sponge filter question

i am having a problem with my sponge filters in any tank deeper then 16 inches..... when i drop the filter in the air stops coming out but if i sit on top of a clay pot and lift it up to about the middle of the tank it operates just fine can someone help

Sounds like you need a bigger pump. I have the same problem in some of my lower tanks.

Yup your air pump isn't strong enough. Once you get the one from me you wont have that issue any more.