ya those cheaper regulators have needle valve issues, exactly what happening to you. what i would do is replace it with an Ideal or swagelok metering valve thay are rock solid. also replacing them are pretty easy, just have to find the right size needle valve/metering valve.
edit: also talk to Orlando at Greenleaf he might be able to sell you one or SUMO, might be able to too. also i know Rex has them for sale on his site.
I just set up a 140 gallon freshwater in the front office at my business(craiglist-$140.00) and i have had tons of great feedback. setting up any tank in your business is an awsome idea, cant wait to see pics when its done.