Bacteria build up on my media observation.

[JohnHuff]

This is actually to do with media in my indoor tank but I suppose it would apply to a pond as well.

I have a home built moving bed filter with K1 media. It's a flat box with K1 inside and air flowing up from the bottom. The air flows through and around the K1 in the box and exits the top. The K1 is supposed to form a brown film over it and that brown film is the bacteria.

Recently part of the top of the box came loose and a bunch of K1 media came out. The K1 floats and got mixed in with a bunch of floating broadleaf watersprite. Because of the holidays I left the K1 floating there.

Imagine to my surprise when over the last 2 days I found the K1 covered in a nice very brown film of bacteria whereas the K1 in the filter is still relatively white after a couple of months. How could this be? I thought the bacteria loved oxygen and did best with copious oxygen flowing around it.

Has anyone else had an experience like that, and/or we all doing this wrong and should we not be running air over our media?

Hmm, I'm not sure if this should be in the Water chemistry forum. Please move if it is so, TIA.

 

[Mucky_Waters]

How about some pictures of this set up John.
Are you sure the brown film is bacteria and not algae? Is the K1 media exposed to more light in the aquarium than it is in the moving bed filter box?

 

[JohnHuff]

Sorry, don't have any pics at the moment. Its just a box with K1 inside and an air diffuser underneath.

Yes, I'm pretty sure it's not algae. It's just a brown film. The K1 is more exposed to light when it's floating, but I don't think it makes a difference because I also see this brown film elsewhere, like on the nylon screws that's holding the box together. The nylon screws are not in the air column. It seems that the bacteria is avoiding the air, which is contra to what it is supposed t do.

 

[Mucky_Waters]

Perhaps the brown is actually dead or dying bacteria, and the live bacteria is invisible???
I think it was in another thread somewhere you mentioned that you could feel a sliminess on some media and assumed that was a sign of the bacteria coating. I commented that I also thought I could smell the bacteria, and that I thought it had a fishy smell. My evidence for that comes from a number of sources, including aquariums where I have done fish-less tank cycling. On occasions where I had done fish-less cycling the aquarium tank the filter media would take on a light fishy smell with no fish at all in the tank. I've always assumed that smell was the bacteria colony establishing itself. The exact same smell can be found in many natural water sources, pick up a rock in any fresh running stream, it has the same smell.
Anyway, I've seen that light brown color on bio-media before, and on the aquarium glass itself (it also has that fishy smell), but I've also felt that sliminess, and smelled that fishy smell on bio-media before that didn't have the brown color yet. The brown color seems to be a something that develops later, perhaps it is a sign that the bacteria is so well established that some of it has started to die (turning brown)???

As for the fishy smell, if it isn't coming from the bacteria, then someone needs to explain to me where it's coming from. If it comes from a pond or aquarium or natural body of water with fish it's easy to assume it coming from the fish, but when it develops in tanks or ponds with no fish, then you can no longer make that assumption.

edit. please rub and smell your bio-media, tell me what it smells like to you?

 

[JohnHuff]

You're right about that. I had forgotten about the slimy feeling. This whole brown thing is from these youtube vids such as:

and
http://www.youtube.com/watch?NR=1&v=9YNwrTeHNHs&feature=endscreen

One of them says that the media matures and turns brown and that's the bacteria. The top one also says it matures in 3 months which seems a long time as I thought fishless recycling only takes 4 weeks. The whole tank actually has a fishy smell too!

If it takes 3 months for the bacteria to mature then I wonder if we really need artificial filtration where i live in Seattle as the temperature is only feasible 4 months for the bacteria to live. Both the beginning and the ends of the ponding season are too cold and you've really only got 3 months in the middle of hot weather.

 

[Waterbug]

I think the issue is there is a lot, virtually all, of info on the net about ponds, bacteria and algae is what people think is true. It's their opinions, passed round and round so may times and for so long that it may appear to have some basis in reality.

Most bacteria in ponds is not nitrifying bacteria. Tests I've read on bio filter media something like 90% (I don't remember exactly, but a lot) of the bacteria were other species. Seeing or feeling a bio film doesn't mean just nitrifying bacteria, lots of bacteria secrete a bio film.

