CH 200 ok for plaster or raise it?

[PoolCleanerMom]

today's numbers, 17,000 gal rectangular plaster pool. Our municipal water is fairly soft.
FC4.5
pH 7.6
CYA 40
TA 100
CH 200 - I see the recommended range is 250-350 in Pool School. How important is it to keep the CH at the lower end of the range (i.e. do I need to head out to the pool store now to buy calcium adjuster, or is it a sometime-within-the-next-few-days-or-weeks thing?
thanks!

 

[Texas Splash]

If you have naturally soft water that doesn't really increase CH very fast, you have two options .... buy some calcium chloride or calcium chloride dehydrate products to raise CH, or .... buy a few bags of Cal-Hypo chlorinating shock. One of the rare times I'll say to buy something from the pool store. Use the Poolmath calculator (Effects of Adding Chemicals) to determine how much CH will increase with X-number of bags (ounces) added. Plus, you're increasing FC at the same time. You can spread it out over time for the next few days or so.

You don't want CH too low or it tends to compromise the plaster on your pool surface.

 

[PoolCleanerMom]

Thanks! Will stop at the pool store this weekend. Does Cal-Hypo raise CYA much or is that the dichlor shock that does that?

 

[Texas Splash]

Not at all. Tri-chlor and di-chlor do, but not Cal-Hypo. Cal-Hypo will only raise CH. You can enter some test numbers into the Poolmath calculator and it will tell you almost exactly what to expect.