I have been doing my homework on bacterial blooms recently, so maybe i can help (not homework literally, i have left school
).
There are 2 types of bacteria at work in our tanks
Autotrophic Bacteria - Bacteria capable of synthesizing its own food from inorganic substances, using light or chemical energy. Our beneficial filter bacteria are autotrophs.
Heterotrophic Bacteria - Bacteria that cannot synthesize its own food and is dependent on complex organic substances for nutrition. The heterotrophs in our aquariums mineralise the organic waste (break down the uneaten food, fish waste, dead plant matter etc into ammonia).
Contrary to popular belief, it is commonly the heterotrophs which are seen in our bacterial blooms, not our trusted autotroph nitrifiers.
It is the heterotrophs which are responsible for creating the "bio-film" (slimy residue found on the tank walls and ornaments)which builds up in our aquariums.
The heterotrophs are generally bigger than the autotrophs and therefore don't attach themselves to surfaces with the same ease. They also reproduce much more quickly. Heterotrophs can reproduce in around 15 - 20 minutes, whereas autotrophs can take up to 24 hours to reproduce.
In a newly set-up aquarium, the heterotrophs get to work quicker than the autotrophs, causing the 'cycling bloom' we so often see. Poconoboss, i would place money on it that your bloom was heterotrophic as it seemed to be caused by the build up of organic waste in the substrate.
Our autotroph nitrifiers are strictly aerobic (require oxygen), but the heterotrophs can be facultative anaerobic (they can switch between aerobic and anaerobic function depending on their environment). Therefore the heterotrophs in the substrate will be in their anaerobic state and breaking down the organic waste into ammonia, but if they bloom up into the water column, they will switch to their aerobic form and will start to convert the ammonia back to nitrite, although very inefficiently. The heterotrophs are around 1,000,000 times less efficient at ammonia oxidisation than our beneficial autotrophs as the heterotrophs are not true nitrifiers.
Most of the bacteria in the aquarium are aerobic as it is a oxygen dominated environment, and these bacteria require lots of oxygen. When the heterotrophic bacteria bloom into the water column and switch to their aerobic state, this is a big drain on the oxygen content of the water. Oxygen depravation is the only risk to the fish which i am aware of during a bacterial bloom, as the heterotrophs themselves are harmless to fish. Tokis, good advice to increase aeration!
Shortymet, i hope i have helped you to understand why your bacterial bloom occurred. Your apparent overfeeding caused a sharp rise in the reproduction of the heterotrophs in order to start breaking down the uneaten food, and this caused your bacterial bloom. As the ammonia production increases due to the increased mineralisation, the nitrifiers are slow to catch up (as i said above) and so you see an ammonia spike until the autotrophs reproduce enough to take care of it. Contrary to popular belief, your bacterial bloom caused your ammonia spike, not the other way around.
I would suggest that a thorough gravel vac will certainly help the situation, as will adding live plants. Also, try not to overfeed. Water changes will probably not clear the cloudiness as when you remove the free-floating bacteria, the others reproduce more to compensate. Reducing the amount of organic waste in your tank is the ultimate solution to ridding your tank of its cloudiness.
I am uncertain whether the nitrifiers ever bloom into the water column or if they simply multiply too slowly to cause this effect.
With regard to the water changes, i agree with Andywg. To say that 10% weekly is the maximum water change recommended is no more than a fishkeeping myth. So long as the replacement water is of a similar composition to the water removed, the bacteria will take water changes in their stride, even at 100%.
Also, other than in the situation of a bacterial bloom, a water change will remove virtually no bacteria from the tank at all as 99% of the nitrifiers are housed in the filter, not in the water column. Even during a bacterial bloom, it will be heterotrophs which are removed via water change, which will have no effect on the cycle.
Hope this helps.
Cheers
BTT
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