reptitherm "mini" UTH -- enough heat for leos?

Hi, I just got 6 "Visionarium" tanks and want to use undertank heaters. The only ones that fit (due to "ribbing" around the edges of the plastic bottom of the tanks) are the reptitherm minis (4 watts), which is what the tank manufacturer recommends. They said this will put out plenty of heat for leos. Is this really enough? The tanks are approximately 12x30x12 and have glass sides, with a heavy-duty plastic bottom. Zoo-med says the minis will raise the temp of the tank "5-10 degrees above room temperature," which would only be 75-80 degrees in a normal room. Is that accurate or do they run hotter? Should I try to squeeze in a Reptitherm small (8 watts)? Or will the minis be OK? The tanks will be stacked, if that helps, and will be attached to a Helix controller.
Thanks in advance for any advice!
Jax

I used to keep my leos at 80 degrees daytime temps year 'round without problems. 75 as a nighttime drop would be ok too... If you have the capability of 2 mini's per cage (side by side) I think you would be better off than going with one thats too big, especially if thats what Vision recommends.

I agree - it depends on the ambient temp of your room. My room flux's in the low 80's also. I use mini's on all of my glass tanks - and have for years.

Originally Posted by princesskain

I agree - it depends on the ambient temp of your room. My room flux's in the low 80's also. I use mini's on all of my glass tanks - and have for years.

Do you mean the ambient temp in the room is in the 80s? Or in the tank? I can't really keep the general room temp higher than low 70s -- would the mini be enough to raise the substrate temp to the 80s? And is that enough? I've seen care sheets that say the hot end must be anywhere from 88-95. Would it help to use a slate or ceramic tile over the heater, instead of carpet?
Thanks for your help!