Need bigger air conditioner to cool rooms/tank

[jamal-188]

I currently have a little 5,200 btu a/c in my room that isn't cutting it. It's in the mid 80's here and already I'm having heat issues especially with my 110g 2x250 mh's. I need an air conditioner to cool 2 rooms that are connected, each room is roughly 12x12, anybody know how big of an a/c unit I'll need to keep these rooms around 68-70? I"m not sure if this air conditioner isn't working or too small(thinking maybe both) but it's about 78 in my rooms with this running full time.

 

[CBRGuy]

http://www.ieionline.org/residential/hvac/calc4.htm here is a calc for BTUs. It looks like you will need about 6500 BTUs