Quote Originally Posted by PoolDoc View Post
+ Borax is about $0.65 - 0.75/lb at Walmart.
Thanks. I'll check out the local prices here.

+ A "natural" stain fighter could be a chitin (shrimp shell) product OR it could be a mined ortho-phosphate. Better not.
Sorry, are you saying I shouldn't use this brand of salt? What's the likely consequence of using it if it contains the things you mention? I've already used one 40lb bag of this in my pool. Am I likely to have some kind of problem? I bought 200lbs to have on hand for the season. Should I return it and go back to the brand I was using (I think they still carry it)?

+ Purple Stuff is one of 3 Jack's products that are HEDP, a chlorine resistant phosphonate. These eventually break down to ortho-phosphates and release the chelated metals.
I guess this explains the need for a regular maintenance does (add 12 ounces a week works to maintain the recommended level). I did know it breaks down into some kind of phosphate, but I was told it's not the same kind of phosphate that algae feeds on. Is this correct?

+ There are 3 possible strategies for removing metals:
=> CuLater zeolite-like patented product. Maker *claims* that it will remove phosphonate chelated metals. Available from Amazon:
1 ppm Culator, direct from Amazon
1.5 ppm Culator, sold by Amazon, shipped from Periodic
4 ppm Culator, sold by Amazon, shipped from Periodic
=> Flocculant use -- PAC (polyaluminum chloride) dosed slowly pre-filter should gradually remove metals.
GLB Pool & Spa Products 71408 1-Quart Drop n' Vac Pool Water Clarifier @ Amazon
=> Oxidation onto the filter with calcium hypochlorite.
(I've done this myself, repeatedly. But it's method dependent and if you are not careful, can result in stains.)

OK. Those are the options, but each as problems.

CuLator is zero risk and very easy; you can use it simultaneously with HEDP, and (reportedly) remove the metals while still protecting your pool with HEDP, because (reportedly, again) the CuLator material has a higher affinity for the metals than HEDP. But, it's unproven, and intrinsically slow, since you must pass all of the pool water over this little baggie sitting in your skimmer. You'd probably want to use it UNDER a skimmer sock, like this:
Poolmaster 16242 Poolmaster Skimmer Basket Liner
to keep from fouling it.

However, it's unproven. We think it probably works; but we're not sure how well, or what limitations may apply. Periodic's owner is a genuine PhD chemist but is playing things very close to the chest, and is really hoping to make a killing off his patent.

PAC should work, but will require regular attention to the filter, careful filter cleaning, and either many repeated small doses or jury rigged trickle feed into a skimmer.

Cal hypo oxidation onto the filter works, but is potentially dangerous (cal hypo does NOT play well other other chemicals - so NO feeders or devices or chemicals in the skimmer or the lines between the skimmer and the filter).
Ugh........it almost sounds easier to just keep using the Purple Stuff. I've been using it for several seasons and haven't noticed any negative effects, well maybe a little to my wallet.

I'm curious about the cal hypo method. Could you elaborate?

Thanks.