It’s an unpleasant surprise to find your pool water green. You may wonder if it’s dangerous, or if you’ve done something wrong, or even if your jealous neighbors have pranked you. Most likely, the reason your pool water is green is a chemical imbalance. There are several reasons your swimming pool water might be green in both inground and above-ground pools, and the fix will be different depending on which kind of imbalance you have.
When the levels are properly balanced, chlorine will keep the algae at bay, but the water will slowly begin to turn green as the algae take over if there’s not enough. But be careful—adding too much chlorine in pool water can cause those metals to oxidize and turn the pool a different shade of green.