Water bugs in a swimming pool are difficult to kill using standard pool chemicals. You may try shocking the pool repeatedly or use a large amount of algaecide to remove their food source, but that won't work. Luckily, there is a very simple and inexpensive method for water bug removal. Water bugs must come to the surface to breathe. They stand on top of the water to do so. The following method changes the surface tension of the water so that they cannot stand on the water, and they cannot make the necessary bubbles of air to carry underwater with them. They will drown and then get taken out with the pool's filtration system.
Put 3 tbsp. of liquid dish detergent into the spray bottle.
Fill the remainder of the spray bottle with water and mix together.
Spray your soap solution directly onto any groupings of water bugs you can find.
Spray the solution into the water along the perimeter of your pool.
Wait a few hours. The bugs will drown and get cleaned out by the pool filters. You may repeat this procedure as often as necessary. The dish soap is PH balanced and biodegrades. Small quantities will not harm your pool.