Well, you can always tape over some of the holes from the outside to help the humidity. How cool is the room where the tub is? If the ambient temp is in the 70's, most smaller UTH with have a really hard time keeping the temps in the proper range, that's why I tell a lot of people who are having that problem to use a room heater if they can, it can make a huge difference. The water bowl is really too big for that tub, and while lots of water can be good for humidity, it can make heating things up even harder.
If a room heater is not an option for you, you can look into a slightly larger UTH, or if necessary a CHE to place in a light dome and place over the tub. You won't want it to sit on the tub obviously, but they make little stands you can use to keep it 8 inches or so away and that may also help. It is important that the probe is resting on the bottom of the tub itself to get an accurate temp reading. You may need to increase the temp on your UTH by a few degrees and let it sit overnight then check it again in the morning. It can take a few days of trial and error to get things right, especially if it's your first time setting up a tub. Once you get one right, the next one will be easier.
Gale
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