Need 2nd Opinion on % vs Volume vs $ calculation/assumptuion

[giroup01]

<sigh> a second update...
I wanted to work the angle on giroup01's suggestion of using CalHypo...
I have been searching around for info on whether CalHypo will increase my Calcium levels (which it will...so forget it)

Keep in mind that the pool will be opened about 4 months a year, and come October you'll drain it 2/3, whatever's left will be diluted by rain and melted snow, then you'll top it off in April with tap water.

So the increase in CH, whatever it is, is irrelevant.

[Sponge1971]

Well, not quite...

I have a DE filter so I don't dump & fill on a regular basis. Rainwater duming is all I'll be doing.

I plan to close my pool way late and open it way early. This is my first run but I'm thinking April to November...we'll see how reality goes...

I also only plan to drain below my returns, leaving them open to allow overflow to drain out the pool. Opening 'refill' will only be about 6 inches.

I have no idea on the 'rate of rise' my calcium would have, if I used CalHypo...but there won't be the dilution you're suggesting.