I have a 20 x 40 pool which has been very clear until the past several days in which we have had rain. I took a sample of water to the pool store and had it tested and every thing fell into the recommended range. The pool is surrounded by numerous trees; is there any correlation between the recent rain and the green water? Aslo, my grandchild had a pool party with many guest, my mom is adamant that swim suits that have not been washed and have been exposed to other pools with algae can cause algae to develop. Of course, after any heavy swimming or rain, I have shocked with the recommended amount of shock and I use chlorine tablets in a "floater" and add as the tablets dissolve. Again, the pool was crystal clear until the rain and the current free chlorine is 1.2 ppm. total chlorine is 1.3 ph is 7.8, hardness is 250 ppm, alkalinity (w stabilizer correction) 88 ppm and cyanuric acid is 40 ppm. Copper, iron, and dissolved solids were 0 ppm. Tonight I have added another 3 lb of shock, 4 oz of algacide, and have turned the pump off. I plan to vaccum to waste in the am. Right, wrong, suggestions? Thanks in advance for any advice.