You need to get your pH up as soon as possible. You can raise pH and alk at the same time by using washing soda, or by using Borax for the pH and baking soda for the alk. You also need to make sure you get adequate chlorine in the pool before you get algae. With no CYA that mqy mean adding chlorine multiple times daily. With a gunite pool, you also need to get your cacium levels up, so using cal-hypo to chlorinate would kill both birds with one stone.