My homemade K1 moving bed filter sits inside a homemade sump; it took a number of experiments to get the shape of the K1 compartment just right for the K1 media to start circulating properly, and it took several days of running it in its final configuration before the K1 itself seemed to achieve some mystical "neutral buoyancy" state that allowed it to tumble as desired. It also uses probably as much air as all my tanks combined!
I think it's largely a waste of time. Sure, the K1 has a lot of surface area...but the tank is only going to support as many bacteria as the bioload allows; it was perfectly cycled before, so adding this thing did nothing functional for me. Yes, of course the K1 fanboys will trumpet how the tumbling action allows the media to "self-clean", sloughing off the older, weaker past-their-prime bacteria if favour of their younger, fighting-trim brethren...but, again, so what? A filter that works...i.e. maintains a sufficient bacterial population...is not going to work "better" by adding K1. The total bacterial population of the tank won't change, unless the bioload changes either through fish growth or the addition of more fish...and in those cases, the bacteria would have grown just fine on the old media. Proper mechanical pre-filtration will minimize the rate at which static biomedia clogs up...and most filters allow pretty easy access to the biomedia for the very occasional rinse required to negate the clogging.
If you intend to use only K1 it might make a bit more sense...but it looks like you already have some other biomedia in there. Are you planning on replacing that with K1?
I put this stuff in there for two reasons: because I got a bunch of it thrown in on a trade I was making, and because my young granddaughters loved watching it tumble as much as they enjoyed watching the fish. They've sort of outgrown that fascination...and the tank stand is now enclosed, so the K1 isn't really visible anymore (and it sounds like yours won't be either), so the only reason I still use it is because it's easier to leave it in than to remove it.
