Green Algae
Green algae usually begins to grow in water that is low on chlorine. Often the water will be cloudy and then turn murky and green. If left untreated the water can turn brown and even black in the worst cases. Cleaning it up is the easiest of the three.
1. Balance pool water: Try to get the PH (acid) level between 7.4 and 7.8. You may need to add muriatic acid if the PH is high and soda ash if it is low.
**Note** if you are having trouble getting the PH into the range above, test your tap water. I have found some pools on well water may have a very high or low PH depending on the area. If this is the case, proceed to the next step and don't worry about the PH level.
3. Backwash filter (if filter is cartridge type, clean elements) : Often the organic matter that is causing the algae is in the filter, cleaning it now will improve chances of completely removing algae.
5. Shock pool : It is essential to increase sanitizer levels to eliminate organic matter that algae feeds on. Salt water pools will not reach this level without adding Chlorine. I recommend Calcium Hypochlorite(Cal-Hypo) because it has a high percentage of chlorine and it is the least expensive. Normal swimming range is between 1 and 3 ppm. In order to kill this algae, you will have to keep the Chlorine above 20 ppmfor several days. Shock the pool daily until desired level is reached and water turns from green to blue.
**note** Salt pools are chlorine pools! adding chlorine to these pools is safe and will not have negative affects on the system.
6. Chlorine Tablets: Addition of Chlorine tablets will help to keep the chlorine level high during the removal process. Tablets are slow release chlorine whereas shock is instant release. I use a chlorine float, the benefit is that even when the pool is off chlorine is still being added to the water.
7. Backwash again: This second backwash is very effective in the algae removal since all the algae that you have killed is now in the filter. Removing insures it will not come back.
8. One last thought. For best results give it a week. Brush and shock daily, remove bugs, grass clippings and leaves daily, keep the Chlorine floater full, run the pool 6 to 8 hours daily and backwash or clean filter. It will take some time for chlorine to drop back to normal. If water feels itchy, its to high, give it another day.