Looking for help from AZ reefers

not worried about mold. My issue is making the house feel cooler. Less humidity in the house makes it feel cooler inside, most A/C units pull enough moisture out to drop the humidity below outside ambient air. However with us having low humidity outside, and high inside it does not "feel" as cool in here as it would if I had a lower humidity level. I might be chasing my tail here though

 

A lid would slow down evap, but would also raise temp in the tank. You may counter the increase by using an external return and moving electrical outside of the cabinet. Once there's a lid, you could try dehumidifier again.

 

I found the best thing I ever did was switch from MH and VHO lighting which required either a chiller or multiple fans to keep the temperature in check to LED lighting which does not require any supplemental cooling. Both the humidity and the evaporation dropped considerably.

 

I switched to LED years ago, but 20% more humidity in the house than outside seems odd. What are we talking about when you say external return? My system drains via a durso into the sump, and is then pumped back up through pipe and through a direction changer, then back into the tank via 4 nozzles.

 

An external return pump has part (transformer?) outside of the water. The heat is transferred to the air instead of the water. I believe that the sump would need to be drilled. Not sure how much that would reduce the water temp, but anything helps. Supposed to use less energy too.

 

got ya, yea my whole pump is outside the sump, its not a submerged pump

 

Some external pumps run very hot and still transfer heat to the water.

Lowering humidity in the house is tough without a dehumidifier. If you vent the tank stand or canopy to the outside you, at least in theory create a vacuum or low pressure area in the house so hot outside air creeps in through cracks, wndows and doors to replace it. In Yuma (I lived in Yuma from 1968 thru 1971) or here in Phoenix thats not good in the summer. With todays modern houses sealed up so tight to be enery efficient its hard to vent outside though as there is no route for outside air to replace it.