You will need a test kit to see what the current chemical values are. Balance the Ph first with either a Ph+ or Ph- chemical. Add chlorine, then shock the pool with a separate shock product and add algaecide. Be sure to follow the instructions on chemical containers exactly for the best results and NEVER mix any of the chemicals.
First thing is to make sure the the ph is correct. Once the ph is correct, make sure you are using the correct amount of chlorine. Make sure that the pump is on to circulate the chemicals in the pool. If algae has settled to the bottom, then vacuuming, to waste, once a week may be needed.
You can run an automatic pool cleaner for 2 or 3 hours a day. Bring a water sample in to any pool supply store for a free test to determine what chemicals you need. They should be more than happy to also answer your questions.