I have used the Diamond Crystal water softener salt in the blue and in the yellow bag which are 99.7 % salt.
The pool salt is just smaller crystals which dissolves faster and has no additives.
The minor additive in the water softener salt is Sodium Hexametaphosphate.
This product is used in the Boiler industry as a water softener, and anti scaling agent. It is used in detergents, in paint and printing products to keep the pigment evenly distributed and in the photographic industry. In the textile industry it is used to treat hard water to allow the dye to "wash out" properly. It will prevent soap scum from forming on the fabric and interfering with the dyeing process. It makes the color of the yarn even and bright.
Do you remember the old commercial for CALGON? "Ancient Chinese secret". The origianal formulation of Calgon was Sodium Hexametaphosphate.
It is even used as a preservative in some of our food products.
Crest toothpaste uses it in their PRO-Health whitening formula paste.
"Sodium Hexametaphosphate, which delivers cosmetic benefits, is an advanced anti-tartar/whitening agent that works with a combination of effective, but gentle whitening agents that polish away extrinsic surface stains and protect against new stains"
So it softens hard water, helps reduce scaling in hard water, controls Iron and Manganese, helps with corrosion control, prevents soap scum, and reduces tartar in my pool :lol:
Seems like it would be beneficial to have this product in my pool water.
From the MSDS the concentration of SHMP in the salt is .03%
So in a 40 pound bag there are 640 ounces. 0.03% is .0003 X 640 = 0.192 ounces per bag.
Don't doze off on me yet. Stay with me. I see your eyes starting to glaze over.
ppm= (1 lb x 120,000)/gallons of water. Say my pool is 30,000 gals
1 pound in my pool would be 4 ppm so 1 ounce(4ppm/16 oz in pound) is 0.25 ppm or 250 Parts per billion.
250 x 0.192 = 48 ppb
So yes, each bag could theoretically increase the phosphate level in my pool by
48 ppb.
A 10,000 gal pool could theoretically have an increase in phosphate level of
144 ppb with each bag.
I have never tested the phosphate level in the water, but surely it must be in the thousands by now with all the softner salt I have used over the years. I don't have issues with algae even under high heat and extreme bathing loads. The water looks clear, has no smell, and feels soft.
Phosphate rich water provides an excellent environment for algae to flourish.
Maybe I should run out and buy some of that expensive phosphate remover.
On second thought, I will simply continue to maintain my free chlorine level at 6-7 ppm with the SWCG and a CYA of 80 and not worry so much about phosphates.
Source:
http://www.phosphatesfacts.org/pdfs/Pot ... atment.pdf
