Getting humidity up and staying constant

[Sarosaurus]

Hey folks!

I have recently set up a small Exo-Terra Terrarium with a White's Tree Frog in it where I work. It's 12"x12"x18" as it is a small frog (I will tell the customer that s/he will need a bigger tank when the little thing gets larger). I am having one hell of a time keeping the humidity up. When I first set up the tank, the humidity had been around 60%, but when I have come in every day since the initial set up, the humidity has dropped to 20-30%. At this point, I have it up to 40%, but it's not getting any higher. The substrate (sphagnum and fir) is pretty wet and there's a 75 watt bulb keeping the temperature at 80 degrees (ambient temperature).

What can I do to get the humidity up? I have tried blocking off the top with towels, cardboard, and a plastic piece from a display we had. Nothing is working.

Should I up the wattage of the bulb? The fixture can hold up to 100 watt bulb.

[Mentat]

An office environment during Winter can be a very dry one. Had good results blocking tops with "plastic wrap" used to wrap food items with. Just cover whole screen area that is not below lamp and affix with small pieces of tape to screen top edges. Normally, find it easier to cover whole top and then do a cut-out for lamp.

If that still does not do it; you might need to adapt a nozzle type humidifier to your cage or get one of those made for vivariums. Using higher wattage lamp will raise habitat temperature accordingly. Need to watch that too and avoid overheating frog.

[Sarosaurus]

Well, we aren't in an office, but in a pet store. ^.^ But it's cool in here...even with the heat on. We might have to have some plexi-glass cut to fit the top part of the tank. =]

[Shanny]

That high of a bulb sucks all that moisture out, especially in that small of a tank. I have an 18x18x24 and only have a small 2.0 UVB and a 50 watt red heat bulb in mine and that keeps the temp anywhere from 73-78 degrees F. My humidity stays around 40% and goes up because I have a home made fogger on a timer that goes off every couple of hours for about 15minutes.
I made the mistake of having a 75watt in my tank just recently because it's winter in Minnesota and it gets cold here.. So I thot I needed it, but it's too hot for frogs, it's more for reptiles who like that dry heat

[mim]

iv got a polystyrene sheet on the back of my heat mat to stop the heat escaping. i sometimes get the same problem, either cover the top as already suggested, mist more often if possible. i found that once i put moss in it really bumped up the humidity. doesnt having live plants help also?

[helm96]

I added a small water feature to my 18x18x24 and it made a huge difference. I have all live plants, although I am reconsidering this as my whites get bigger and are starting to bring down the house with their acrobatic jumps! My humidity stays around 65-75% consistantly and I very rarely have mist to keep it there, except when when I decide to mist down one of my whites that seems to love the misting!