Best way to deal with extra humidity

You can run the bath and kitchen exhaust fans if they actually vent outside. It does help but I finally bought a larger dehumidifier last week.

 

did u have a previous spill or leak?  cant see a 40g causing that much humidity to create mold unless there was the before mentioned but it could be possible. is there a humidifier on your furnace that could  be adding  humidity? i wouldnt think youed have a problem in the winter months with humidity just the rest of the year. i would install an exhaust fan either thru window, thru wall or thru roof in that room other than that the only other option would be the elec. hog. exhaust fan would be cheap and you wouldn't have to scrap the build

 

We installed an air to air heat exchanger that we run in the winter. We pick up the air that we want to get out of the house in the room where we have the DT. It gives us fresher air in the whole house in the winter and keeps the humidity down in the room with the DT.

 

I hear ya on the electrical costs with the dehu. I started running lids on everything from sump to dt to refuge. I second what xmasia said about the exhaust fan, they are much cheaper to run and I have mine on a timer. I would love to have an air exchanger like iaJim but its a little to pricey for me to justify to the wifey for fish tanks. Good Luck and on with the 120!

 

I have this problem big time in the winter. Condensation is the problem. The water in the air hits a cold surface (wall, window, metal can lights).

I use screens on my DT in the summer because the AC takes care of the humidity. I use glass tops on my DT in the winter.

In my basement I made acrylic lids for all my sump/frag tank. The only opening I have is a 2' x 2' are in the sump where the return lines drop.

Lids are your easiest answer my friend. Start there and see what happens.

 

This thread on RC in the Neptune Systems forum talks a little about using an Apex to control an exhaust fan based on either high temps or high humidity. A humidistat is hooked to the Apex using the breakout box. I would imagine the exhaust fan is hooked to an outlet on a controllable outlet. Programming included.
That being said, sounds like Jim's point about using lids is probably the least complex.  The things that I would be concerned about with that is oxygen exchange and the possibility of the lids holding the heat in and not properly letting the water in the sump cool.  Oxygenation of the water is probably handled by the skimmer injecting all the air into the water (assuming the air intake is outside of the lids) and Jim has a basement sump, so it's likely in his case, heat is not an issue, but may be for those that have an in-stand sump. 
--AJ