I used Alum/lime treatment for clearing green water and it worked great. Visibility went from 9" to 36". It was a job to add enough to clear a 3+ acre pond but well worth the effort. There was a downside and by clearing the water the plants took off. Before the treatment i had no plants growing in the water.
Tracy, this post really piqued my interest. As I mentioned before, I am keen to understand whether nutrients that are deposited by the Alum treatments are lost to the ecology of the pond. For example, is phosphorus bound such that the plants cannot free it for their own use? Are the nutrients in organics of the detrital algae that were flocced and deposited available to detrivores and bacteria?
I have to consider the question of whether foccing all the algae and sending it to bottom doesn't greatly limit the nutrients available to the ecosystem. Perhaps the nutrients, rather than being in solution, are now only available to rooted plants (as opposed to plant that source nutrients from the water column ... algae). If so, the excess nutrients are not really removed and other organisms will fill the niche that the treatment caused. So we need a deeper understanding. If one is applying Alum as a solution for green water, it may be tempting to consider the treatment as a success ... that is ... until the cascade effects become fully evident. In may way of thinking, I think would rather deal with excessive green water than have to deal with excessive growth of rooted plants.
