Hello everyone, I agree that the most important thing is to limit the reservoir amount that a potential sump float failure could pump into the sump.
IMO the best way to solve this is to connect the RO to a garden hose timer that will only let the reservoir be filled during a specific time each week.
By doing this, you limit the reservoir amount and automate the RO to fill the reservoir once a week (or a different timeframe if you need it), that way you wont have to manually turn the RO on.
In the event of a float failure this would happen:
1. The reservoir is completely pumped into de sump. The reservoir volume calculation is critical since I think that the volume should be such that if it's completely pumped into the sump, the aquarium shouldn't suffer to a life endangering state.
2. The pump would run dry and break (at $15 who cares?)
3. At some point in the week you should notice something went wrong and fix it. In the meantime the tank is fine.
There are a couple of timers on the Home Depot website.
I would appreciate your feedback since I am going to set up an Auto Top Off soon using the Osmolator and this approach.
Thanks.