I have been making media for years and recently have had standing water problems on the lids of our inverted plates (1-2mls of water), as if the water is falling out of the media. This has never occured before, we have not changed our suppliers or protocols. We use Criterion PDA, but I had acess to Difco PDA for a test and the same thing occured. We cool the media to 50 degrees before pouring and allow the plates to sit till cool before bagging. We have tried refrigeration and room temperature in a temperature controlled growth chamber. We have also tried adding extra agar to the recipe. Anyone have any ideas? Next we are going to try sealing the plates with micropore tape instead of parafilm to allow some air movement.