Sorry Y that was supposed to read 180 +gallon in wall monster. I meant it aint the huge tank, but its looking very nice in its cabinet.
For fans I have 4" industrial grade fans that I recover from oxygen generating machines, they move a lot of air. I have seen people run 4" dryer duct to fans in the ceiling or duct to outside, tho I don't think thats very practical in your case
The biggest probl.em you are facing is trapped heat in the cabinet, the more heat you can let escape of force out the less it affects the outcome(tank temp).
FWIW and Realize thats a nice cabinet you got, but if it were I , I might consider replacing the top of the cabinet with a piece that went with the look but was basically open and covered in nylon screening or eggcrate lighting grid. Then mayby 4" below the open top I would have a pair of 4" fans suspended by a clever bungee cord type affair, to cut vibration induced noise.
Also the other thing you may run into with sump below is salt creep all over, increasing the airflow in the sump area will help evaporative cooling unless the AC doesnt work and you have a high humidity situation.
Hopefully using the guidelines I have outlined you can keep temps managable and not have to add a chiller

If you are intersted in a couple fans, I get them free from work and am willing to share. I will happily ship to a neutral work address or whatever. Email ShirleyM, I sent her some last year. Good Luck, and have fun
