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Re: Aquatic Plants Digest V4 #222
In a message dated 4/16/00 4:06:49 AM Eastern Daylight Time,
Aquatic-Plants-Owner at actwin_com writes:
<< So this idea of Reverse Photoperiod cycling shouldn't work really, correct?
> Perhaps some as the plants get towards the end of the dark period? But the
> bacteria will work all the time.
> Do algae use N at night also like the bacteria and plants? To what extent?
> If they do, what the heck is this notion of Reverse Photo period for
> filtration? If the nitrogen is being used up by both the plants and the
> bacteria and maybe algae then why do these companies promote the Reverse
> photo period idea as being an some sort of advantage when using
> scrubbers/filters for N removal?
> Tom Barr
Being deeply into the marine reef aquarium hobby I know for a fact that the
reverse photosynthesis type of biological filtration does work. When done
correctly it works extremely well as a matter of fact. A significant amount
of nitrogen and phosphorus is removed due to the extremely favorable
conditions for photosynthesis that is maintained in the reverse day light
chamber. This also results in a more stable pH and alkalinity. I have seen no
evidence that photosynthetic plants, algae, or bacteria consume nitrogen to
any significant degree in the absence of light. Some bacteria and algae can,
when deprived of light, switch to chemosynthesis but this is not nearly as
efficient in consuming nitrogen as photosynthesis. Also in the marine tank
reverse photosynthesis biological filtration can be combined with a refugium
to supply the main tank with small amounts of plankton to feed invertebrates
that are normally difficult to feed. If reverse photosynthesis coupled with a
refugium would have this effect in a freshwater tank I really cannot say. A
marine aquarium operates best when the water contains much less nutrients
than the normal freshwater plant tank. In the wild freshwater will almost
always contain far more nutrients than marine water, There are of course
exceptions to this but I am mainly comparing the water on the reef to water
in a stream or pond with a significant growth of plants.