In my continuing effort to share some common questions that we get here at Pond Algae Control Central I wanted to address a few surrounding Green Clean algaecide.
Way back in 2004 or 2005 I became aware of, what at that time, was a revolutionary non-copper based algaecide that could be used to topically treat algae blooms. Since that time, a number of other granulated peroxide based treatments have come along, and most are quite similar in their formulation. Some are registered with the EPA as an algaecide and some manufacturers haven’t taken that step but for the most part, other than the concentration of peroxide, they are all similar in how they work.
Peroxide is commonly used to disinfect cuts and scrapes as you probably know. When applied to a wound it will fizz and bubble a little and a similar thing can happen when contacting an algae cell. This reaction breaks down into oxygen and water so the byproducts of the treatment are quite organic. Handling the granules should be done with care however because when they do get wet they can become a bit caustic and for a short time they can burn those things they come in contact with. So ideally you want to apply Green Clean away from desired plants and keep fish in mind too. Generally they won’t get hurt by the stuff but a bit of precaution can be helpful. I always suggest folks make sure to not leave unattended granules around that don’t get dissovled too. You don’t want a bird, bee, or pet picking one up so simply make sure they all get wet or in the water and they’ll dissolve down to the harmless substances.
This “byproduct” is what makes the peroxide treatments so desirable. There’s no residue of copper or other chemicals and many people find favor with this for eco-friendly reasons.
There is a trade-off though in this short term effectiveness.
We suggest using Green Clean and other peroxide products on string algae spots, waterfall rocks, stream beds, and other hard to maintain locations. How often it may need to be applied will vary from pond to pond, but once a week to every few weeks is common. Normally for pond wide, heavy algae reduction we don’t use it (and great care should always be taken when treating large blooms that cover most of the pond). You may recall, since we talk about this often, but when you kill too much algae off too quickly, it will pull a lot of oxygen from the water and you want to avoid that if possible.
In addition, we don’t use it on green water algae at all.
Keep in mind that green water is actually a large number of single cell algae that are floating around. With the spot treating capability of the granules it’s fine on a well defined growth of string algae, but on single cells, it’s simply too difficult to really target it well. Nevertheless, with a shot of Green Clean you may see the green water clear a bit, but once the treatment wears off (usually less than 15 minutes), the algae will begin to grow back again. and single cell can grow quite quickly.
So, since green water is hard to target, and returns quickly it’s just not well suited to be treated with peroxide formulas. The overall costs far outweigh the benefits of this particular type of algae control in my humble opinion.
Green Water Treatments That Work
There’s no hard and fast rule on what you could try first here to clear up green water. The simplest and cheapest option might be to do some partial water changes. Something like 25 to 30 percent exchange over a period of days or weeks may help to reduce the green tinting.
Algae-Fix is a non copper based liquid algaecide that has had some success on green water. Since it has more residuality than Green Clean it can provide a longer term period of control.
I often suggest using a combination of beneficial bacteria and desired surface based plants to do two things. With the bacteria we’re attempting to reduce nutrients in the water that feed the algae and with the floating plants we want to provide more shading to block the sun exposure, which is also a big player in single cell algae growth. This approach is totally organic which many people prefer.
And finally, for chronic green water, it might be worth your time to investigate how a uv clarifier works. This is a very targeted treatment for green water and doesn’t involve using chemicals. It has it’s limitations on what it can work on (string algae is unaffected) but specifically for green water it has had a high degree of success.
Authors Note 7/2015 – Comparing peroxide based pond cleaners we’ve decided to replace Green Clean with a comparable, but better priced alternative called Algae Off. You can view that product here.