What is the limiting factor for Bacteria?

NewObsession

NewObsession

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Bear with me as this may be lengthy but I will try to explain it as best I can.

What is the (or is there) limiting factor when it comes to bacteria growth when cycling a filter other than food source?

What is one wanted to "supercycle" a filter so that it could handle any bio load thrown at it? Obviously the fish in method (other than being frowned upon by many) would have it's limits based on the the size of the tank as you could only add so many fish before space would be an issue even if the filter wasn't.

But in the case of an empty tank ( empty meaning no fish) if you were to do a fishless cycle by addining amonia, what determines just how "cycled" you could get a filter? You can only add so much ammonia (5ppm) so what would max out the size of the bacteria colony? The size of the media? the flow rate of water through the filter? and since you can't pump ammonia above 5ppm what would be stimulus for more bacteria? Or would it simply be a matter of the bigger the colony the faster it would convert the 5ppm?
 
If would be a combination of amount of habitable surfaces and flow. The bacteria needs a place to live so the more surface area you give it the more bacteria could theoretically be present. you also need flow to distribute the food source to every habitable surface. The larger the colony the faster the ammonia would be used up.
 
Bacteria can fairly quickly adapt to the load.(usually within hours)
I'm not sure you would need to have a super colony to adjust.
 
Star_Rider said:
Bacteria can fairly quickly adapt to the load.(usually within hours)
I'm not sure you would need to have a super colony to adjust.
Click to expand...

Maybe Super colony was the wrong term to use. Yes I know they adapt fairly quickly but I was more curious about cycling a filter that could handle any fish load you then wanted to put into the tank, obviously withing reason based on the size of tank and filter
 
I was looking at this in more of a theoretical mindset. ie "How many bacteria could you possibly fit in a tank?" but either way the formula stays the same. more surface area + more food + delivery mechanism (water flow) = more bacteria. any one of the necessary parts could be the limiting factor in a given bacteria colony
 
IME I run spare sponges in my tanks for use as seed filters.. this really all you need.

I have yet to see a seeded filter have any issues when placed in another tank. I've used these to qt a colony of new discus and only had minor spikes that subsided within 24 hrs.

I'm not sure it's necessary to try and pre-overload a filter. My point is that having seeded filter material from an established tank will, usually, quickly adapt to the bio load
 
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While in theory total surface area can limit nitrification in practice oxygen is the limiting factor. Chemically speaking your bacteria are oxidizing ammonia, NH3 into nitrite, NO2 and then nitrate, NO3. Every step of the way requires oxygen. That's why for nitrification nothing beats a biowheel, bioballs, or some other similar media that has a thin film of water trickled across it to provide maximum surface area for gas exchange.
 
I guess what I was getting at was is it possible to cycle a filter so that when added to a tank there was no need to do water changes or wait for the bacteria colony to "adapt". Also whether it made any difference what size tank it was run on. ie if I had a 5 gallon tank, could it be used to cylce filters and the answer appears to be yes. In other words, in a fishless tank, given a regular food source ( ammonia) any filter can be "fully cycled" to accomodate whatever size tank that particular filter is designed for.
 
SubRosa is the closest the 'right' answer. In a finite amount of water the first thing that will limit the nitrifiers is pH. Because each step in the process produces H+ ions, the pH of the water will eventually drop (the more ammonia you add the faster the pH will drop). Once the pH gets below 7 the process slows, below 6 the process stops.

After pH the next limiting factor is usually oxygen. However, the design of the filter makes a big difference. As, again, SubRosa points out, filters like the biowheel and bioballs and other such filters that produce athin biofilm work best but not because the water is thin. It's because the bacterial biofilm is thin. The most effecient filter maintain a thin biofilm so the most cells are get access to the ammonia/nitrite and oxygen. If the biofilm gets too think then the cells are the bottom are deprived of resources and do not perform.

As the data, using microelectrodes, shows the actual zone of nitrification is very thin - just over 100 microns! I turned the figure on its side because I think it is easier to understand that way. The blue layer is the water above the biofilm. The microelectrodes can measure ammonia, nitrite, nitrate and oxygen every 10 microns and show the shaded area is where nitrification occurs.

Nitrifying-Layer_sml.jpg


As the data indicate the real secret to a good biofilter is keeping the biofilm thin.

So once you make sure the pH and oxygen stay high the next limiting factor is getting the biofilm thin. After that surface area becomes important.
 
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