GLB Drop n’ Vac is a non-alum flocculant that settles floating debris and material the filter can’t get, such as microparticles and dead algae, to the bottom of the pool. This product works overnight and allows for easy debris removal by vacuum. It has been recently reformulated to work over a wider pH range. It also now contains a clarifier. Drop n’ Vac is safe for all pools and in conjunction with peroxide-based sanitizers. It is compatible with chlorine, bromine, salt water pools, ozone, and biguanide sanitizers.