What is the limiting factor for Bacteria?
- Thread starter NewObsession
- Start date
So this means that Wet/drys are probably the best biofilters out there, a lot of trickling water provides a thin biofilm and a lot of oxygen? Does this also mean that porous media is somewhat inefficient at producing aerobic biofiltration because the bacteria that are closer to the center are rid of oxygen, and why most biomedias have a "hole" in the middle of them? A lot of great information here, Thanks DocTim.
The hole simply allows for greater surface area by utilizing the inside of the media. Your hard surfaces is the collection point for most of your bio-film (i.e. gravel, glass, etc.), they are not the only place. Anything that can offer a hard surface (non-liquid), is utilized. The filter itself is not a great collection point when compared to the tank itself.
Ammonia is the catalyst that starts the "cycle". So you need ammonia for the cycle chain to be complete. Your ammonia is generally too low to measure as is your nitrite, however they support the nitrate that continues to convert what otherwise would be a toxic condition.
Introduction of more fish simply increases the amount of ammonia which needs to convert to nitrate to be safe. The amount in your water column is one of the main ingredients in controlling a bio-load. Too little water cannot off-gas or dilute the unwanted characteristics.
A filter is the source for keeping suspended waste out of the water column. That which the filter cannot uptake simply lands in the bottom creating your mulm where is becomes a part of the decay process.
I personally have found a heavily planted tank to be ideal as method to control high ammonia, nitrite, nitrate. I had a severely planted tank that was able to control a heavily overstocked bio-load. Because of the plants uptake, I did water changes only once every 6 weeks.
Ammonia is the catalyst that starts the "cycle". So you need ammonia for the cycle chain to be complete. Your ammonia is generally too low to measure as is your nitrite, however they support the nitrate that continues to convert what otherwise would be a toxic condition.
Introduction of more fish simply increases the amount of ammonia which needs to convert to nitrate to be safe. The amount in your water column is one of the main ingredients in controlling a bio-load. Too little water cannot off-gas or dilute the unwanted characteristics.
A filter is the source for keeping suspended waste out of the water column. That which the filter cannot uptake simply lands in the bottom creating your mulm where is becomes a part of the decay process.
I personally have found a heavily planted tank to be ideal as method to control high ammonia, nitrite, nitrate. I had a severely planted tank that was able to control a heavily overstocked bio-load. Because of the plants uptake, I did water changes only once every 6 weeks.
A properly run wet/dry will oxidize more ammonia in a given period of time than any other filtration system. And as far as adapting to a sudden large increase in ammonia addition even a heavily planted tank will be at a sort of equilibrium with the normal rate of ammonia production and will require a period of time to be able to handle a large increase in production. And in this period of time it is most likely the bacteria that will pick up the slack. This is of course excepting a situation where nitrogen is the overall limiter on plant growth which is possible but not likely in a tank heavily stocked with fish. Bacteria are able to increase their #s and adapt much more quickly than plants.
GoldLenny
Senior Member? Do I get a 5% disc.?
I kind of remember reading in some of Dr. Tim's early published papers, when he was still the chief science officer with Marineland, that a normally stocked tank to slightly overstocked tank will create around 3ppm to 5ppm of ammonia each day and that is why we target that level when fishless cycling a tank using plain ammonia. I also remember that nitrifying bacteria can double their colony size in 24 hours if there is sufficient food and O2. As others have stated, if you have tons of ammonia and not enough O2, then you will likely have elevated ammonia problems.
Also, if your KH level gets too low, you will likely have problems... as all life forms need carbon. I know that for some folks, when fishless cycling, if their KH level got down to 1-2 dH, their fishless cycle would often stall and then doing a PWC kicked it right back into high gear again.
Also, if your KH level gets too low, you will likely have problems... as all life forms need carbon. I know that for some folks, when fishless cycling, if their KH level got down to 1-2 dH, their fishless cycle would often stall and then doing a PWC kicked it right back into high gear again.
Interesting graphic Dr Tim. So how do we keep our biofilms thin? It does seem like all the "micro-pores" of ceramics would fill up, bio-wheels form a thick slime...are you saying I need to clean my back glass?!?! Rinse our media more often to prevent build up?
GoldLenny
Senior Member? Do I get a 5% disc.?
As far as rinsing our filter media more often, I like the analogy used by Bill, a Koi ponder who also owns a large pond supply distributorship in GA. I have this analogy on my blog's post about filter maintenance which is also an article on AC.
FILTRATION:
HAVING TO CLEAN A FILTER CAN BE GOOD.
First of all, if a filter does not collect junk and clog, it isn't doing its job and working to get the junk out of the water.
Since IT'S ALL ABOUT WATER QUALITY, the filter is supposed to take organics out of the water to IMPROVE water quality. (Inorganics = rocks = really aren't a problem.)
If a filter catches organics and the filter is not clogged (yet) but also not cleaned - then the organics can dissolve and go back into the water in solution = LOWERING THE WATER QUALITY.
SO, the object of a good pond keeper is to IMPROVE water quality = clean the organics from ANY filter BEFORE they dissolve = every other day, every third day.......
