Quote Originally Posted by SunnyOptimism View Post
Does anyone have any links to threads regarding the use/efficacy of liquid chemical cover products like COVERFree? These would be any products that use hydrophobic fatty acids (eg, stearic acid) to create a monolayer film on the water's surface to reduce evaporation.
I didn't find too many links here on this forum (could be the search engine), but at TFP there are a lot of threads about liquid solar covers and COVERFree. This post of mine lists various chemicals used for this technique. They basically do work to cut down evaporation by around 80% if the air is still (compared to nearly 100% for a traditional bubble-type cover), but when there is wind or if the pump moves the water too much then their effect is reduced considerably.

As teapot mentioned, if the film is disturbed enough to get sucked into the skimmer, it will get caught in the filter similar to what happens with suntan lotion. As for encouraging bacterial biofilm, that may be more of a problem in sand filters where channeling could occur as a result. In cartridge filters this doesn't seem to be seen as much, perhaps because chlorine is more consistently and evenly distributed in spite of such film getting caught into the filter.