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Re: N cycling in planted tanks

>From: "Marshall F. Wilkinson" <wilkinso at acs_ucalgary.ca>
>It was mentioned recently that planted tanks do not nitrogen
>cycle. When it comes to microorganisms I would say that the
>former statement would have to be false.

Technically, this would be true.  The period of time that it takes for
nitrogenous bacteria to form an equilibrium in an aquarium where they
quickly convert all available ammonium to nitrate still exists.

However, (as I can see that you know based on your post, but I still want
to point it out for new readers), a heavily planted, lightly stocked tank
does not rely on the nitrogen cycle as it's ammonium/ammonia removal
mechanism.  Nitrifying bacteria still exist, and arguably, probably
establish much faster in a heavily planted tank, but their contribution to
ammonium conversion does not readily compare with the plants' contribution
to ammonium removal by uptake.

Therefore, while it is true that a bacterial nitrogen cycle will occur in a
heavily planted tank, its effects are often unnoticed, and aquarists
starting a heavily planted tank should not expect to see the ammonia and
nitrite spikes and accompanying bacterial bloom (water cloudiness)
associated with beginning the cycle in an unplanted tank.

Plant tanks do go through a cycle, but many of us refer to it as the algae
cycle rather than the nitrogen cycle.  This cycle occurs as the plants
establish control of the nutrients in the water and starve out the algae.
Depending on the care of the tank, this cycle can go in one of many
predictable directions, including:  Red algae -> red algae dieback, plant
explosion -> nutrient deficiency, plant decline -> algae resurgence (red or
cyanobacteria) -> equilibrium.  This is only one example of an algae cycle.
Depending on maintenance, nutrients, and lighting, the algae cycle could be
completely different.

David W. Webb           Texas Instruments
(972) 575-3443 (voice)  http://www.dallas.net/~dwebb
(214) 581-2380 (pager)  2145812380 at alphapage_airtouch.com