Well, now that you ahve this kind f volume in front of you, you should move your RO/DI production way up. In anticipation to my system, I bought a 100 GPD unit with dual DI chambers and a flush kit. Now, I find it still not making water fast enough for my taste in case of an emergency and I make about 80 gal/day from it. In about a month or so, I will get a booster pump, a second 100GPD chamber, and an adjustable flow restrictor to get about 250 GOD from it all according to reef aquarium systems. That is where I bought my original unit from and I highly recommend you talk to John there. He is awesome, and their prices are second to none.
You ahve to be able to make a large water change if you need it and your current unit is going to be running every 2-3 days just making evaporation loses depending on what size holding container you have. Trust me on this one, you need a faster unit.
Something you may want to do in the meantime is put a post in the wamas site and see if anyone has an RO/Di unit they could let you borrow for a couple of days to help speed up the process. I would lend you mine, but it is hard plumber to my system already.
Alberto