My name is Don and yes this is my first post to this forum. I have been reading up on my situation but have yet to get a definite answer. I have a reef tank and I have to put the water I use in it thru a 4 stage filtration system. Now to my problem. Came home about 3 months ago and the over flow valve had failed and I had a lot of water go onto the floor of my washroom and proceeded to dump down into a duct vent in the floor. I stuck my shop vacuum as far into the vent as I could and got about 5 gallons of water out of it. My house is 11 years old and I have looked as far into every one of the vents and none of them have hardly any dust in them at all. I have no clue how much water I did not get out but I'm thinking not a whole lot more because the process is very slow for the water to go thru the filtration system. My question is could the water that did remain in the vent duct ultimately promote mold to grow in the duct. I would imagine what water was in there would of had to already evaporated. I have a crawl space that is only about 3 foot high. The duct I would have to check is on the other side of the house from the crawlspace entrance. I not sure if any dumped into the main trunk but am trying to decide if I should go open everything up around where the water went in and see if any mold has formed or do you think the water may have just evaporated without causing any problems. The water is very pure and stripped of any medals or chemicals. Any assistance would be greatly appreciated.