Following the dosing recommendations on the bottle of Polyquat usually works well. If you have visible algae growth, start with 16 ounces per 10,000 gallons and then use 3 ounces per 10,000 gallons weekly. Unless your pool is very large or you lose a lot of water from backwashing and splash-out, you may find that using 50 ppm Borates is more economical as it is mostly a one-time cost. For example, for 10,000 gallons, the maintenance dosage of 3 ounces Polyquat costs around $1.80 per week. 50 ppm Borates in 10,000 gallons would need 7-3/4 76-ounce boxes of 20 Mule Team Borax @ $2.50 each plus 282 fluid ounces (2.2 gallons) of full-strength Muriatic Acid (31.45% Hydrochloric Acid) @ $5/gallon so about $30 one-time cost. Or you could get 24 pounds of Boric Acid @ $27.75 per 15 pounds so about $44. Again, this assumes 10,000 gallons so scale up or down accordingly.