotten straw at the bottom of the dam, and it’s actually become a contributor to the problem because it’s now feeding the algae.

There are, nowadays, some liquid extracts available that could maybe work in the pond industry, your backyard, you know, bathtub-size fish ponds. In something like a dam or even a larger pond, the benefit that you’re going to get for the cost of trying to put it out there is negligible. 

Algae Lift

Algae Lift is a product I wouldn’t go so far as to call natural, but it’s bordering on natural. It’s a rock and waterfall cleaning product that we use, and we use it when we need to clean biofilm and debris from rocks. 

It’s hydrogen peroxide-based, so it breaks down into hydrogen, oxygen, and water. It’s a less harsh product than chemical treatments, but it works better than barley straw.

It works well, but you are putting a lot more hydrogen peroxide into the water than with barley straw.

The Key Message

Controlling algae isn’t about choosing a particular herbicide or miracle treatment. It’s about addressing the root causes of algae:

– Excess nutrients from runoff and waste

– Nutrient-rich sludge

– Excess phosphorus

– Poor aeration and poor aerobic bacterial activity

If you get the root causes under control, you won’t need to use repeated chemical treatments that just don’t seem to work.

Ready to Get Started?

If you’re ready to get started with natural control methods — Biostim, mechanical removal, aeration — get in touch with us. We can assess your site, offer FREE advice, and supply you with effective solutions and products to help you bring your water back to life the natural way.