How much bio media?

[bossanova]

Maybe one of the experts here knows this. Is there any way to estimate how much bio media one needs per adult discus?

I’ve always vastly overfilled my filters/sumps with bio. I figured without much surface area due to little/no substrate it couldn’t hurt to have more in the filter. But still, I’ve got 6lbs of ceramic rings, another lb or so of misc. bio accrued over the years, and a bio brick for good measure (11 sun-adults that im feeding heavily). I can’t imagine there’s enough ammonia being created in this tank to warrant this much media. On the other hand, this tank is solid and I’ve never had any issues with ammonia spikes, mini cycles, etc.

[Hicgup]

There is a way to calculate, not just estimate how much filter material you need. You do need to “know” a few things for a true calculation: biofilm carrying capacity of your media, amount of media (in proper condition in your filter-meaning proper age Kaldnes can take up to a year to mature and needs to be constantly moving—most filter media just needs good even water flow- no channels or dead zones) & percentage of protein in your feed.
As an example Kaldnes K1, 3 cu. ft. Can convert TAN from 512 pounds of fish fed 42 % protein feed fed at 3% body weight per day.
I like to have more filtration capacity than not enough, but in the case of Kaldnes it has to be constantly moving so a fill rate of 25 to 30% is typical with 35% being about ideal. 40% is usually the maximum as a greater fill rate usually results in non moving areas of media which GREATLY reduces nitrification.
For you as long as you have good water flow, no channeling, dead zones, or buildup or organics you should be golden.
Proof is in your water quality testing results, as long as your Ammonia and Nitrite readings are always good, you should have enough filter media for your fish load and feeding regimen.

[Iminit]

More can’t hurt. Thing is your bacteria will grow as the fish get bigger. Bacteria only grows to what it can eat. Lol 6lbs is a lot but I’m using bailing type of media which has a huge surface area. Can’t imagine I’m using more than 50% lol. Yes many of us do have way to much media :).