RO/DI Tank?

My RO/DI filter came with a 4g pressurized tank. Opinions about whether this is good or bad for water quality?

 

I don't think it would matter, the tanks should be clean.

 

No cons that I know other than it is only 4 gallons. As reefers we'd want a reserve like that for a quickly needed water change. I've always kept like 15g or RO on standyby for a emergency. The tank is really for the water spigit option

AND

unless you changed things on your filter, the line that goes to the tank does not go through the DI media. It comes from the membrane the t's off. one to the tank, other to the DI. SO even though water coming from the 4g tank is clean, it hasn't gone through the DI. just a thought.

If you can afford a larger tank it would be cool. I'm thinking about it myself for my RO and for water storage during hurricane season.

I only looked at sears, other places may have a better price.
42g $160
82g $220
120g $330

 

I'm pretty sure the feed for the tank is connected to the DI output.