Backswimmers

The key to getting rid of backswimmers is algaecide! I live in Louisiana and have spent several weeks fighting with backswimmers. I've been removing them all day every day with a net and stepping on them only to have more the next morning. Our pool was crystal clear, in balance, and no obvious algae... but they would still fly in all day long and I'd have to scoop them out. Our pool is turquoise blue fiberglass, 12000 gallons, and salt water. I was starting to think that the bugs just liked our color better than our two neighbors' pools. They have not had the issues we have had. I've concluded that the difference is that they both use the same pool guy who adds algaecide weekly. I decided to buy Back Up algaecide by BioGuard after reading everything I could online about backswimmers. I added 2 oz every night for 3 nights and hopefully I can now just add 2 oz every Sunday and keep them under control. Backswimmers cannot get to the surface for air with this stuff sitting on the surface of the water. Every morning I just see dead ones now... Some on the bottom and some still floating on the surface, and some in the filter basket. I throw the Dolphin vacuum in for a cycle and skim the top which takes me about 5 minutes. I no longer worry if I see a live one show up because it will be dead within minutes anyway. I'd still like to know where they are breeding. My theory is in the French drains under my flower beds. Even if I found them though, I'm not sure if I should kill them since I read that they keep mosquitos down and we rarely see a mosquito in our backyard.