Originally Posted by Eastland
Originally Posted by Snipe
Originally Posted by Eastland
I find this thread interesting. I would appreciate input regarding 2 things. 1) if a pond needed 300 lbs of alum to clear and you applied 100 lbs a month for 3 months, would it clear after the 3rd application? 2) Since Gypsum is 10X cheaper than alum, does a small treatment act like alum, or will partial results be achieved?
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If a pond needs 300lbs of Alum to clear then 300lbs needs to be applied at one time.
Gypsum has about 5-10% of the ability to flocculate and sink particulates. It is more commonly used to raise Alkalinity.
Originally Posted by Snipe
Originally Posted by Eastland
I find this thread interesting. I would appreciate input regarding 2 things. 1) if a pond needed 300 lbs of alum to clear and you applied 100 lbs a month for 3 months, would it clear after the 3rd application? 2) Since Gypsum is 10X cheaper than alum, does a small treatment act like alum, or will partial results be achieved?
.
If a pond needs 300lbs of Alum to clear then 300lbs needs to be applied at one time.
Gypsum has about 5-10% of the ability to flocculate and sink particulates. It is more commonly used to raise Alkalinity.

Snipe, we seem to have different viewpoints. I find gypsum much more effective than 5-10% of alum. Todd Overton turned me on to gypsum as an alternative to alum, at $160 per ton, the results are a no brainer. Even small applications are noticeable, maybe it's the difference in water chemistry between locations.




I think several studies show Gypsum only works about 50% of the time and Alum will work 100% when both are properly applied. Cost can vary widely for both Gypsum and Alum, so I disagree with Alum being 10 times the cost, because application is different and can cost considerably more for gypsum...Every time I priced gypsum, Alum was considerably less expensive because it is not used in most areas. If forced to buy gypsum in smaller 40# bags the cost for gypsum per ton is $800...to keep comparisons fair, Alum is priced at $0.40-$0.60 per pound ($800-$1200 per ton). Overton has Gypsum listed as $195/ton currently...At 500-800 pounds of gypsum, or 250-300 pounds of alum per acre foot recommended "doses", final costs will vary, but unlikely that alum is 10X more.. To answer your question on alum "dosage"...If a pond needs 300 pounds of alum to be cleared, no, adding 100 pounds a month (or week) will not work, but if you add 150-200 pounds one day and it does not clear, you could add,100-150more pounds the very next day and it will likely clear...Alum does not dissolve in water, and slowly sinks...I have never used Gypsum, because when I am paid to clear a pond, using something that only has a 50% chance of working vs knowing I will accomplish what I am being paid for, Alum is truly a no brainer for me...and not much more expensive since it is easier to handle and apply...It all comes down to knowing what you want, knowing the chemicals, weighing the risks of success vs failure and true costs for the area and experience level, and making a personal choice on which to use

Last edited by Rainman; 07/31/23 07:14 PM.