I just read about a product called Phoslock in the aquatic control newsletter. It is not alum based but "a lanthanum modified clay" that binds to free reactive phosphorous. Here is a quote from the newsletter. "Treating a typical one acre pond that is 4 foot deep with 2.5 pails (40 pound pails) of Phoslock will remove 80 ppb of phosphourous from the pond. This is significant because 80ppb of phosphorous provides enough fuel to creat 400lbs of algae in that same pond." They go on to say a nutrient test is recommended to determine the necessary amount to remove the phosphorous from the pond.
Regarding the current algae problem...raking is always a better fix than using chemicals as you are eliminating the nutrient cycling you get from the chemical treatments but it is obviously more work. I do like cutrine for algae but it is a band aid. If you can treat it chemically and you maintain the shade of the dye and you have the bacteria and aeration system you might be able to minimize the regrowth. Otherwise it is sometimes necessary to repeat cutrine applications every 2-6 weeks depending on the severity of the problem. if you dont physically remove the algae with 90% percent coverage it would probably be recommended to treat no more than half of the pond, wait 10-14 days and then treat the other half.
I found that just the other day surfing the net for Algae solutions...
Interesting quote from their website:
Treatment with Phoslock provides a “reset” of the ecological clock of the water body. That is, it returns the water body to the phosphorus level which is likely to have existed many years prior to the events which have given rise to the increased levels.
Management strategies limit additional nutrients finding their way into the water body. However, it is rarely possible to prevent nutrients building up as there are various sources including runoff and waste from birds and animals. Phoslock may remain active and capture phosphorus from natural sources for many years.
