Safety concerns. Always marinate meat and fish in the refrigerator. You can use some of the marinade for basting after removing the meat or fish from it only if you bring the marinade to a boil and cook for five minutes to kill any bacteria.
Running the pump at night should only be when you are doing a major chemical treatment such as algae clean-up. Your pool is more vulnerable during the day, plants don't grow at night the way they do during the day--that's true of ALL plants including Algae.
A correctlysized pump, however, moves the water through the system and sends it back to the pool, filtered, cleaned and ready for swimming. A pool pump should run a minimum of 12 hours a day to turnover, or filter, all the water in a pool. A number of factors can reduce the amount of time required to filter the pool, one of which is the gallon size of your pool. How big your pool is determines how quickly your pump can complete a full turnover of all the water.