Ro/di top off help

[Travis8896]

I am helping a friend redo their saltwater aquarium and will likely be performing the monthly maintenance on the tank for them as well. In the process of going through the setup I found the rodi unit is hooked up straight to the tank and is constantly cycling water and wasting resin. This is obviously no good and needs changed immediately.

180g tank with 30g sump

What i need help with is finding the best solution and how to set it up?

I'm currently leaning towards a water change station with 2 containers one for freshwater for top off and one to mix salt for water changes. But unsure of best design

 

[threebuoys]

My setup had a small reservoir which hold maybe a couple of gallons. It was part of the RO/DI package I purchased. Then the line from the reservoir feed my saltwater mixing tank through a float valve that prevents the mixing tank from overflowing. I also have a line feeding an RO/DI 30 gallon brute from which I take water to my aquarium ATO reservoir. Works well.

The location of my RO/DI system prevents me from running a line directly from the ro/di equipment to the display tank. I imagine that would work fine. My tank is 125 gallon. I suspect those with larger tanks are more likely to have a direct hookup. I use about 5 or 6 gallons of ro/di a week, so a direct hookup would not be a big improvement for me.