Weird, Random Question...

[ashleyy]

I don't know where to put this because it's about a tank that never/will house a betta.. lol

But it's about my boyfriend's 55 gallon tank that just housed a pirana and a pleco at the time.
I never got to witness this because it happened before we were dating.. but he said that it foamed up and "salted" over. Foam came out of the tank and onto the walls and everything. Then when it dried it turned into "salt" You can still see some residue on the wall behind the tank that we can't reach and it looks like a salty substance ran down the wall....

What happpened?!?! lol what made it foam "salty" stuff. lol

I tried googling it and all I got of course was about marine tanks. lol