If a new pool with a salt system has algae and the pH is high do you add salt for the algae and muriatic acid for the pH and how much salt would be needed for a 15000-gallon pool?

It's a bit more complicated than that. I would shock your pool first (use liquid shock that is made for salt pools, and our pool guy has told us it's the same as plain old chlorox)... That should start to get the algae down. At the same time add salt to get the ppm up to around 3500ppm... if you're under 2700 you won't be producing chlorine, therefore you aren't really helping your water at all. Then I would start on the pH. I learned something this year that was very helpful... your alkalinity is the ability of your water's pH to move into the right range. So... get your alkalinity right first, then your pH second. There's a technique called "acid balling" that helped my alkalinity a lot. Wait til the pool turns off at night, then pour a whole bottle of muriatic acid in, all in one place. That helps your alkalinity come down a lot. Then just keep adding muriatic acid during the day (wait a few hours at least in between to see how far you still have to go, test, then add more if you have to.) until you get to your goal! Hope that helps... I'm not a pool pro, but have a 30,000 gallon salt pool, so... good luck! Yank Ans:You just can't add a full gal of acid and never add the acid with the pump off. The acid will pool at the main drain at the bottom of the pool and then will be sucked into the pump, filter, heater when the pump is turned on - possibly destroying the heater. You need to test the pH 1st. If your readings are high - 8.0 then add no more 1 qt. at a time. Test the water in 20 min after circulation distributes the acid then adjust again until you reach the desired readings. Add a gal. of liq chlorine 12.5% to pool for the algae and brush the algae often or until it stops coming back. If tests tell you that your salt level is low add only enough salt to bring the readings to about 3200. FOLLOW THE INSTRUCTIONS ON THE SALT BAG. USE ONLY POOL SALT. Please do not follow the previous instructions.