If you read from the manufacturers site, it has the following text
"Suitable in use for commercial and residential pools... with a maximum CYA of 300ppm"
I have no idea why the max is 300, but nonetheless it is there.
Also, it shows a study of 6 pools, and 1 application reduced the pools CYA levels a range of 55-95ppm.
So I think that these guidelines are accurate for this product.
-If you have CYA of 300, expect it to take 3 or 4 applications to get your CYA back to an acceptable level.
-If your CYA is super high (>300ppm), the product will not work as it is out of range.
-Even if it did work, expect it to take at least 1 application per 100ppm drop, and as the product is not cheap, it is going to cost a fortune.
-Most pool stores can't measure above 150ppm, so if they say 150ppm, dont believe them that it is only 150ppm. While at the store, go ahead and dilute your sample 2:1 or 4:1 and ask them to retest. (and I know how everyone here feels about pool stores test, but I want to get this info out there for people to read in case they do go get a test done)
So far I think that people are treating this as a water rescue method once your levels are off the chart high, but as I think about it, I dont think that is the intended application for this product. For this product, I believe that this is what they are trying to accomplish. To allow them to use chlorine pucks, and occasionally use this to maintain safe CYA before it gets to high. In other words, a perpetual money grab by them.
So it is my belief that they think this product should be used like this:
1.) Use pucks in your pool
2.) Once yoru CYA gets to 100ppm or so, add an application of CYA reducer, and you will get back down to an acceptable level.
3.) Repeat steps 1 & 2 over and over.
Someone much better with chemical math than me can probably give a more accurate answer to this, but with this philosophy (which seems like a bad philosophy) if you have a Memorial day to Labor day season, you could use pucks, and once or twice during the season add this $50 product to keep the CYA manageable.
Thoughts on my theory?