Not really sure why the 3 of the smaller ones are not doing the job.... might want to consider a "cooling box" which will keep the fog "hanging" around longer ... and you also might want to consider cleaning your 3 that you have ... maybe the pump nozzles are a little clogged and thats why the output is lower ? Most people buy those 400 watters that they sell at Wally World and they do , do the trick as long as you maintain them and treat them for what they are . If your not concerned with how much jingle you'll have left in your pocket after buying one ... then find a place that sells DJ equipment ( or I think Amazon also sells them online ) and get yourself a Chauvet Dry Ice Fog Machine or one of their 1000 watt fog fluid models ...