Quote Originally Posted by michael3 View Post
how long does it usually take
There's no answer to that, except to say that it depends on what's in the water, and your filter. I once spent the night babysitting a vacuum DE filter that was below water level on a 240,000 gallon Girl Scout pool: it was stopping up ever 15 minutes due to an algae infestation, and would flood if not cleaned and handled promptly.