In a final effort to get the yellow out of my water, I tried a third brand of sequestrant/chelating agent, Sequa-Sol It worked. The water is the best looking it has been to date. The previous two were Metal Free and Sea Klear Metal Klear. The MSDS on this new one says the active ingredient is Sodium Citrate. It is listed as a chelating agent where the previous two used Acrylamide-Acrylic Acid Copolymer, listed as a sequestrant. I can't find much that explains the difference, at least as it pertains to pools. I am trying to understand why this worked and the metal free that worked last year didn't this year. Does groundwater change that much year to year?
Differences in Sequestrants
- Thread starter crokett
- Start date
MetalFree uses EDTA as the chelating agent. I have corresponded with Naturalchemistry about their choise of EDTA since it has a high chelaton index for calcium. I suspect the SeaKlear product is similar since I know it is not phosphanate based but I do not have a MSDS for it so I am not sure what is in the Seaklear. Both of them are 'phospate free' and not that effective. Sequa-sol by GLB uses phosphonic acid derivatives, most likely HEDP, just like the Jack's Magic products and Proteam's Metal Magic. I am looking at the MSDS for it as I type this. It does list sodium citrate but in the box above it says CAS Number: Not Established
Chemical Family: Phosphate
Chemical Formula: Proprietary Mixture
The MSDS is not necessisaily the ingredient list. By stating it's a proprietary mixture they can get around what is actually in it but by saying the chemical family is phosphate then it means it's a phosphonate since that is the main group of phosphate based sequesterants and HEDP is the most common one used in pools. The phosphonate based ones are also the effective sequestarants.
The Acrylamide-Acrylic Acid Copolymer is actually a polymeric clarifier. It's main purpose is to keep the water from clouding since sequesterants can cause the water to cloud if calcium levels are high.
Chemical Family: Phosphate
Chemical Formula: Proprietary Mixture
The MSDS is not necessisaily the ingredient list. By stating it's a proprietary mixture they can get around what is actually in it but by saying the chemical family is phosphate then it means it's a phosphonate since that is the main group of phosphate based sequesterants and HEDP is the most common one used in pools. The phosphonate based ones are also the effective sequestarants.
The Acrylamide-Acrylic Acid Copolymer is actually a polymeric clarifier. It's main purpose is to keep the water from clouding since sequesterants can cause the water to cloud if calcium levels are high.
waterbear said:
In layman's terms - albeit a bit simplistic - (and just to make sure I understand what I've read so far) this means the EDTA likes the calcium a bit more than it likes the metals, hence the ineffectiveness in my water? I want to understand why what I did works so I can repeat it next time.
With a vinyl pool, is there a reason I should test for calcium? I haven't been since what I read says it is a concern for concrete pools.
thanks for the explanation. It helped a lot.
Thanks Waterbear! I will start testing calcium again. IIRC I tested once at the beginning of the season and from the ground the water was at 120 PPM but I will retest.
On a side note, my neighbor's well is about 300' from mine but it is a few hundred feet deeper so he may be on a different aquifer.. As far as I know he has no problems with discoloured water. Can groundwater conditions vary that much?
On a side note, my neighbor's well is about 300' from mine but it is a few hundred feet deeper so he may be on a different aquifer.. As far as I know he has no problems with discoloured water. Can groundwater conditions vary that much?
Ground water can vary dramatically over short distances both horizontally and by depth. Often enough entire areas will be similar, but it isn't always that way.
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