You can mount the DI
unit upright the problem is those smaller DI
units just dont last as long and they are far less efficient than a true vertical 10" unit as seen on the filtersguys RO
unit 3rd from the top. DI
binds to the final TDS
left in your water after the RO
membrane. It litterally gets used up. The small units are subject to whats know as surge TDS
. as it approaches the end of its life the TDS
reading can go from 1-2 to 50-60 in just a few gallons of water.
As with everything with this hobby if you opt to buy quality products that will last you and your reef will be much happier in the long run.