I just leased a house with a 24×40 inground plastet pool. The pool had not been used isn a yeat or two and the cover had fallen in so there was a bunch of debris in it and the water was very green. I have spent the last three weeks leaf raking and treating the water. I have the chemistry ballancd and have been pooring the chlorine to it trying to get it to clear. I have put in a total of 125 pounds of granular chlorine. I read where you need to keep the chlorine level very high to kill all the algae. The water is still very cloudy and green. Not dark green but a light green. I have also added bioguard banish. I still cant see down but about 12 inches. So I let the chlorine level drop to a safe level and went in to investigate. Some leaves are still hanging out in the bottom and I did find some algae growing on one of the walls. So I brushed it down… by the way I have been brushing it down everyday. Anyway the color and cloudiness have been unchanged for two weeks now. I started to think maybe my problem is a filtration problem. I contacted the owner and he said the sand was changed in 2010. So my question is can sand go bad if it sits in the filter unused for a period of time. I dont mean bad as in spoiled or sonething. Could my problem be filtration even though the sand was replaced recently?


Yes, the sand can be a big part of the problem. Since the sand sat dormant (and likely moist) for an extended period of time, it is likely that there is contamination in the filter itself. It is recommended that the sand be changed at least every couple of seasons and it is a pretty easy and low cost fix that will help significantly.