no point in going di only if your water area is hard with a high tds reading.
need to find out your tds reading first mate.
got a tds meter??
basically di only is simple.
outside tap - bit of hose to a di canister full of resin - hose to van tank.
No TDS meter ( time to buy one me thinks )
The DI system sounds great.
What would be the upper TDS reading for DI to work?
Looking at the area on your profile I'm pretty sure that di only won't cut it. di is the fastest way to produce pure but it's also pretty expensive, if your going to be producing hundreds of litres a day then a bag of resin may only last a week or two.
The best bet is to either get a different ro or put a booster pump on it, or get a better ro with a pump. Depending where you got your set up from you should already have a di vessel in the system some where. If you post up a bit more info about the system you've got I'm sure that some more advice will come.
Many of us have ro's that produce over 200 litres an hour which is a lot more than a dribble.
Simon.