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Re: Aquatic Plants Digest V4 #222


    If what you mean by 'reverse photoperiod' is to have lights on for algae
>scrubbers at night while the main tank is lighted during the day, I think I 
>know the
>answer.  It has nothing to do with nitrogen uptake. 

>    However, I suspect that it would not have much application to planted tanks.
>Most freshwater plants are used to pH and alkalinity swings.
>Diana Walstad

Thanks. This what I suspected..........
The reef folks trying to apply their ideas directly to planted tanks which
aren't applicable often. 

And this makes sense from natural lake and reefs also. There are those big
daily PH swings in ponds and almost none if any on reefs. But rivers and
streams don't have much PH swing though............crypts come to mind
but many FW plants are very adaptable so they can handle both well. 

Nitrogen uptake seems to be of little importance on this Reverse photo
period notion. So as was suggested that plants suppress their N uptake
during "day" to spend their energy on sugar production would it not be
preferable to add the Macro element N, say in the form KNO3, to the water
column at night then? With soil/substrate rich tanks..........as you well
know know...........the plants always have access to these nutrients so they
can use them when they need they them. Comments?  Would this help a planted
tank by adding KNO3 at night? Perhaps some trace elements as well?
Tom Barr