I have this Idea for an Auto top off / auto water changer. I was trying to think of a way to automate keeping the water lvl constant in my 600G tank and at the same time changing the water in the tank. My first idea was to run an RO/DI unit to the tank but I dont want to use one due to all the extra water used since most of the water run into an RO unit is discharged as waste water and with RO units I know it removes everything and that you need to add trace minerals to the water with addatives such as Equilibrium so I thought I could just use one of the carbon block filters from an RO unit to remove the chlorine from the water and then regulate the flow with a ball valve thats plumbed right into the house water supply and replace about 25G a day. Now to remove the water I was thinking of using an over flow similar to what I have now that takes the water from my tank to the sump but plumb it directly to the drain I already have that takes the water to a floor drain in the basement. Are there any problems with running a set up like this? Should I run a single carbon block or two? Will the carbon block even work? TIA