Hello! An Introduction & Requesting Some Advice

[Bogertophis]

The use of a thermostat to control heating devices is truly essential because snakes* don't always know enough to move away in time from excessive heat. (*especially BPs, because they require more warmth but are also heavy-bodied snakes- by the time it dawns on them that part of their body is too hot, they can have a thermal burn, or they can sustain irreversible nerve damage if it continues)

You always want to measure the surface temperatures where the snake may touch- it's best to assume your snake WILL push the substrate away & be in contact right over a UTH also. (UTH = "under tank heat") Yes, it's time to make friends with a "temp. gun" & t-stats. Your sensor just to measure ambient air temperature is fine, but you need to know the surface temps. for safety. And probes from a thermostat don't belong inside the tank because sooner or later, your snake will dislodge them or splash water on them, making the reading unreliable (dangerous surface heat can result!). The probe should be sandwiched outside, underneath- between the glass & the heat pad (aka UTH)- then, you need to verify what heat is being produced INSIDE, over the UTH with your temp. gun- where the snake can contact. Never assume that whatever the t-stat is set to is what you have inside the enclosure- use that temp. gun & keep using it for as long as it takes for the readings to stabilize. See?

About that heat pad- it's outside (under) the terrarium, right? Never inside where contact with water will happen & a shock will result- I'm just making sure, since you asked. As you've discovered, it takes a while for heat from UTH to penetrate & raise the temperatures inside your set-up. It takes days, actually, for all the substrate & furnishings to gradually warm up- that's why we advise that you set up a new home for a snake (with all the "trimmings") for at least a week while controlled by a thermostat, before a snake moves in, for safety. Otherwise, if this is rushed (as is very common, let's be honest- we've all "been there"- excited to welcome our new pets) -if this is rushed, & you're not using a thermostat, or using it incorrectly (where the probe is matters greatly), you can end up with excessive (ie. dangerous) surface temperatures for your snake, including inside their hides where a shy new snake is most likely to want to be.

As far as adding water over the UTH- you'll be trickling it in so it absorbs into the substrate- that will slow it down anyway- so yes, it should be safe for the glass. (Glass is normally tempered glass, & assuming it's not greatly overheated anyway, it's just fine.) I've been using glass tanks with UTH for decades & never cracked one yet.

Humid hide: What many of us do is use a large plastic food container (the kind with snap on lids) with an entry hole cut into the top. Put soaked & drained moss into it- about half full so there's room for your snake too- & put the lid on. You can either "show your snake the door" (so to speak) or let him find it on his own. When snakes feel safe to move around more (often at night, when you're not looking), their nose will lead them to that wonderful aroma of fresh moist moss & you'll find him in there- snakes love this stuff, even when they're not in shed. Granted, the container isn't so pretty- if that bothers you, you'll find ways to camouflage it- but you'll have a happy snake. They seek hides that make them feel safe & snug- not too high or "open", only one door (not too big)- & they like "back pressure" so they know a predator can't sneak up on them. If hides are initially too big (with room to grow into them) you can always wad up a paper towel (etc.) to take up some of the extra space inside it & make it feel cozy to your pet.

Pet stores sell lots of cool looking decor (skulls are very popular) & since it makes them money, they probably always will. But skulls & "castles" (etc) are best used for tropical fish- they don't get stuck. I discovered that some of those things even have very sharp unfinished edges left inside, so if a snake instinctively snugs into one, they can get cut up- and I KNOW you don't want that.

With snake-keeping- get used to taking temperatures. Remember that we're about 98* so water or surfaces don't feel warm to us until they're OVER that, which is too hot for your snake. See? Ya gotta use that temp gun & consider what your snake is experiencing. This all gets easier with practice- if anything doesn't make sense, just ask.