Hi all just like to share a tot with all about a cheaper way to top up water.
Well I understand from a friend who owns an aquarium shop that he don't use auto top up devices for auto top ups. What you need is to hook up your tap above your tank or sump and let the water drip. This only applies to larger tanks.
And if you are in planning stage, also plan an overflow pipe for event of flooding if the water drip is too fast for the evaperation rate.
Not to worry about chlorine and unwanted stuff from your tap water as you can run the plumbing works to a DI/RO unit before running it to the sump or tank.