Thanks for the replies,
In my setup i would rather use some mechanical controller to water level rather than an electrical one, as i'm afraid even my reservoire would get empty sometimes. what i'm considering is having a big sump that would hold around 20-30 gallons of water in the return partition. The top off reservoir will be higher than the sump and water will flow by gravity and will be blocked by the mechanical floating ball type.My problem is that this tank will be in my house in Dubai where it is extreemly hot in the summer, also I travel very frequently for 5 days most of the time 2-3 times a month. so I don't want to risk burning a pump if the top off gets empty. so basically the top off would delay water starting to go down in the sump and when it gets empty then water levels in the sump would start going down.
Anyone from my family could pass to my house and fill the topoff if my stay is for more than 10 days.
Is the electrical system safer than the mechanical one?Please indicate if it's safer or better to have the electrical one? although i believe that in my setup the mechanical one should be safer. please post pics of valves you are using and share good and bad experiences you had with what you're using.