with the cost and availability of the kent float valve under $20. It's not worth your time and effort to track down those parts.
If is very reliable providing your sump is not acting as dual purpose refugium where snails could get caught and stick in the on.
Good thing about these if the valve does stick it is usually because the line gets clogs ( most likely when using with Kalk ). Should remove and clean with vinegar as preventative maintenance every few months. Using with FW should require even less.
As for your top off water. Best to avoid a endless water supply regardless of top-off method. This would include hooking it straight up to your RO/DI unit. It's nice that you don't have to find room for the top off container this way but you are at risk of greating a FW tank in the case the plumbing or tank is leaking or if using a
siphon overflow ( god forbid ) that fails, or an overflow clog it could be disasterous. That's the main concern with this method.
The con to this method is your top off water needs to be above your sump or above your tank ( if you don't have a sump ). If you have a fish room or don't mind the bucket visable, this is a good high reliablity option.
