Filter capacity/speed and its effects on cycling

[93MSB]

I had couple questions about filters and what the best conditions are to grow bb in them

my first question is about filter capacity (i.e. running 2 40-60 HOB's on one 30gal tank)

im assuming since both filters see the same amount of ammo and nitrite the amount of filter capacity doesnt effect the quantity or speed of the BB growth rate.

my second question is about the speed at which the water flows through the filter.

would a hob filter grow bb faster if the flow was set low where there was less disturbance? or would it grow faster with a higher flow and more aeration?

 

[Cichlid Kid]

BB is aerobic bacteria and as such thrives in a well oxygenated condition. Imo the best filters to offer a density of bb per sq. in. better than any other would be a wet-dry trickle filter.
I know that doesn't answer your question but as for HOB's, I would say one that offers complete pass thru "cycling" of water at a rate of at least 3× your tank volume an hour would be a good place to start.

 

[CrashCourse]

I'm looking at a similar thing right now, and I think the speed and bb are two different functions.
I have both the biowheel style with cartridges and the sponge/biomedia style in different tanks.
My thought is that the more surfaces for bb to grow, the better, and you don't lose so much when you change a cartridge. The speed helps to filter out more impurities faster, so the water is clearer.
I'm kinda leaning more toward the sponge/biomedia side, and started adding in extra biomedia between my cartridges for extra bb growth. Having gone through mini cycles after changing filter pads, it seems like a little back-up system. I don't know how/whether the filter speed has any affect on the growth itself. That's a good question.