high CYA and phosphate reading

[vivian]

I just found this website and its great! thanks to everyone who contributes.

I have a inground plaster pool which is about 30,000 gallons, and a sand filter.

Here is my water analysis report that I got at a pool supply center today:

Total Chlorine 5.0
Free Chlorine 5.0
pH 7.4
Total Alkalinity 110
Calcium Hardness 500
Cyanuric Acid 150
Total Dissolved Solids 600
Phosphates 1000

The pool store talked me into buying a bottle of Sea Klear phosphate remover, but after reading some of these posts I am not sure if I should use it.

They said my chlorine levels were fine, but also after reading some posts it sounds like that I should have a higher chlorine level because of the high CYA of 150.

I am using stabilized chlorine tablets, which is probably why the cyanuric acid reading is so high.

Should I shock the pool tonight with calcium hypochlorite?

Should I be adding chlorine beach regularly in the evenings, in addition to the stabilized chlorine tablets, to keep a high chlorine level?

Any advice would be appreciated!!