I would NEVER run anything straight to the tank that has the potential, through failure other than my own, to not only flood my house but in so doing, kill all the life in the tank as well which is exactly what will happen if (when) a float valve sticks allowing straight RO/DI to go into the tank unchecked. At least with some sort of reservoir you can limit the damage.
Guilty as charged, don't do that folks.
I have a separate 15 gallon glass aquarium that I keep filled with RO/DI with a Tunze osmolator on the reef setup, but a float in the sump on the 240 FOWLR directly to the RO/DI. >Don't do that.< :wave: