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Re: nutrient deficiency symptoms related to lighting

Sorry I didn't respond earlier, but I wanted to get a few things together 

>Date: Mon, 29 Sep 1997 09:40:00 -0400 (EDT)
>From: Jeff Dietsch <dietsch at voicenet_com>
>Subject: Rogers lights

>   That's a great case study you have there.  Well it sounds that way, I bet
>you have a great feeling of accomplishment right now eh?:)

Thanks.  I'd feel better if I knew why things changed.

>                   But the fact that they were so old, you could have lost
>one or more of the important spikes in the spectral output that left you
>with less then desirable output.  Without a good output your plants could
>suffer.  Do not let your eyes be the judge.

That seems possible, but only one of the bulbs (the Advantage X) was 
old.  The others are now 7 months old.

>2) I guess it would depend on how slow.  If your
>growth slowed then there would be less demand on the fertilizers.  And if
>one or more elements were limited the slow in growth/consumption could tip
>the scales and make excesses as apposed to limits.  So that's possible.

That was my thought as well.  But I redid my calculations and found that 
I underestimated (by about a factor of 5) the amount of growth that I could 
supply with the K and Mg I add, so if there was a nutrient deficiency 
that was changed by the slight slow-down in growth, then it probably 
wasn't K or Mg.
>  But I write this note as I am interested in see the spectral output of the
>bulbs you were using and the ones you switched to.  If you have these on the
>computer I would love a copy.  I saw that Phillips does not have them online

I put the spectra of the two Philips lights on my family web page:

http://rt66.com/~rgrmill    follow the obvious link,  OR
http://rt66.com/~rgrmill/philips/spectra.html to go directly there.

I haven't found data for the wide spectrum grolux bulb, but Richard 
Sexton discusses its light quality in his big paper at The Krib.  I'm 
still looking for the data.

>Date: Mon, 29 Sep 1997 10:38:06 -0400 (EDT)
>From: "Curtis Hoganson" <hoganson at pilot_msu.edu>
>Subject: Photoinhibition

>Because the symptoms exhibited by your plants subsided after a decrease in
>light intensity, the name of photoinhibition seems applicable.

I've read a little about photoinhibition.  My understanding is that it 
tends to become significant with light intensities that are a substantial 
fraction of full sunlight.  My tank wasn't that bright.

But you're right, the relationship between light and the accumulated
damage does give it something in common with photoinhibition.  Maybe I
should read some more into it. 

>Best regards,
>Curt Hoganson


>Date: Mon, 29 Sep 1997 22:27:32 -0500
>From: krombhol at teclink_net (Paul Krombholz)
>Subject: Re: Nutrient deficiency symptoms related to light

>Roger, this looks like like a fine opportunity to do some experiments, and
>I hope you see it that way rather than a tank full of sick plants that need
>emergency first aid, and who cares about experimenting.

Well, I kept the old lights anyway and I've given some thought to putting
them back to see what would happen.  I love experiments, but the tank in
question is in my dining room and it was starting to become an ummmm..
"aesthetic liability".  I'd really rather find some other way to do the
experiments that doesn't involve putting the lights back on the tank. 

>If it does, and you are sure you have the potassium and magnesium
>taken care of, then we may have to consider some kind of toxicity peculiar
>to that aquarium.  Toxicities  can mimic nutrient deficiencies.  I once had
>a toxicity problem that exactly mimicked calcium deficiency.

This was pretty much my best alternative theory:  the damage from oxygen 
(the toxin) mimics the symptoms of K (or maybe Mg) deficiency.  But then 
I can't really explain why the oxygen toxicity wasn't handled by the 
normal means.  Can you refresh my memory about what toxin mimiced [is 
that a word?] calcium deficiency?

>I think that if the plant in the topsoil did well, I would try a big dose
>of iron for all the plants.  That would be chelated iron and nothing else,
>just in case some of the accompanyning micronutrients in your Flora Pride
>may get so high as to be toxic.  I would get the iron level up to around
>0.3 to 0.5 PPM and see what the plants do.  I know that your symptoms don't
>resemble iron deficiency, but I am wondering if mild iron deficiency and
>bright light might combine to make the plant unable to get enough potassium
>or magnesium.  I can send you some FeDTPA, if you need some.

Thanks for the offer.  The Flora Pride is chelated iron + potassium with
no added trace elements, and when I use it at the prescribed dosage the
problem tank gets green water.  So I suspect that the iron content is high
enough to be effective.  I have a pound of FeDIPA powder that I'll get
around to using after I get a functional test kit.  Red Sea is the only Fe
test kit I've found for sale locally. 

> Paul Krombholz in Jackson, Mississippi with pleasant fall weather. 

Thanks for the suggestions.  I'll take the soil idea seriously.  It's
something I've been wanting to test for a while now. 

Roger Miller