Stevew420, are you still having problems with smelly reservoir water?
First...if your reservoir smells unpleasant to you, then you might have Anaerobic bacteria which are the bad type (for the most part). Aerobic bacteria, the good guys, enjoy highly oxygenated water. So, my first easy suggestion would be to add more oxygen to your reservoir. (btw- 1watt/gallon is my minimum recommendation for an air pump.) The beneficial bacteria, the aerobic guys, usually make your reservoir smell like compost tea or kinda earthy, but not sour or rotting...if you ever smell something rotting, get rid of it, that's a sign of anaerobic bacteria.
What sort of additives do you put in? Any sort of 'zymes? Items like Hygrozyme break down organic material into stuff that the bacteria can eat. While the bacteria do this on their own, the 'zymes speed this process up. Zymes are great so as long as you don't have the bad bacteria thriving off of the food they produce, naturally you would want beneficials to be eating the food you're producing for them since they eat the same foods as the bad bacteria. In sum, on the 'zymes, you'll want want to avoid using them until you know for sure that you don't have bad bacteria in your reservoir.
Are you knowingly adding any beneficial bacteria like sub culture b/m, aqua shield, or rhizotonic? Sub Cultures b/m and Aquashield go very well together to create a diverse set of beneficial bacteria. I actually have been brewing my own tea for some time now.
This is one of the best posts in the entire Rollitup.org forum, it may take you an hour but if you read the whole thing I'm confident the solution to your problem is in there. Most everything I'm saying will go along with what's in that post.
But really you have two options as to what you can do...you can either attempt to go for the sterilization route, which entails the thorough cleaning and a crossing of the fingers while you hope you killed all the living bacteria, fungi, virii, etc etc. That's your first option...I did attempt this strategy that for a long time, spent a lot of money on H202, 91% isopropyl, bleach, Physan 20, etc etc.
I currently use the tea concept now of breeding my own beneficials. In this approach, you still want to do your best to sterilize everything. I use a combination of a strong h202+Physan 20 solution and soak stuff for 24 hours if possible including all pumps, airstones, tubing, spray heads and any non-scientific testing equipment. After you feel confident everything is sterile, be sure to rinse thoroughly too...any residual Physan 20 or whatever you decide to use could keep the benies from thriving.