I suppose if you want to spend a lot of money it is ok but you are having the annual algae attack that just about every ponder has in the spring. You can deal with it better with a UV light in the filtration system or you can wait the two weeks it usually takes to run its course. You should get rid of the muck because it is feeding the algae. You don't mention anything about filtration systems. Most of us use a filter of some sort and it is there that you will find aerobic bacteria (that means beneficial bacteria) working away to give us clear healthy water. We don't need to add extra bacteria except in unusual cases because it grows naturally in our ponds. So long as there is sufficient oxygen in the water and nitrites and other chemicals are kept under control, beneficial bacteria thrives. Look at the FAQ on algae and do a search on the subject to learn a little more about it. After you get rid of that mulm on the bottom you need to put in some plants to use up some of the nutrients in the water and shade it to reduce the conditions algae like. Personally I think that device is way out of line price-wise. Sandy

Thanks for the response sandy. My pond is very old and is basically natural except that we had it deepened over 30 yrs. ago. I holds maybe 500,000 gals. of water so it far surpasses your garden variety water feature. It gets run off from 2 farm fields as well as ground water from my sump pump and despite my best efforts it gets a lot of leaves in the Fall & Spring. It has an abundance of muck on the bottom and for me to try to clean it out manually is a little impractical. The device I spoke of is supposed to digest the muck and convert it into water & co2. I read this forums FAQs page and although it does address the algae problem for smaller ponds, it doesn't seem to help in my situation. I would like for someone who has used the biosphere or a similar method to tell me what they think of it.

Pictures of my poor pond.

http://photos.ivillage.com/images/photos/resize/gardenweb_Garden%20Galleries_1239831774966_71169D.jpg

http://photos.ivillage.com/images/photos/resize/gardenweb_Garden%20Galleries_1239831846557_252400D.jpg

I don't know if it will clear up your algae but an aerator will certainly improve the water quality if the water is not running. You can also suction the muck off the bottom by renting the appropriate pump and hose system. It would make great fertilizer.

I have some experience with two ponds shallower than yours that both had the same type of floating algae. What we did was add a large floating fountain to one. The added oxygen really discourages that type of algae and made a vast improvement in water quality. The other is still a mess in the summer time. Here is one link to a fountain. It's important to draw water from somewhat close to the bottom as this one does.

Here is a link that might be useful: water fountain

Thanks for your help! I will look into these options.
Jim

Jim, while there are obvious differences in a lined pond and a natural or clay bottom pond, the theory of algae control is the same. You have to eliminate the food sources and supply additional oxygen.
Dredging is normal maintenance for a pond the size of yours. It doesn't eliminate all the nutrients feeding the algae but it is a start.Until that is done nothing else will be effective. The runoff is an additional problem. You can add plants to the water and the shoreline to use up some of that food but that type of plant can add debris from winter kill so you would still have to get rid of the debris eventually along with any other leaves that blow into the water. The Michigan DNR has some good advice on plantings and the Ohio DNR and Ohioline have some as well. The lakes in Wisconsin where we used to live were dredged on average every 3 years but those were much larger and were used for swimming and boating as well as providing for wildlife. They were marvelously clear.
This all presupposes you want to keep the fish and other critters. There are chemicals that kill algae very thoroughly, but they essentually sterilize the pond and only the strongest critters survive if any. There are products that shade the pond, eliminating the light that algae needs to grow but most of them contain copper sulphate or other forms of copper and that can kill the critters too. Adding microbes and enzymes to the pond can be done easily on a regular schedule but to work properly they require good oxygen levels. The device you mention adds enzymes gradually but doesn't supply any additional oxygen. That is where the fountains mentioned above come in or some other type of aerator like a waterfall or barley straw which supplies hydrogen peroxide as it rots.(recent studies suggest barley straw is not effective) Water that seeps into the pond is oxygen deprived as is the water from a sump. In addition, that device and everything else is based on maintenance from a dead start with a clean pond, which you don't have at the moment.
It is usually easy to tell if there is insufficient oxygen in the water. There is a hint of sewer in the air. The odor is being produced by that muck on the bottom. If it has not been dredged in 30 years it could be several feet deep. One way or another you will have to deal with the muck even if it calls for hip waders and gas masks. Sandy
PS, recently I helped get info for the restoration of a 5000 acre, 23foot deep artesian supplied pond. The info from the Michigan DNR in particular was very helpful.

Bacteria products can be very helpful in naturally removing that muck on the bottom of the ponds, however being that it is a natural process, it can take some time depending upon how much muck has accumulated. As sleepless mentioned, adding a fountain or some sort of aertation will greatly help and will cause the bacteria to be more aggressive at eating the muck. As far as additional algae control goes, have you looked into dyes? They could be a big help since you mentioned sunlight is a problem. Also might look at adding some plants to also help with the excess nutrient problem.

As far as those biospheres go, cant say I know much about them. Check the link I am leaving below for some good bacteria options, especially the blocks. They sink and will dissolve right on top of the muck.

Here is a link that might be useful: pond bacteria