Calcium Hardness in Pebble tec pool

I've never had this come up before but last time I had my water tested at Leslie's they warned me about my low CH levels. I did just refill the pool this season with city water.

Just tested the pool and here are my results.
FC-3.6 (already added another lb of dichlor)
PH-7.6
CH-250

I'm not very certain I'm doing the CH test correctly though, K2006 kit says red should turn blue with the drops but It's hard to differentiate from when it turns purple then blue.

Anyways, where should it be? I would have to order Leslie's "Hardness Plus" as they don't carry it in the store.

Thanks!

Check the poolsolutions.com guide:

http://poolsolutions.com/gd/poolsolu...guide.html#cal

Recommended levels of Calcium Hardness for a hard-sided pool is 200-400ppm. Sounds like you are fine.
Recommend levels od calcium for a vinyl pool is 0....not needed.