Humidity problems for large tank

[hawk]

I have one problem in my fishroom you may or may not need to consider. Tank is 375g, total water volume around 600g. The room is pretty airtight with 2 exhaust fans and fresh air intakes. The fishroom ceiling is a drop with a lot of copper plumbing for upstairs kitchen, bath etc within it. In the fishroom I have a sink and rodi. The room can get upto 84-85 degrees. The rest of the basement stays cool. Now the problem... When the rodi is running for several hours at a time and the relative humidity is high like now, the copper run to the rodi in the drop ceiling (sealed tight from the fishroom) sweats and drips condensation. When I first noticed it I used insulating foam tubes on the pipes. This helped but not totally. What I think is happening is the area above the fishroom is warm, the cold water running through the copper meets that warmth causing the condensation. If I were to do it again I would change the copper around the fishroom to pex, which I'm told does not sweat.