Plenum poision?

[Titus07]

Is it possible that if something were to burrow in to the plenum, that water could seep out and poison the tank?

 

[polyppetey]

Thats why you have to cover the plenum with screening.
Also add 1-2 inches sand then cover it with another piece of screen, top it off with the rest of your sand, that should keep the critters out.