I would say... put the eco in the tank and a tub of water into the eco... easier to change a tub of water daily the the other way around also its easier for the frogs to get in and out of the tub of water as the tub gives a little more grip then the glass..

on a side note I see both frogs in that tank ( at least it looks that way ) not a good idea.. I keep one frog per container except for breeding and ive had accidents with just those times together.