New pool user maintenance tips

I am a new pool owner and recently started maintaining my pool. It appears the Chlorine level is a bit high even though the pH is normal. I took the 3" Chlorine tab from the pool and it has nearly been a week. Is there something I should do apart from taking the tab off? TA and CYA levels are fine but the phosphates are a bit high at 500. Is that something to be worried? Can you tell me what is all I should be doing on a weekly basis even if all the readings are fine? Should I be adding stabilizer or shock every week? BTW, I took water sample to Leslie's and they suggested adding Phosfree. Is that really needed?