How can I get rid of Blanket weed in my pond?
Blanket weed, string Algae, whatever you want to call it, it’s a nightmare! It looks horrible, it traps debris and bacteria and can be lethal to fish like Sturgeon.
Many people aren’t affected by it at all, others have perfectly healthy ponds for years and then suddenly develop it. This can often be a random occurrence or something simple like a bird or other animal bringing a few cells into your pond, and that’s all it takes.
For that very same reason, emptying your pond and jet washing it to within an inch of its life, is not going to solve the problem. Only a few cells of this pest algae need to survive and it will be back to full strength in no time at all!
You could say that Ultraviolet sterilisers are to blame for this problem (hear me out on this one!) UV’s are known to kill any algae that pass through them. Blanket weed is more often than not stuck firmly to the side of your pond, so rarely travels through your UV.
Before the invention of UVs you either had a perfect balance in your pond and clear water or you didn’t.
UV’s gave us a way of achieving crystal clear water without addressing the levels of nutrients in the pond that causes algae. So effectively blanket weed has found an environment with an excess of nutrients and no other pesky single-celled algae blocking out all the sunlight. Perfect conditions to grow and thrive. Just to make matters worse, there are also levels of nitrates and phosphates in tap water, so every time you do a water change you could be feeding the algae.
Trying to get rid of blanket weed can often be difficult, removing it manually is a thankless task as it will grow back rapidly. You have to tackle it head-on by either putting a treatment in to kill it or treatment to starve it. All blanket weed treatments will work by using one of these two methods. Killing it tends to be quicker but the resulting dead algae can often end up rotting creating more nutrients for the blanket weed or other algaes to thrive once more. The starving route tends to work far more slowly but as the nutrients have already been dealt with there is no chance of the algae reoccurring.
Pond blanket weed
Pond blanket weed
There are more blanket weed treatments on the market than you can shake a stick at these days!
Unfortunately, some work best in certain ponds than others, which is why there are a lot of conflicting opinions as to which is the best treatment:
– Barley straw
Barley straw can be added to ponds and has been proven to reduce algae problems in a wide range of pond sizes. It is also a cheap option and simple to administer.
However, it is completely dependent on water temperature so can take up to 6 weeks to work in colder waters. The process is completely reliant on the breakdown of the barley straw by bacteria and then fungus (you have something rotting in your pond!). If overdosed it can cause fish deaths as the process sucks the oxygen out of the water. Because of this most manufacturers are extremely conservative when giving dosage rates for barley straw, so the process may take much longer than expected.
There are also barley straw extracts available which bypass the rotting plant matter phase and go straight to the active ingredient. This is still not the most effective blanket weed treatment but is often a cleaner alternative to barley straw.
– Cloverleaf Blanket Answer
This is probably the most popular blanket weed treatment on the market today and you can find it here.
We have tried numerous treatments over the years, this seems to give consistently good results and the feedback from customers is almost always positive. It starts work very quickly but works best when the water temperature is above 10 degrees.
The manufacturers recommend maintaining good levels of oxygenation especially when you have fish such as Rudd and Orfe in your pond. They also suggest a half dose followed by the remainder a few days later when such fish are present. If you have tadpoles or frogspawn in your pond then splitting the full dose into 4 and treating every few days.
It does send your pond milky for up to seven days, and because it works so quickly the dead algae can then become a problem in the pond so you would then turn to something like Sludge Answer.
Cloverleaf Blanket Answer will often require repeat treatments throughout the year and can become costly on larger bodies of water, but it does work, and if you have suffered from this problem for some time it’s an amazing product to give you fast results.
– Ecotreat Clarity – a more natural approach?
Rather than looking to kill the blanket weed outright, Ecotreat Clarity has taken the approach to starve it instead.
This is far from the quickest method of getting rid of blanket weed and if you are after a quick fix then Cloverleaf Blanket Answer as mentioned above is often a good choice. We do, however, suggest treating with Clarity in the background. It works by outcompeting all forms of algae for sources of nitrogen and phosphorus, by adding beneficial bacteria that get to work on digesting rubbish in the pond.
It is, in essence, a pond conditioner that has the added advantage of preventing algae from growing. You would generally need to wait for 4 weeks before seeing results, but by adding a small amount every week it keeps the pond in exceptional condition and aims to restore this perfect balance I talked about at the very beginning of this article (back when you were still wide awake!). Ecotreat clarity is also very economical. A £7.99 250g tub will treat a small pond (less than 2500 litres) for up to 6 months. It is also incredibly economical on larger ponds and lakes with Ecotreat Clarity pro 3kg treating up to 525,000 litres for 6 months.
Because Ecotreat Clarity and clarity pro, are adding bacteria to your pond to digest sludge and waste, the added bonus is that your filter maintenance will be less. sludge is sludge, whether it’s in your pond or your filter. The reduction in algae also leads to a much cleaner pond. By preventing its growth in the first place your filter is having to concentrate less on dealing with dead algae produced by your UV and the breakdown of old blanket weed.
In short (maybe I should have started with this!) there is not one perfect treatment for blanket weed, they all have their merits and failings. Ecotreat Clarity does come out very well as it is one of the only products not adding to the bioload in your pond or rapidly reducing oxygen levels, but it does take some time to work. Cloverleaf Blanket Answer works very well, very quickly but there may be some cleaning up to do afterward. Barley straw can work, but getting the right amount can be a little tricky. There are also electronic methods (maybe for another article!) which tend to be better suited to koi ponds. These are effective but need monitoring carefully and can be expensive to set up initially. It can all boil down to your patience and the severity of the problem.
More often than not, we recommend a combination of products to solve the problem for good! I know that probably sounds like a sales pitch, but it isn’t and if there was a “wash and go” 2 in 1 option for blanketweed, believe me, we would be singing about it from the rooftops!
We would recommend blitzing the blanket weed with Cloverleaf (you may need to administer 2 doses over the next 6 weeks) and treating with Ecotreat Clarity in the background. This combination gives you the best of both worlds, quickly killing the blanket weed, and then laying the foundations so that the blanket weed never comes back again!
You can buy this recommended Product Combo here!
Martin Litt 17.03.21
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