Sorry for bringing reality into your lives....
I know everyone wants a filter that doesn't EVER need to be cleaned.
Imagine that the filter catches poop. So it is the fishes' toilet.
How often do you clean (flush) your toilet? Why? Why not the fishes' also.
Bill
----------------
(END SNIP)
FILTRATION:
HAVING TO CLEAN A FILTER CAN BE GOOD.
First of all, if a filter does not collect junk and clog, it isn't doing its job and working to get the junk out of the water.
Since IT'S ALL ABOUT WATER QUALITY, the filter is supposed to take organics out of the water to IMPROVE water quality. (Inorganics = rocks = really aren't a problem.)
If a filter catches organics and the filter is not clogged (yet) but also not cleaned - then the organics can dissolve and go back into the water in solution = LOWERING THE WATER QUALITY.
SO, the object of a good pond keeper is to IMPROVE water quality = clean the organics from ANY filter BEFORE they dissolve = every other day, every third day.......
Sorry for bringing reality into your lives....
I know everyone wants a filter that doesn't EVER need to be cleaned.
Imagine that the filter catches poop. So it is the fishes' toilet.
How often do you clean (flush) your toilet? Why? Why not the fishes' also.
Bill
----------------
(END SNIP)
The key to the biowheel* and other types of rotating biological contactors (RBCs) is that the rotating action keeps the biofilm thin. Since the wheel is always rotating when the biofilm starts to get too thick the movement of the wheel causes a portion of biofilm to slough off. The same kind of thing happens in fluidized bed filter except here the action of the fluidized media rubbing against each other causes an abrasion action that keeps the biofilm thin.
Trickle filters do not have a 'natural' action that keeps the biofilm on them thin and because is can be so hard to keep all the media wet they can build-up a biofilm and also have dead spots.
In general, the most efficient biofilter is the RBC - all the media is wet but also exposed to air and the biofilm is kept thin.
Next is the fluidized bed or versions of it but the problems here are the media is always underwater so oxygen transfer is limited and as the media grows the biofilm it gets heavy and sinks and the media also tends to stick together.
Trickle filters are third - they need good water flow over all the media and a way to remove the organics that build up. One version has the biomedia in a cylinder that turns as the water flows over it and this work well.
Undergravel filters are usually last because they clog - any biofilter that also acts as a mechanical filter usually does not perform well compared to the others listed above. They can and do work but you must keep them clean so water can flow over the gravel particles. A good siphon cleaning - say 1/2 the bed one week and the other half 2 weeks later usually is sufficient and you get the water change done in the process.
I would not worry about the back wall - that area probably has a lot of algae and bacteria predators so there aren't a lot of nitrifiers which don't like light so they tend not to grow on the aquarium walls much.
The take home message - what ever biofilter you have keep it clean so it has a thin biofilm and don't let it clog with organic debris.
* full disclosure - I was part of the research and engineering team at Marineland that developed the biowheel but I am no longer associated with marineland and have no financial interest associated with any of those companies
Trickle filters do not have a 'natural' action that keeps the biofilm on them thin and because is can be so hard to keep all the media wet they can build-up a biofilm and also have dead spots.
In general, the most efficient biofilter is the RBC - all the media is wet but also exposed to air and the biofilm is kept thin.
Next is the fluidized bed or versions of it but the problems here are the media is always underwater so oxygen transfer is limited and as the media grows the biofilm it gets heavy and sinks and the media also tends to stick together.
Trickle filters are third - they need good water flow over all the media and a way to remove the organics that build up. One version has the biomedia in a cylinder that turns as the water flows over it and this work well.
Undergravel filters are usually last because they clog - any biofilter that also acts as a mechanical filter usually does not perform well compared to the others listed above. They can and do work but you must keep them clean so water can flow over the gravel particles. A good siphon cleaning - say 1/2 the bed one week and the other half 2 weeks later usually is sufficient and you get the water change done in the process.
I would not worry about the back wall - that area probably has a lot of algae and bacteria predators so there aren't a lot of nitrifiers which don't like light so they tend not to grow on the aquarium walls much.
The take home message - what ever biofilter you have keep it clean so it has a thin biofilm and don't let it clog with organic debris.
* full disclosure - I was part of the research and engineering team at Marineland that developed the biowheel but I am no longer associated with marineland and have no financial interest associated with any of those companies
Ah I knew that 
:
But seriously folks - regarding the micropores and clogging - this does happen and some think that this can be good because it will promote an anaerobic environment where denitrification can take place. But the problem is that you still have to get the water to flow through the pores which can be difficult because water takes the path of least resistance (generally onto your floor).
There have been a lot of different media all talking about micro-pores and surface area but they generally do not work very well due to clogging.
:But seriously folks - regarding the micropores and clogging - this does happen and some think that this can be good because it will promote an anaerobic environment where denitrification can take place. But the problem is that you still have to get the water to flow through the pores which can be difficult because water takes the path of least resistance (generally onto your floor).
There have been a lot of different media all talking about micro-pores and surface area but they generally do not work very well due to clogging.
