Pool chemicals have tested out fine, if anything ph is a little low. Couple days ago shocked and this evening saw noticable piles of debris so I vaccuumed...what I saw was a bunch of little white, ricelike worms/larva/ ??? They are about size of a quarter of a piece of rice.At first squirming when out of pool , while vaccuuming noticed alot floating in pool as well. So next day I super shocked and called local pool experts. They recommended algaecide. Did that and vaccuumed up half of what I did first day...all dead yesterday. Evening vaccumed again and now only a bit. What are they? R they harmful? How do I get completely rid? First time poster...new member... Thanks! Not mesquitos!