The 100 gallons per day is how much water the RO
unit can filter in 24hrs. You can make as little as an 8 oz. glass if you wanted i make about 35 gallons a week from my 75 gl. per day RO
. filter because thats what i use
Sumps, a sump is just a box with one two or three chambers 1st chamber is the intake where the dirty water from the main tank drains. This is where i like to put my skimmer some people will put a filter sock on the drain pipe i dont
2nd chamber often called the refugium or fuge This is where you will grow macro algae, pods
and other good things for your tank I put my heaters in here (as well as any probes) because the flow is a bit slower through here.
3rd chamber is the return section this is where your return pump sits it's the pump that brings the filtered water back into the main tank. This is where i like to put my ATO= auto top off. This section will show any water loss as the rest of the sump will keep the same level You want to top off with RO