Not QUITE sure what you're asking. It seems like you're saying you want to use a reservoir without a controller? Like just top up your res by hand??
ABSOLUTELY NOT!!...of COURSE you can.
14gal res doesn't sound like a lot though. I'd go bigger..especially if you don't have a chiller. I have 4 plants in 5gal pails and I don't know what size my res is but...I'm in week 2 of flower and they use OVER a gallon per day EACH. I have to add 5 gallons per day. No I don't have a leak.
So..if you have 10 pots/plants/totes/pails...whatever...you're gonna be going through 14 gallons a day if your plants are trees and healthy and your RH is pretty low.
Seriously..if you've never done RDWC, get ready to be blown away.
If there's any way you can, I'd use a bigger res. I'd use bigger buckets for the plant sites too though...which I WILL do when I add another 4 "pod" system to my room in a little over 2 weeks. I just hope these ones in the fives don't plug everything up..which I'm pretty sure they will.
ANYWAY...a bigger res will NOT hurt you. If it's too big you'll have to top up less, have cooler solution, more stability of pH and TDS....BUT...it can be a bit wasteful..if say..after 2 weeks of flower you need to change nutes to a more aggressive P&K formula you could still have a lot of useful nutes in your system that you have to dump.
There IS a formula or rule of thumb I'm sure that tells you how big your res is compared to the volume in your system. Maybe search "RDWC res size" ??
I hope some of that made sense.
