faulty airstones??

[fishycanuck]

What the heck?
I have been through three airstones this year.
The first one, a blue triangle one about 25 cm long, never really produced bubbles past the first cm. I replaced it figuring it was a dud with a similar one. It, too, only produced bubbles in one small place.
last week, it stopped producing bubbles at all, which I believe led to the death of one of my discus.
I replaced it with a different kind, again about 25cm long but flat. Initially this one produced bubbles in the first two cm but they were very vigorous. After about a week, there is only one "line" of bubbles coming off this thing.
Do I need a stronger air pump? A different stone?
Help!
(apologies for the cross posting - I wasn't sure if this post belonged here or in equipment)

[Aquaticfinatic]

I'd say stronger pump but I'm not a fan of air stones. Try the wooden ones if you can find then. Finer bubbles too.

[bergenm]

I would hazard a guess you need a new diaphragm for your pump.

[lucius]

Don't forget to place a check valve in between the airstone and pump.