Herbicides and algaecides provide quick fixes for weed and algae problems, but you should use them sparingly due to regulations and long-term risks. Biological, physical, and mechanical treatments address root causes like nutrient load. Combination treatments are effective and can help avoid repeated chemical cycles.
Summary
Should I Use Herbicide or Algaecide in My Dam or Pond?
There are lots of ways to manage weeds and algae in your dams, and one you might be wondering about is herbicide or algaecide. Do you need to use them? We want to talk to you about your options, when you shouldn’t use herbicides, and when they are appropriate.
Understanding the Options
In Australia, we have limited options when it comes to aquatic herbicides and algaecides — certainly way less than the US. They have a long list; our list is quite small. It’s not necessarily a bad thing.
It’s the other way around in Europe. I was in France recently reviewing a system there, and there is zero herbicide use allowed in France; I think Europe is generally trending in that direction.
Here in Australia, I think where we’re going, too — and again, it isn’t necessarily a bad thing. Some of the chemicals that are getting dropped in waterways around the world are scary.
I’m happy we don’t have that problem in Australia, but herbicides and algaecides are very useful in certain situations. Do you need to use them all the time? No, not necessarily; there are other treatment options — mechanical, physical, or biological.
Biological Options
Biological treatments are a practical and effective choice, but they’re more of a preventative strategy than a quick fix. It’s like a septic waste system: you’re using bacteria to clean up the stuff that’s feeding the weeds and algae.
That’s usually sludge at the bottom of the dam, but you might have nutrient runoff coming in, contributing to it, too. You don’t use biological treatments to directly kill algae or weeds. It’s there to compete with them instead. Think of products like the Biostim range, which are designed to encourage good bacteria to outcompete the weeds and algae for resources.
Mechanical and Physical Options
When it comes to algae and surface weeds, you have some simple mechanical options. You might get in there with rakes and nets, and there are special boom nets and hand-held nets like parachutes that you can pull in and clean the weeds out mechanically.
This works well for smaller areas, but there’s probably going to be a tipping point where it’s just too big a job. You can get in professional weed harvesters — there are weed harvester companies that will go in and clean out the dams, and they do a good job of that.
When it comes to submerged weeds, you can get all kinds of blankets — benthic blankets, lake bottom blankets — that are basically big weighted tarps that cover the weeds and prevent them from photosynthesising, so they die.
You can also use lake water dyes to prevent sunlight from reaching the lower levels of the water. This can be effective too. These work well in deeper water, but not as well in shallower water where the sunlight can still penetrate.
The problem with physical and manual treatments is that they’re labour-intensive, so they aren’t suited for every budget or situation. Sometimes, there are situations where chemical treatments make sense.
When Chemicals Make Sense
Sometimes, you really do need to use a herbicide or algaecide. If you want or need a quick fix, they’re going to give you one. Say you have a big event like a wedding in three days, and you need to get rid of a lot of algae — that’s when you would use an algaecide.
Still, it depends on your goals and your preferences as to whether you would choose to use algaecides or not. It’s important to understand our restrictions in Australia, too. Things like:
– Approval only for specific weeds
– Timing restrictions
– Professional application requirements
We have a limited number of options and a very strict licensing regime. It’s important to consider the long-term, especially from a regulatory point of view — some of the things we can use now may not be available in the future.
Long-Term Strategies
Whatever you do, our recommendation is that you look at the reason why weeds and algae grow in the first place. It all comes down to nutrient load. To fix it, you should look at things like this:
– Biological treatments (e.g. Biostim)
– Aeration
– Phosphorus binding products (e.g. PhosFix)
You need a broader approach. Some of these products are there to mitigate nutrient load and stop the weeds and algae from growing in the first place. That’s how we operate at Water Quality Solutions. We treat the root causes, so you only use algaecides and herbicides when we have to.
If you are going to go down the path of utilising an algaecide or a herbicide, make sure you’re buying it from a reputable company. Buy it from someone who can advise you and tell you not just what to use, but how to use it, when to use it, when not to use it, and what to expect. Arm yourself with information so that whatever you put in your water, you know you’re using the most appropriate thing to solve your problem.
Avoid Getting Stuck in Chemical Treatment Cycles
If you do use chemical products, you should use a product called Biostim Accelerator with it. Biostim Accelerator enables the chemical to be more effective on the plant, so you don’t need to use as much of it. It also rapidly degrades rotting organic vegetation, so it speeds up the degradation process too.
Once the algaecide or herbicide works, it’s a good idea to introduce Biostim Tablets or Pellets a few weeks later. These will sink down to the bottom and start degrading the organic material stuck there. If you use the Biostim products along with your herbicides, you can avoid getting stuck in chemical treatment cycles.
A chemical treatment cycle is where you treat with harsh chemicals, the problem goes away, and then it comes back… so you treat with harsh chemicals, the problem goes away, and then it comes back… again. Treat the root cause of the problem — nutrient availability — and you can avoid needing repeated chemical treatments.
Need Help With Treatment? Get in Touch
Do you need help with treatments? Get in touch with us. We can assess your site, offer FREE advice, and provide the right products and approach for your problem. Whether you want biological treatments, physical treatments, or something like aeration, we can help.
