Assuming that you were using a 10 ml sample for your chlorine test, the 0.5 ppm CC isn't a problem since it's really "<= 0.5 ppm". You could redo the test using a 25 ml sample where each drop counts as 0.2 ppm (instead of 0.5 ppm) since I suspect your CC is probably < 0.2 ppm. So I don't think you need to shock.
On the other hand, your FC level is too low for your CYA level if you want to make sure to prevent algae growth. Assuming the CYA reading of 90 ppm is correct, then you should shoot for a minimum FC of 7 ppm. If your pool gets a lot of direct sunlight, then a higher CYA level is OK, but 90 is probably too high. Something in the 60-80 ppm range would be better. Not a huge deal right now so you can just let normal water dilution take care of that. Just don't use any stabilized chlorine (Trichlor or Dichlor) or else the CYA will get higher. If you regularly backwash your sand filter, then I would expect the CYA to slowly drop over time.
Do you use any algaecide or phosphate remover in your pool or do anything else to prevent algae growth? If not, then you've probably got a pool low in algae nutrients (i.e. you are lucky). You can definitely keep algae from growing using chlorine alone, but I wouldn't take a chance with the low 2 ppm FC level you currently have.
As for the other measurements, you can use
The Pool Calculator to calculate the saturation index which in your case is +0.40 which is on the high side so could cause some cloudiness or scaling, especially if the pH, TA or CH were to continue to rise. The high TA you have would normally lead to a tendency for the pH to rise over time (especially with aeration) unless you were adding something to the pool that was acidic. If you find that you are regularly adding acid to the pool to keep the pH down at 7.5, then you could just keep doing that and the TA could get lower over time. However, if you have a lot of evaporation and refill and if the water is high in TA, then the TA could continue to climb (same with the CH). Use of a pool cover would virtually eliminate such evaporation. I suggest you test your tap water with the TF100 kit to see its TA and CH levels (no need to test for CYA -- there won't be any). If you want to lower the TA, then you can follow the instructions in
Lower Total Alkalinity.
Richard
:lol: 
