RO or DI or Both

[fkshiu]

DI only is fine for a smaller tank (i.e. <50 gallons or so) in the GVRD because our TDS is so freaking low (~10!).

Larger tanks tend to require more water than DI-only units like the AP Tapwater Filter can easily produce. I used an AP Tapwater Filter for several years on my 46-gallon.

However, if you plan on sticking to this hobby in the long run an investment in a full RO/DI unit is a good idea.