There are several nutrients that can affect algae growth in a pond, but none are more potent and stimulating than phosphates. Simply put, without phosphates, you would have no algae bloom, and the higher the phosphate levels, the more aggressive the algae will grow!
A good beneficial bacteria will target all the various kinds of nutrients that feed unwanted growth and it will work much of the time to help clean a pond up.
But sometimes these good microbes simply may not be enough to reduce the phosphate levels down low enough.
When you have a stubborn algae bloom that you can't seem to bring into line, then consider checking the phosphate levels in your pond. Even low levels can stimulate algae.
If you choose to target them a bit better, there are several types of products that can help. All of them work to bind up with the phosphates and make them unavailable to feed algae. Alum is a common chemical that works on phosphates, but it comes with some risks to fish. The pH of your pond water must be relatively neutral to use it safely. This is why we rarely if ever use Alum exclusively.
Fortunately there is another solution. We have a non-chemical, natural calcium based product that works very well to bind to phosphates without affecting pH to a great degree. It works a bit more slowly than Alum, but is a viable option when safety for fish is your highest priority.
Plus there are other benefits...
Currently we offer two sizes of the phosphate binder. You can find these listed below. Dosage rates are approximately 3 to 5 pounds per acre foot. For small ponds, 1oz per 500 gallons. Higher dosages or repeated applications may be necessary if phosphate levels are particularly high.