Algodoo

Please explain how this happened.

I had just been messing about with simple stuff like water And hadnt realised i had cloned a plane but i had made these to brown blocks and fixated them to one of the planes unknowing about the other plane and then all of a sudden the water flies out everywhere and then i thought wtf? Then i realised the second plane but still dont know what that had to do with it but after i deleted it the glitch stopped. It also works with all other objects and things can fall through it even though it has collision menu A on it? No hacked or even edited values on it like the weight and stuff. No invisible objects please please explain this to me