A UV will not help at all with string algae. Shade will help a lot though....any way to put a shade sail over your pond? They look great and keep the water cooler too, which is important for the pond's critters.

Nope, a UV will not help with string algae. Shade will help, but you might also try barley bails or extract. Some people swear by them, even though I haven't seen much in the way of improvement. I've been using my trusty toilet brush and waiting for the pond plants to start helping.

I have a UV light and it is GREAT for preventing green water. I have never had green water as a result. However, it does nothing for string algae. I bought some barley hay that they sell at Petsmart in pad form and it cleared up the string algae in 2-3 weeks. I was pulling out gobs of string algae during spring (every other day) before I discovered the barley pads. Give it a try.

I have a 7,500 gallon pond and I have string algae. I have come to kind of like it. I didn't at first but now I don't find it's a big deal to pull it out or use a patio broom to scrub the waterfall rocks where it starts to get a little thick. I throw it around the other plants in my yard. Keeps the weeds down and feeds the plants. It does help to keep the pond cleaner till the other plants take over.

How do you use barley pads or balls? Do you just lay them randomly on the bottom?

A shade sail isn't really a viable alternative. There isn't a good way to anchor one. Also, at times, we get very strong winds.

Increase your shade to starve it of light. Increase your plants to starve them of food(plants that shade like lilies, water hyacinth or water lettuce are double dipper beneficials). Remove manually as much as you can and add barley regularly to kill the new alage. It will be a slow process but any solution by itself will just set you up for more battles in the future.

A good layer of it on the sides of your pond is a good thing. It is a great filter plant. But if you have it in balance it should be like a 1 inch or under fuzz on the walls. The algae needs sun and nutrients and more complex plant life will starve it. If you have a lot of it you either have too much sun or too many nutrients or both.

UV lights affect green water algae and will do nothing to string algae.

Definitely DO NOT use algaecide. All you will do is kill the initial crop and the decomposition will feed a stronger crop in a few weeks to a month and you will need to do it again. Great for the algaecide company but not for you or your plants.

Barley is essentially doing what David talked about above. Except that it slowly releases and keeps doing the job over a long period rather than with a shock the day you pour it in.

As the barley straw decomposes it creates hydrogen peroxide (H3O). The H3O is harmless to complex celluar life like fish and plants in small amounts but it kills the cells of string algae as they replicate. It won't kill existing algae but will inhibit to a large extent future growth. Soooo it needs to be the last phase after you have planted more and physically removed as much as possible.

If you use the proper amount regularly it will control your population. Keep in mind though that if you have a bloom of it, you need to have the barley in the pond a week or two before it starts working.

The issue with barley straw is fairly complex. It's not certain exactly how it works. If it was nothing but the release of low levels of hydrogen peroxide then it would be possible to set up a chemical dosing pump to add very small volumes over a long period of time. Although there are numerous discussions on the topic, that it has been researched in Great Britain, etc. -- there does not seem to be a single, peer-reviewed scientific paper where they have actually measured what it is released (and there are some exceptionally sensitive assays for peroxide and peroxide metabolites out there). The website below presents a discussion as to what may be going on, where they have conducted side-by-side studies. However, it too is not a peer-reviewed scientific study although several papers are cited (they do not have any measurements of what is being released). Regardless of all of that...adding barley straw is, as far as I am concerned, another of those "do no harm" things. You can add it and it may help. It won't hurt unless you decide to carpet your pond in barely straw!!! :-))

As to using vascular plants (water hyacinths, water lettuce, etc.) --- these will do double duty to provide shade and act as a phosphorous sink. You can help them to compete against the algae by adding no more than 1/2 tablespoon of potassium nitrate per 1000 gallons once a week (it goes under the name of "tree stump remover" in most gardening centers - if in doubt ask for the MSDS sheet on the product which they are required by law to be able to get for you).

The use of water hyacinths, water lettuce, etc. will also provide a very large surface area/root mass which will harbor a variety of "critters" such as daphnia that will go after the algae as well.
Hope all this helps.
---David

Here is a link that might be useful: Link to Purdue University, Dr. Lembi article/discussion

Boulder,

I placed 2 barley pads in my 1,000 pond about one month ago. I only needed one, but I really wanted to zap out my horrendous algae issue. At first, the pads will float, but the next day they should start to sink. I placed one in my biofalls waterfall area and one in the pond, disguised below some water lilies. Therefore, neither are visible. I've never used the pellets, but I'd like to try them after my pads wear off in a few months. I've heard from a fellow ponder they are even better. I got the pads bc the pellets weren't available at the store I went to.

You have to be patient for two weeks as it takes time for the pads to start deteriorating in the water. In no time, you'll notice the algae will stop growing.

The pads have been a true blessing as I used to clean out string algae literally every other day!!! The stuff was growing about 2 feet a day, seriously. I was a slave to the algae bc I had to pull it out so often. Ugh!! I don't miss those days. I don't have the algae problem AT ALL now. My husband is now a believer! He thought it was a crazy idea and didn't think it would work. He now sees the results and loves it.

Also, it did not do any harm to my other plants or fish.

Also...I'm not sure if the barley had anything to do with this, but since my algae has been "inactive", my pond plants have gone nuts!!! Everything is growing faster than I've ever seen.

Thanks for all of the great advice! I am going to get some barley and put it in asap.

Now I have another question. I have one large pond and a small pond connected by a stream with 2 waterfalls. In total, it holds about 5,000 gallons. Is it better to scatter the pads or put them in the stream so that the chemicals that get released are circulated throughout the system?

I'm not sure about placement and whether it matters as long as it's IN the water. I have one in rapid moving water and one in still water near my lilies.

I have a 6k gallon pond w/ waterfall and stream. I have 2 40 watt UV lights hooked up to 2 separate filters (although I'm in the process of building a variation of "Skippy's filter"). The UV lights do nothing for string algae because the algae has to pass thru the light to be killed, and string algae is attached and not free-floating. I tried barley pellets, and did not like them in that they turned my water brown. I started getting barley straw planters; they're like donuts-you put a potted plant in the hole, so they serve dual purposes-a floating planter and string algae controller(assuming barley works). I believe they help, but the barley takes several weeks to start rotting; that's when it releases the chemical. They come in 3 sizes; I get 2 large for my size pond and they last all summer. Also, on the UV light, you can't let the water flow thru the light too fast or it won't kill the algae and other critters. UV lights emit ozone, which is one of the best sterilizers known. I don't think the ozone created by these lights is the same wavelength as that in the atmosphere, and it has an extremely short stable existence before deteriorating, so I don't think it contributes to the smog-producing ozone. The bulbs only produce ozone for about a year (although they keep giving off visible light for much longer), so they should be replaced every year, preferably in the spring.