I live in FL.also.Run your air all day which if you live here I'm sure you do.I don't mean run it non stop,set the thermostat to 78 degrees or whatever you like.Whatever you use for substrate make sure it's completely dry,they don't need water so there won't be that little extra humidity.With a basking temp.of 120-130 degrees,warm end ambient temp.of 100 degrees and cool end ambient temp of 85 degrees this along with the air cond.should knock it down low.I have my thermostat set at 78 degrees during the day and 77 degrees at night so my humidity in Oz's cage is about 5 percent during the day and 30-35 percent at night.I have even had to bury a little square of repti carpet under the playsand to wet with water and re-cover with the sand to get some humidity during the day.But I wouldn't recommend this for you since it's high already.So I honestly don't think it'll be a problem for you.
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Cajit
1.0 Mali Uromastyx (OZ) Doug Dix