First thing to point out is that 82ºF is not "too high" and I might choose not to do a darned thing if this were my tank (which ran at 82.5-83.5 for 3 years and grew SPS corals like crazy). If you like the sound of this, forget about all our advice and go back to what you were doing.
Second, if you really can't live with 82º, are you really running super-nice LED lights on top and Thomas Edison-era
incandescent over the refugium as someone else mentioned??? Personally, I would shut down the refugium altogether and save yourself the immediate bother - from pictures it doesn't appear you have any reason for it (fish load) as of this time. Reactivate it when appropriate lights (CFL, LED...really no reason for other than LED) are available to you and you have a real need to have the refugium online.
Dave, I've got to disagree with you, I've been running a Mag 9.5 for two years and I have MH and 4 T5's and my 120 runs at 75-76 without a heater. I do have a small fan that blows across the top of my MH fixture.
Agreed.
Mag's are extremely durable, reasonably priced pumps - they carry more watts because they have stronger (larger) motors. Quiet One is a high-quality, reasonably priced, more-efficeient pump and what I run in lieu of Mag's when a tank is over-loaded with heat. Trading off for lower power is not a one-way trade (or...yes, that extra power is actually used for something!)...smaller motors mean higher likelihood of non-starts due to debris IME. Some kind of mechanical prefiltering for the pump's intake is recommended in this scenario. (Which becomes a weekly maintenance item.)
Yep! Blame Rob! I've got a sneaking suspicion that the ventilation around the tank is as much to blame as anything. I think a simple desktop fan circulating air around the tank would fix the problem. It's not like the tank is getting 90* or anything. A couple degrees shouldn't be too hard to drop.
It's possible that with the seasonal weather changing the tank is running also running a few degrees higher than it otherwise would due to the HVAC not running consistently like it would in the hot or cold months. Humidity and heat both build up in the room causing heat to build up in the tank. You're right that a fan might help - even just something simple like a box fan running in the room may even help.
It also looks like the water surface in the tank is dead-still. Doing something with a powerhead to disturb the water surface 24/7 will actually have a decent impact on tank temp as well due to increased evaporation.
I agree that external pumps will be cooler than internal. But with my mad scientist approach to plumbing the sump I do not feel that my setup can be modified for one. Refugium light is back off now cause the temp climbed up to 82 degrees. Tomorrow I seek a fan.
In your situation, an external pump actually wouldn't be much different - all the heat would still be under the stand to be absorbed into the tank above.
It also looks like the water surface in the tank is dead-still. Doing something with a powerhead to disturb the water surface 24/7 will actually have a decent impact on tank temp as well due to increased evaporation.
Since the tank stand is a cabinet in the corner and is totally wrapped with sheet rock. This is my new idea: I'm thinking of cutting a hole through the wall(into the garage or under the stairs) using like a dryer vent tube and have a fan on it to pull heat out of it. Bad thing of using the cabinet like I did , which is a permanent bar , I never even considered it storing heat the way it does. The doors on the front are the only ventilation.
As has been pointed out, I would just decommission the refugium for now. If there really is an incandescent bulb in that light, replacing it with a ~5500K LED lamp should make a large difference in your heat situation.
If you really must proceed, one fan pushing room air (cooler air is near the floor) into the stand may be fully sufficient....possibly another fan to pull hot air out of the stand (hotter air will be at the top of the stand) would be needed too.
If you decide to do any venting as you described, I would advise to use smooth, hard vent pipe vs the flexible foil-looking stuff....catches less dust and flow is better.
-Matt
