Okay, my tropicals tank is running for years now, and its heavily planted. There hasn't been a snail in there in ages, no new plants for at least the last 6-8 months, and even after that no snail hitched a ride on those new plants.
Now, all of a sudden, snails are popping up in that tank, and munching down mostly my anacharis!! Where are those guys coming from? Of course, just ordinary pest snails, and I pick them out as I see them. But still, they seem to have come out of the blue...
Isn't that the strangest?

If you have snails elsewhere could they have been accidently transferred via a bucket, net, siphon or other equipment?

Fishmerised said what I was thinking...

If that is not the case, that is very weird!

Maybe the snail fairy came. Did you leave any pockets of slime under your pillow?

... I can't think of anywhere else they could have come from. The inter-tank transfer theory sounds better than anything I've got.

Well, it couldn't have been the nets - I haven't used any in the tropicals tank in ages. The last time was about 8 months ago, when I tried unsuccessfully to get the algae eater out of there.
Syphon? Hm, the only other place where I have pest snails in the tank is the planted goldie tank in the bedroom. The syphon is 25 ft long, and I usually rins it out with either bleach or PP after I am done with water changes. That really could be the only explanation, if the bleach/PP didn't kill the snails. Which is hard to believe, since there is always water residue sitting around inside the python....

Hmm, that's odd, have you done anything to your tank recently? Rearranged things, changed anything?

Have you recently added any new fish to the tank? I have seen snails hitch a ride in bags with fish (and have done it myself by accident before). Once I found a snail in my 100 gallon which was very weird because I hadnt added anything new to it, and I sterilized all my plants very carefully before going in. I had other snaily tanks but this snail was something I hadnt had anywhere else. To this day I dont know where it came from!

Nope, no new fish, nothing new - I haven't had time lately to get around looking for fish. The last purchase was a female betta last winter, that was all.
I think it might have been the python...