I got two grobos now and the brand new one seems to produce less but bigger bubbles. Is there a risk here?
(Maybe there is a difference):
Interesting. Did you check to see if the air pump a different model from your 1st one?
The air bubbler seems to be one of the most troublesome parts of the Grobo.
I actually swapped the pump in both grobos with a USB powered one that is way quieter. I pulled the air stone in the one and found that it had a small chunk missing from it. I replaced it with a round stone that came with my pump… looks much better