[somewhatshocked]

I would have seen the snails coming in.

You would think. But it happens to the best of us no matter the circumstances.

Anybody have any ideas how these guys came in undetected (I scrutinized every plant carefully), survived predation by 15 loaches for so long, and are just now coming to my notice?

Bebe (Moira Rose voice) MTS are so tiny they'd be able to easily hide inside the fold or roots of a plant without being noticed. Same color as most roots, even. I'm only 40 and consider myself to have pretty good (corrected) vision and a lot of experience with them. They almost always slip by.

In this case, since you're using substrate products that won't break down easily and can sometimes be prone to compaction, I think MTS may be a great addition. They'll help keep things aerated a bit. And you likely won't see much of them because they're nocturnal.

Story time: I had to move around a lot for a few years due to work safety - what I lovingly refer to as the Death Threat Era. Moved to Charlotte in mid-2013 and then moved back from Charlotte later that same year. With an entire tank room in a Uhaul. Fun stuff, indeed. Ended up doing something I regretted quite a bit for a number of years but life gets in the way, blah blah blah, insert excuse. I left a 10gal tank with plants (anubias, mosses, crypts, all kinds of stuff) sealed up and packed in storage. Just didn't have the room or desire to deal with it. Until this year. Drained, of course, just substrate - a mixture of dark pool filter sand, plants and as much of the water removed as possible. That sat in my various storage spots all those years. When I finally unboxed it to clean things up and put the tank to use? There were living Malaysian Trumpet Snails. About a dozen of them. So I'm pretty sure they can live through nearly anything.

 

[somewhatshocked]

didn't turn into a mold/fungus nightmare!

Oh, no. It was disgusting.

Rinsed all the sand, though, and it's as good as new.

 

[somewhatshocked]

I fished one of the Trumpet snails out of the main tank and plunked it into the quarantine tank in hopes I will get lots of new snails. I understand MTS are parthenogenic so I needn't worry about male/female pairings.

Anybody know how quickly these guys reproduce? Temp 78F, lots of algae and plants, plenty of decomposing plant leaves to eat .

You'll likely need to supplement feeding in order to speed up reproduction. Probably best to start with more than one in case one is near the end of its reproductive phase. They also reproduce more quickly when there are others with which to breed. While that's obviously not necessary, I've found they reproduce faster when breeding than when left to their own reproductive devices. (Contrary to what some of the newbie websites suggest.)

There's not actually a common speed at which they reproduce. Some have one brood (the eggs actually hatch inside the mother, so they're not exactly born, as some newbie sites also suggest) in their lifespan and others have multiples.

There also seems to be a belief among the newbie sites - really should call them plagiarist sites, as they constantly steal content and imagery from users on forums like this - that they only live about a year. I've had them live nearly three years and produce as many as 7 or 8 broods of 20-100 bebes.