35 gallons per day is REALLY slow. It will take you forever to make water with that. And both of those systems are only RO units -- they do not contain the DI stage. You definitely want an RODI unit, not just RO.
Check out these sites for some better alternatives, price wise and quality wise:
I would look for something that is at least 75 gpd, with at least 4 stages, including a DI stage. You can find something like that in the $130+ range at the sites I listed above, so a much better value than what Marine Depot is selling.
Because I was thinking I don't need all that water at once. I can make a little each day and by the end of the week I can have enough water to do a pretty good sized water change.
No, around $140. But getting a 2 or 3 stage RO unit that doesn't include a DI stage isn't going to be very effective. The water quality won't be great.
And you might not need all that water at once, but believe me, when you are sitting and waiting for a bucket to fill, you will be grateful you didn't go with a 35gpd one!
Seriously, just save yourself a little bit more and get a 75gpd one. I've spent so much money on stuff just to 'get by' and I've regretted every single purchase; ou just end up spending more in the end.
I got a purewaterclub.com 50 GPD 5 stage ro/di system that is doing well. I'm pretty much getting the 3:1 as they advertise so far. My water goes from 170-0 without any issues. Make sure and pick up an inline TDS meter as well.