I opened our pool today...it was perfectly clear! I attribute that to this forum and the BBB Method. Even the heater started right up. The only thing new this year was that when I fired up the heater (Hayward H200), I noticed black smoke coming out of the vents. I shut of the heater, waited 15 minutes and turned it on again. Black smoke again. The smoke has left soot on the vents. The water temperature is only 55F. Any ideas what the problem could be?