Evaporation ????

[StephenA]

Losing 5 gallons a day do you ever have to do water changes? 5 out, 5 in daily seems like your water would be fresh all the time.

Yes! When water evaporates it leaves all of the solids behind in the tank. The only think that leaves the tank is H2O. Salt, CA, Fish Poop, etc. all stay in the tank water. This is why it's so important to keep you water level constant.

My 120 needs about 2 gallons a day. I'd say the MH lighting and sump cause most of the evap to happen. One of the best investments I purchased was an osmolator. I never come home to a low tank any more.

[Tim Marvin]

Yes you still need to do water exchanges to remove the dissolved solids, and build up of bad stuff.

[Tim Marvin]

Yes you still need to do water exchanges to remove the dissolved solids, and build up of bad stuff.

[GaryP]

Humidity plays a large role in evaporation. I have much less evaporation in the spring/fall when the windows are open because generally the air humidity is higher. When you are running AC or heat, the humidity is generally lower and evaporation increases. I usually have to turn on an extra set of fans when the windows are open to increase evaporation and decrease temp. Evaporation = cooling.

This is exactly why we have central AC here while they can use swamp coolers in lower humidity climates like El Paso. The humidity here is to high for effective evaporative cooling. This is generally not an issue unless you are running MH bulbs.