Ratio of bio-media to gallons of water

[Naos1984]

I know this may be a silly question, but do we have something like this? Or is this entirely dependent on bio-load? I'm referring to how many kg of bio-media is needed per gallon of water. There are far too many variables like type of media and surface area of each type but do we even have a rough estimate?

 

[Tahn]

Many bio-media per a lot of water.

 

[Drstrangelove]

This is actually a very complicated calculation that requires information that people ordinarily don't have and that changes over time. (I tried to do this once and it was terribly frustrating when I was done and realized it had no practical benefit.)

There's no reason to know it since a) lots of people can give you their own experience and b) the cost of having too much is much smaller than the cost of having too little.

It's like asking exactly how much money a person will need when they go to the store for groceries.(Assume no debit or credit card!) The exact number will require all sorts of assumptions, any one of which is wrong, and many which are simply unknown until you get to the store. And if you miscalculate too little, even by a dollar, you'll have to leave something at the store. The rational choice is to always take too much, and given the cost of going home, probably a whopping 30-40% too much.

 

[skjl47]

Hello; The way I look at it is the actual working population of beneficial bacteria (bb) is dependent on the bio-load and not the amount of water at all. The OP indicated a grasp of this in the initial thread. A fish in a 20 gallon tank will support a particular bb population. That same fish in a 200 gallon tank will support that same bb population.

That said there can be an advantage in having the much larger tank. More volume to dilute any toxins that build up, more stable temperatures, less stress on the fish with fewer stress hormones in the water and so on. In general the bigger tank nearly always being the better choice.

I come from a time when the only filtration systems available were the UGF and very low flow air powered mechanical filters. Yet the tanks were cycled without the modern power filters having the large bio-media chambers. I guess the gravel was part of the bio media and the UGF made sluggish but sufficient flow. I also think the bb populations formed on many surfaces.

Maybe the single biggest thing with regard to the amount of bio-media needed is the stocking density of a tank. With very light stocking densities the amount of surface area needed for the bb to form a bio-film is likely not an issue. However with high stocking densities that are so common in the hobby there are much larger amounts of ammonia and such constantly produced by the fish and the decay of excess food bits. As Drstrangelove stated it is better to have too much than too little.

One other point that is not often discussed is keeping the bio-media clean. Folks want stuff with lots of surface area in a small volume. Fairly early on I found it important to have some sort of good and replaceable mechanical filtration ahead of the bio-media. The more of the physical detritus trapped, then to me the less the bio-media gets clogged up with the stuff. I am also a big fan of replacing that replaceable media on a regular basis.

One last question. I have been puzzling over the popularity of bio-media materials such as ceramics and other material with very fine pores. The bb form a bio-film on surfaces is my understanding. I have also noted that over many months or years of running a power filter that a fairly thick film forms on the inside of the filter parts.
Now I get that the tiny pores in a bio-media are like huge caverns to the bacteria and do get that having a multitude of these pores inside such media gives more surface area for the bb to colonize. My question is what prevents these pores from being clogged up over time??

 

[J. H.]

I know this may be a silly question, but do we have something like this? Or is this entirely dependent on bio-load? I'm referring to how many kg of bio-media is needed per gallon of water. There are far too many variables like type of media and surface area of each type but do we even have a rough estimate?

It has to do with bioload and oxygenation, if you look at any good auquaponic website, they have good rules of thumb. It has to with surface area, so a cubic foot of playsand with water running through properly is worth probably ten cubic feet of bioballs,even if it is harder to care for.

My question is what prevents these pores from being clogged up over time??

this is exactly why I don't use it. My understanding is that people who do take out about a fifth of their media every now and then and powerwash it, losing their bb in the process.

 

[duanes]

If biomedia is not regularly cleaned of detritus, the gunk can restrict oxygen from getting to the beneficial, aerobic bacteria (biofilm).
And I agree about stocking being the main concern.
If you have overstocked the tank, I believe you should overload with media.
If you have a pair of fish in a large tank, you can be assured your media, and everything else in the tank will probably be sufficient.
But lots of fish, in a too small tank, with the basic standard aquarium lore filtration, maybe not.