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Daphnia vs. air diffusers: a myth?
I've been playing with daphnia cultures for about a month now.
I am using the "green water" feeding method, but instead of raising
the daphnia in the green water, I keep the daphnia and the food
source separate. This provides me with much better population control
which theoretically should prevent "cycling."
My green water tank is a ten gallon with 24hour lighting. A large
bubble wand keeps the water vigorously turning over, and I "feed"
it with a couple alfafa pellets once a week (an experiement, not
yet a "tried and true" technique). Anyways, I recently noticed that
the green water was beginning to clear up. I initially thought that
the alfafa was not providing enough nutrients. However, on closer
inspection, I found that my green water tank was infested with
daphnia! They appear to be doing quite well.
This prompts the following question. Prior to obtaining a daphnia
culture, I did lots of reading about them. Almost every source
stated that using a bubble diffuser will kill them because air gets
caught under their shell. Their is no question that the air gets
trapped. (I did a quick harvest and tossed them in with my discus...
most of them buzzed around the top of the water and had trouble getting
down.) What I'm wondering is if the statement "supplemental air in
a daphnia culture will kill the daphnia" is a myth?
Perhaps this is true in an environment where food is sparse? In this
circumstance, the algae was so thick that visibility was about one
inch and the water is practically in a rolling boil due to the bubble
bar. So... the food source would be constantly available even if the
daphnia had trouble swimming.
Has any one else had a similar experience that seemed to debunk the
age old "don't use air" advice?
(P.S. In my "normal" daphnia culture, I do use a small amount of air...
no diffuser, and about one bubble per second. I figured that these bubbles
would not be small enough to get trapped under their shell.)
David Robinson The Discus Page
robinson at ichips_intel.com http://www.ee.pdx.edu/~davidr/