Let me preface this by proclaiming my ignorance and lack of experience.
That said, and reiterated,
I have read that occasional watering from the top, or flooding of the pot by using an oversize saucer and filling it up, can help the plants by oxygenating the soil and preventing anaerobic bacteria and mold from taking hold.
I've solved this and other problems for myself by putting the little monsters outside for the summer, where they seem to like it best.
Rainwater in Columbus has a low PH (my litmus reads PH 5) and is full of oxygen. We'll see if the pollutants are too much for them.
--Steve
(Edited by steveo at 12:53 pm on April 25, 2002)