Top Off DIY

[Gizmo]

I know there have been lots of topoff ideas using a premixed bucket yadda yadda.

what I was thinking of doing (as per the pic) was to use a solenoid to control the RO/DI Directly to fill the sump back up as per a float switch. Before the items get brought up, Temp of water going in: Yes it will not be @ tank temp, however, since it is such a small amount at any given time, the heaters (and other heat donating equipment) will compensate for that. Salt? Not needed, since this is just a top off, not a sol'n for water changes. Let me know what you think or let me know if I'm off my rocker.
G