1. The CuLator packs work very slowly. It won't hurt to have them in the pool, but I'd just suspend them near a return, anytime you are using the cal hypo.

2. The CuLator is probably best for long-term maintenance. Reportedly, it can collect iron that is chelated or sequestered. Cal hypo will not -- though it does have some tendency to 'break' the sequestration.

3. above.

4. Yes, add CYA. Or use some dichlor in addition to the cal hypo. If you buy a 24# pack of dichlor at Sams Club, it will add about 160 ppm of chlorine to your pool, and about 140 ppm of CYA (too much!). If you use the dichlor to quickly rechlorinate, that will immediately add some CYA. The 1# bagged dichlor will keep till next season, which matters, since you won't need it all this year.

5. I have not seen good results from iron testing: I've repeatedly seen pools stained when iron tests indicated no iron. So, yes, you have to wait for the stains.

6. Use a blended strategy: when refilling add a small dose of HEDP chelant; fill with softened water SLOWLY; fill via the skimmer after adding cal hypo tabs to the skimmer; keep Culator packs in the skimmer when not filling.

A couple of points:

=> I do not know that "Natural Chemistry" is intentionally selling products that are likely to produce apparent quick results followed later by failure. But if that WERE their purpose, they are selling the right products to do so. I'd recommend abandoning them as a supplier.

Their chelant is non-phosphate based . . . which means it doesn't add to the phosphate nutrient load and ALSO that it's not chlorine stable. Right now, with the chemicals available to the pool trade, there is a clash between maintaining low phosphates and using effective chelants. It is *possible* to do both, but the situation is not ideal.

What makes it worse is that there is no reliable supplier of plain HEDP (the desired chemical). The closest we can come is the Pink Stuff on Amazon. (Link in the stain sticky).

=> Working out a successful method of managing metals is an individual process, and takes time. I've done it several times on large commercial pools with challenging supply water, but it's always taken me a couple of seasons to get the process tweaked 'just so'. If there's an optimal one-size-fits-all approach, I haven't found it yet.