New tank design

[Boomboy]

you didnt answer my question, what is the second hole for???

[karazy]

woops! sorry boomboy.

the reason i have two holes for my drain is because one is a emergency drain.
that way if a snail or something every got stuck up in the main standpipe(which is shorter BTW) the water level would start rising, and then it goes down the emergency drain so that the tank doesn't overflow.