Calling all reefers with basement aquariums!!

[Scythanith]

I have an enclosed fishroom with a 270g tank and two ~40g sumps. There is a ~4" forced air return and a 6" HRV exhaust for that room alone. My humidity logging shows me the room is at 25.3C and 38.3% RH right now. I have seen it get to 45% in the summer. I have green board for all the drywall as well as a floor drain.

In your case I'd devise an HRV vent drawing from the canopy and the sump area. I have also heard of people saying their HRV's have rusted but mine hasn't shown any sign of rust in 2 years so take that for what it's worth to you.

Cheers,
Scott