Yeah, there are many many types and sizes of bio-balls and all of them allows very small micron size bubbles to attach for a while, until the bubbles absorb into the water, allowing the balls to float. You can speed up the process of removing these bubbles by severely agitating the bio-balls submerged in water by rubbing them in your hands and you can also soak the bio-balls in an oxidizer solution, such as grocery store hydrogen peroxide, mixed with some water to help absorb these bubbles into the water.
The big bio balls are good for making a protien skimmers
(another explanation of a phoam phraxionator
) or a wet/dry trickle tower (retail version of one, click the middle product image)
or to make a shower tower
(more like a trickle tower since shower towers have a much higher flow, example of a 55gal bucket, filled with big size bio-balls). These can be built in any container or structure as long as the main pieces still function as they are suppose to function.
The all different very small bio-balls are used to create moving bed bio-filters
and here is another one that better shows one in process with video, moving bed in 275gal tote
. These can be built in any container or structure as long as the main pieces still function as they are suppose to function.
Although, the lava rock is heavier, lava rock can make for a nice submerged pre-filter or trickle or shower tower.
So, in choose the type of bio-medium, it all depends on your application, construction, and goals.