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Treating Algae

21st Nov 2019

lgal blooms and algae are recognised as a year in year out problem and are a real nuisance to all pond keepers. As a result of this there are numerous different treatments and a huge amount of effort has gone into remedies and methods to get rid of this perennial problem. So, we are going to have a look at a few ways of helping you guys with the dreaded Algae.

Treatments are usually best applied in spring, this is hopefully weather permitting before any large algal blooms have broken out. So why spring? Well the simple answer is that you should have minimal, if any, algae growth at this point and the treatments will work better with less algae in the water. This gives any treatment a sporting chance of getting on top of a problem. Secondly and more importantly, treating algae will result in it dying and rotting in your pond. This will cause a rise in bacteria, resulting in a large increase in oxygen consumed within your pond. This process could leave your pond in danger of oxygen depletion - so the less algae treated the less depletion of oxygen!

Often the best and safest way of removing algae is manually with a suitable implement such as a Blanketweed Brush. With blanketweed in particular this is one of the most effective remedies especially if it’s done regularly. We do appreciate this can be time consuming and a bit of a mucky job, trust us though, it will be of huge benefit to your pond in the long run. If you use a reatment, and leave all the nutrients to be left to rot - these can be used by different strains of algae to help them grow in the future, which isn’t ideal.

I have lost count of the many treatments we have stocked over the years here at Bradshaws, we have certainly tested our fair share of them that’s for certain! Most of them work pretty well, however they do have their limitations as to which algae they will treat or when they work most effectively. Personally, I think this can be very confusing, you will use a treatment and it will work amazingly well, then the next time you use it, somehow it doesn’t work at all! All sorts of things like water temperature, time of year, not using the correct dosage can influence how well algae treatments work, so this is why it can be difficult for us to give the answer as to the ‘best’ treatment.

Organic Treatment

It’s probably easier to explain how treatments work, starting with the organic treatments such as Barley Straw and the Extract of Barley Straw that have been popular remedies for years. It isn’t 100% understood why Barley Straw works, people think that when it breaks down the chemicals released inhibit the growth of Algae. It has certainly stood the test of time though as it has been used since around the mid 90s as an algae cure. This treatment is best used as a preventative measure in ponds that are expected to suffer from algal blooms - it seems a lot of people on farms use this as they have easy access to barley straw. It needs to be placed in a pond weeks before the algae starts to grow, giving the barley straw time to break down.

Recent treatments new to the market use a technique where they release bacteria into the water. These quickly use up nutrients such as Phosphorous and Nitrogen, leaving less available for the algae - therefore starving it out. Examples of these that we sell are Blanket Answer by Cloverleaf, Nishikoi Goodbye Blanketweed and our own radshaws Blanketweed Pouches.


The most obvious and well known treatment method is a UV Clarifier which is used as part of a filtration system. These work by killing and clumping individual algae cells together so that they can then be mechanically filtered out of the water. UVC’s have long become part of an established filter system, they do have the benefit of also killing some of the free-swimming stages of parasitic organisms in the pond as well.

The other less used type of electrical remedy is the T-Tronic. This introduces copper ions into the pond water, in safe levels copper prevents the growth of Algae in a pond. It uses the same type of technology that stops bottled water from going green on supermarket shelves.

Shade Sale - Image


A very simple way of controlling algae growth is using shade, this reduces the amount of sunlight that can get to the pond. Why is that important? Well it stops energy getting to the algae which is its primary source of growth. So, you could put up a pergola, gazebo or anything that will stop so much sunlight getting to your pond. Another method would be to use a pond dye, these have crept onto the market in the last few years, they work by reducing the amount of sunlight that is able to get to the pond. Some available treatments use this as part of their process, including Cloverleaf Blanket Answer, Algofin, Algorem and Nisihikoi Clearwaters. You will notice the pond water change colour slightly when you use these treatments.

Algae prevention Essentials

  • Shade – Through plants or a sun shade
  • Pond Pump – A quality pond pump helps keep a good steady water flow
  • Filter and UV – A good quality filtration system to remove Nitrogen compounds and algae
  • Aeration – An oxygenator will provide essential oxygen to your pond
  • Plants – If possible use plants, they compete with algae and look great!