I think the most important thing to container gardening is right size pot for the right flower or plant. Right location and remember they dry out faster in pots then in the ground so water water water:)And always have good drainage. Holes in the bottom of pots:)
Container gardening is my biggest challenge. I just can't seem to get the watering right. Last year I bought an Earthbox system to grow tomatoes and it worked the best of any of the containers with reservoirs I have. I had another container that was supposed to be used inside and that worked ok, but the plant ended up sending all it's roots into the reservoir and so it wouldn't hold any more water...
I have been doing container Gardening for 7 years had some problems along the way but did pretty good with my containers. I don't know much about water reservoirs but if it works stick with it. Other then that all I do is keep a watch on the weather and go by that and just take my finger and check deep down in the soil to see if its dry and I water. I have to only water about once in the summer in the morning or evening. If its really hot I do twice. sorry could not be more help with the reservoirs. I always let the water drain out the bottom and I don't stop till I see it drain out the bottom