Wy Renegade
Aquarium Advice Addict
Two points here that I want to weigh in on briefly. I'll come back and hit more points when I get home from work.
I disagree with this. You're thinking to much about volume and not enough abut surface area. I looked up the surface area of the ceramic "Ehfisubstrat" that came with my canister filter, and it is marketed at about 20,000 square feet per gallon. I have about 3L in my filter (more than the 2L that it comes with). So, after some quick math, my little 2217 has just under half an acre of surface area. All/most of that surface area is readily supplied with nutrients and oxygen by the flow of the filter, meaning that the bacteria colonies can be larger and more robust. Compare that to the substrate where only the top inch or so is really supplied with nutrients. Low layers would still have aerobic bacteria, but they won't be thriving like the upper ones would be, and even those bugs envy the life of filter-bacteria.
Ah, welcome my friend, I was hoping that you might join the discussion. Like yourself, my participation will have to end soon, but I will be checking back in later to continue the discussion.
So to your point, let me simply ask this, what is the total surface area that exists within the top inch of say your aquarium given your substrate. No idea if your tank contains either sand or gravel, yet given the larger volume of gravel or sand within that area, if you calculate the actual surface area (which in an adequately filtered aquarium should have the same flow/oxygen levels/etc), I have a hard time believe that the actual surface area will not be signicantly higher. We cannot factor in the porousity of the ceramic media while excluding the either the porousity of the sand or rock, nor the grain size which creates more surface area within that volume, can we?
I really don't think that the water in filters is especially oxygenated. Maybe some filters (biowheels), but it seems like most of mine only have water/air contact right before the water leaves the filter. My AC is certainly this way.
Agreed, indeed the flow generated by the filter itself should adequately distribute said oxygen evenly without and in little to air contact is made within the filter itself.
The second thing is something that has intrigued me for a long time, and that is the role of phytoplankton in our ecosystems. They are present in both salt and freshwater, and they have to be getting their nitrogen from somewhere. So while I due doubt that bacteria has a major presence in the water, I would imagine that there could be a whole host of other organism, autotrophic or otherwise, floating around that could also make use of nitrogenous byproducts. I find it hard to believe that there is only one organism that can make use of a single, readily available resource like reduced nitrogen. We see this in plants as well.
Indeed this is true, however keep in mind that the term phytoplankton is in and of itself some ambigous; phytoplankton includes not only protists, but bacteria and algae spores as well as full blown microscopic algae, all of which are involved in the uptake of nitrogen at all times. Green water anyone? Dioflagellate bloom perhaps?
For anyone that is interested, the cloudy water we see is from (if I recall correctly) heterotrophic bactceria. Our nitrifying bacteria are chemotrophs.
No, no I don't think so. Our nitrifying bacteria are autotrophs, but they are definitely not chemotrophes (if they were we would have to have many chemical reactions occurring and chemical gases being released within the aquarium that we have absolutely no interest in). Perhaps you confused your terms?
I don't think anyone is arguing that there is no bacteria in the water column. It's just that there is a ton more attached to surfaces. Think about your garbage can. You can sanitize a trash can and put sanitized food in it, and if left unsealed out in the open, it will begin to mold, rot, and whatnot. Thats because all of those fungi and bacteria and god only knows what else are everywhere. They're even in the air you breath. In fact, I bet you just sucked some in just now! But compared to on the surface of about anything, there's a trifling amount. But you certainly wouldn't eat a decomposing sandwich.
Oh good, then perhaps we can lay the old wives tale that nitrifying bacteria does not exist within the water column to rest? I certainly agree that there is substantually more to be found on surface areas than in the water or in the air, but they do also exist within both places (or at the very least their endospores do)
An additional concern: It is entirely possible that bacteria will not multiply properly (or quickly) without an attached surface. Much of the bacteria in water will come from established colonies on a surface somewhere. The bacteria breaks off and floats along until it finds another surface. Many bacteria (not sure about out nitrifying bacteria) have life cycles like this.
Indeed I can agree with this very readily, I would add only the likelyhood that endospores from existing bacteria colonies are also most likely released into the inhospitable environment of the water column. Upon being provided with a suitable surface such bacteria are sure to begin growing and colonizing all available surface areas with viable conditions.