Sounds like you're already on the right track. I've built a few fire pits myself, mostly using reclaimed materials to save some cash, and honestly, a bit of caution goes a long way. If you've got frogs chilling around your setup, that's usually nature giving you the thumbs-up—frogs are pretty sensitive critters, so they'd probably bail if something was seriously off.
But if you want to be extra sure without spending a fortune, maybe just do a quick burn test first. Light it up for an hour or two and watch how things react. Check for weird smells, smoke color changes, or residue left behind. If everything looks normal and nothing's giving off strange fumes, you're probably good to go. I did this once after worrying about some old bricks I'd used... turned out fine, but better safe than sorry.
Either way, sounds like you've done your homework. Enjoy the fire pit—nothing beats sitting around one on a chilly night.
Good advice on the frogs—I hadn't thought about that as a safety indicator. When I built mine last summer, I used some old pavers from the previous owner. I did the quick test burn too, mostly because I was paranoid about hidden chemicals or something. It smelled a bit dusty at first, but nothing weird or toxic. Been using it ever since without issues...and the frogs still show up, so I guess they're cool with it too.
Glad to hear the frogs approve, haha. I did something similar with reclaimed bricks from a neighbor's patio—didn't even think about chemicals until after the first fire. No weird smells yet, and the squirrels still raid my bird feeder nearby, so I guess we're good...
Reclaimed bricks are usually pretty safe, especially if they've been outdoors for a long time. Most chemicals or sealants tend to break down over the years, so unless you noticed something obviously off (like weird fumes or discoloration), you're probably fine. I've used reclaimed materials in a few outdoor projects myself and haven't had any issues yet.
One thing to keep an eye on is cracking or popping when they heat up—some bricks aren't meant for high temps and can fracture. Happened to me once with some old pavers I used around a fire pit... nothing dangerous, just annoying bits of brick chips scattered around afterward.
Honestly though, if wildlife like squirrels and frogs seem chill nearby, I'd take that as a good sign. Animals tend to notice problems before we do. Just keep an eye out for any changes after a few more fires, but sounds like you're good to go.
I've seen reclaimed bricks used safely plenty of times, but I'd suggest giving them a quick test run first. Like mentioned earlier:
"One thing to keep an eye on is cracking or popping when they heat up"
Just start with smaller fires initially... better safe than dealing with brick shards later.
