hmm, you are about to stump me. It sounds like, for some reason, you are having a lot of nutrient added to your tank. that can come from food if you are feeding a TON every other day or die off in your tank - losing a coral you missed, mass suicide of snails or crabs, something like that. It should correct itself over a bit of time. Just keep up with water changes and let your tank run its course. It really takes a year for your tank to get seasoned and truly balance out. 40ppm isn't the end of the world and there are worse problems to have. Hell, I can't ever get my phosphate under .5 because I feed like crazy - but it doesn't seem to effect my corals (except when I try pom pom xenia - each time I have tried it, no matter where I buy it, it shrivels up within minutes from entering my tank. Weird). Anyway, keep with it.
-Dr Marco :sfish: