There good if you don't want a lot of current, or want to direct the current in a certain direction. I inject pressurized CO2
and the airstone makes too much current, which can send a lot of the CO2
into the air rather than keeping it into the water column.
I have an aquaclear 70 on my 29 gallon and I love it but it doesn't move the water around much at all and I love that about it, but stagnate water has caused some problems in my tank and I could really use a powerhead for the other side of my tank.
I like my AC HOB
so I'll most likely go with an AC
Thanks for all your responses.