You can make a dwc using a floating piece of styrofoam and a tray which will hold water...and an airstone with pump of course. Just do it until the stem is long enough so you can get a neopreme collar on it. No medium needed and no chance of tearing the root while moving to aero. You can use...
^^^^^^^^ that looks like a great deal as well. Here's another very affordable mixed flow fan you can use from home depot
http://www.homedepot.com/p/Unbranded-VENTS-105-CFM-Power-4-in-Mixed-Flow-In-Line-Duct-Fan-TT-100/204594854?MERCH=REC-_-product-3-_-203227157-_-204594854-_-N
any chain will do...
http://www.homedepot.com/p/Everbilt-3-x-1-ft-Steel-Tenso-Chain-806426/204630486
jack chain has easy to open links for quick adjustment.
This one will do the trick, but you have many more affordable options which will do the same job if not a better such as option 2.
http://www.homedepot.com/p/Suncourt-4-in-Centrifugal-Tube-Fan-with-Cord-TF104-CRD/203227202...
That sucks...I guess it would be easier to just use cig papers if getting caught would result in such a fine. Hindsight is always 20/20...I know. Never understood how some people walk/drive around with these items on their person if it's illegal. If you don't want to give up your...
Get a feel for the weight of the pot watered and almost completely dry, and get used to fingering the soil to about a 1" depth at edge of pot checking for moisture content.