The studies I've read, for the couple of species studies, the bio film was more pinkish than brown. That's in a lab. In a pond or tank I assume dirt, other animals and plants live on the bio film too. Plus the bio film from other species could be other colors, but I don't know that.

Nitrifying bacteria will grow where they grow. In full sun, low O2, where ever. The ones that happen to land in the filter can over time reproduce faster than those is crappy conditions. So over time, and we're talking months because these bacteria reproduce slowly for a bacteria, before a bio filter would contain a disproportionate amount of nitrifying bacteria. And more than likely I would assume the highest concentrations (per sq in) would still be found out side the filter, in pump pipes for example. And there would still be a lot throughout the pond.

I don't know where the idea of being able to smell nitrifying bacteria comes from. First I've heard of that one. Since 99.9% of the organic stuff in a pond or tank is not nitrifying bacteria and much of that is being decomposed by other species of bacteria which do give off odors we associate with ponds, lakes, rivers and even streams, I'd assume that would be the source of the smell. I don't know of any chemicals that nitrifying bacteria produce have an odor, but I'm not sure. Given the small percentage of nitrifying bacteria to other bacteria I think it would be impossible for a human to be able to detect odors from the nitrifying bacteria.

My assumption would be any slime film of any color would be a bacteria bio film. But which species of bacteria? I don't see how that could be determined by the naked eye, smell, licking, etc. For sure I'd be betting money that most of the bacteria found in bio film in any location (outside of a lab) would be mostly not nitrifying bacteria. For sure people do seem to see, smell or taste what it is they "want" to and stories are created to support their belief. Doesn't mean it has any basis however.

Nitrifying bacteria can of course be detected by measuring ammonia and nitrites by the levels of each changing. And by the rates of the level changes a good estimate of animal population can be computed. But none of that tells a person where exactly the animals are living in the pond. When a pond does have high ammonia levels that stay up due to fish load and a bio filter is added and levels decrease it's a pretty safe assumption there is nitrifying bacteria in the bio filter if everything else stayed the same. But most of the nitrifying bacteria would still probably be located outside of the bio filter at least for the first several months.

 

[Mucky_Waters]

Although it's true that we have no way of knowing for sure that it is specifically, or exclusively, nitrifying bacteria that are responsible for the fishy smell on healthy bio-media, the fishy smell does seem to be a pretty good indicator that at least the proper type of bacteria colony is being established, even if the true nitrifying bacteria only make up 1% of the colony. As I mentioned in the previous thread, where we touched on this subject, we know that nitrifying bacteria need oxygen, and it doesn't take long for them to die if they are deprived of it. A little test you could do, and, perhaps like me you have done this completely by accident before, is cut off the oxygen source to some established bio-media and you will notice that fishy smell soon disappears, and if you seal it up tight enough so it has almost no free oxygen getting to it at all, that fishy smell will be replaced with a putrid rotting smell when sulfide producing bacteria start eating the bacteria that died on the bio-media, you can smell them too, or at least you can smell the sulfides they produce.

Perhaps John would be willing to sacrifice his little K1 bio box, for this little test. If you are crazy enough to try it John, be sure to also observe any color change that occurs with the K1 before and after the test.
Of course to do the test properly you should have observed any color, feel or smell before starting the test, but I think we could safely say the K1 was white, and had no smell and had no slimy feel.
Now that it has established bio film I'm guessing it likely has a slimy feel, a light brown coat, and a slight fresh fishy smell.
Now remove it from the water flow, turn off the oxygen and seal it up, give it a day and report back to us what you observe.

 

[minnowman]

The abrasion of the media hitting each other in a moving bed biofilter reduces the bacterial film on the outside surfaces of the media without reducing the ammonia conversion rate because the thicker film on the non-moving media does not allow water flow to the bacterial cells deep inside the film. Nitrifying bacteria can live in total darkness as well as in lighted areas, but many other types of bacteria can out-compete them in the light.