Every algaecide I've seen in stores has either copper compounds or ammonium compounds. Copper stains pools, hair, clothes, etc. Ammonium compounds are broken down by chlorine. So one chemical is essentially an organic waste product you add another chemical to destroy, the other will turn your pool and everything that goes in it green.
If you take nothing else from TFP, learn to look at the labels, see what's in each product, and what the ingredients do. I learned the hard way, dumping "clarifier" in hoping for a miracle. No ingredients listed, so it's snake oil and voodoo as far as I'm concerned.