What size dehumidifier for sealed room?

Hey! I want to use a dehumidifier only at night. The humidity in the day is fine. The room is 10x10 ft. Want to get relative humidity to about 50%in the last 4 weeks of flower to prevent rot. Thanks!

http://www.ebay.co.uk/itm/ECOAIR-ESSENTIAL-PORTABLE-DEHUMIDIFIER-MAX-12L-DAY-MOISTURE-DAMP-REMOVER-LAUNDRY-/281903274130?hash=item41a2be9892:g:Mn8AAOSwaA5Wji0P

There is not a big difference in price between the common 30-70 pint units... (Sears.com) ... I couple of things to think of.. make sure it at least has a hose drain options, you dont want to be emptying the units pan all the time... some come with a pump options that is good if you need to drain above the height of the unit. Also if your putting it on a timer, make sure it holds the settings during the power off mode.... sears used to carry one with a manual on/off which was great for timer use.. but not seen that in a while...