Really, the best thing you can do for yourself and your reef is to get an RO/DI unit.
I don't put anything in my water from the RO/DI unit except the salt. No chemicals at all. The chlorine and heavy metals are gone. It's so pure that you actually shouldn't drink it. The de ionized water could possibly strip the mucous out of your throat and GI tract.
I bought mine at this place:
Filter Direct Online Store (C)
Click on Aquariums and then find the one that suits your needs. It's not really necessary, but I would get the best you can afford.
I bought this one:
Filter Direct Online Store (C)
It's about $15 or $20 for the shipping. All the parts are there. All you need is a couple pairs of pliers, knife, crescent wrench and some teflon tape. Took all of 2hrs to hook it up.
I don't have very good water pressure in my house. This unit takes 60PSI to work properly. I ended up buying an $80 pump to hook up and boost the pressure. Still, cheaper than most of the stuff on ebay and definitely cheaper than anything even close to the quality from online retailers like FosterSmith.
I don't know if it will really do 100G per day. But it does 8 or 10 gallons a week and thats good enough. It will last for years before it needs any maintenance.
If you don't know what RO/DI is:
Reverse Osmosis
De Inonized
I don't know enough about it to explain it and my fingers are tired. :mrgreen: But, it's the best water you can put in your tank. And that is crucial to success.