high calcium

[alisonquilts]

I finally have my new testing kit (K-2006C), and I am enjoying revisiting basic high school chemistry labs. Most of my numbers are good (see below) but my calcium is way too high. Partly this was due to me buying into the pool store mantra, and partly due (I think) to the pool store test being grievously inaccurate - the last test I have from them was three weeks ago, after I had added the last of the calcium they recommended, and read 275 ppm; my test today (done three times out of sheer disbelief) reads 420 ppm!!

I have a SWCG and I am not seeing any scaling problems so far with this Ca++ level, but I would prefer to deal with it and get it down. What I am thinking of doing is sucking water out of the deep end through the bottom drains (with the pump on 'full drain' setting, no skimmer, and water going to waste) and simultaneously have a couple of hoses of tap water pouring into my shallow end. (Tap water CH is 40 ppm.) I feel this is the best way for me because of the extreme shallowness of the shallowest part - 9" - and the need to keep a certain depth over the liner at all times. Here's my question: what is the minimum depth of water (and thus weight) required to keep the liner from lifting? 4"? 5"?

Thanks in advance for any advice, or suggestions!

Alison

test results, midday, water temp 81F:
pH 7.8 (going to dump in 1/2 gal muriatic this evening)
FC 2 ppm
CC 0
TA 100 ppm
CYA 50 ppm (going to the pool store to get more tomorrow)
CH 420 ppm (aaaahhhh!!)