Re: Aquatic Plants Digest V1 #72

>From: nguyenh at nosc_mil (Hoa G. Nguyen)
>Date: Wed, 15 Nov 95 10:06:55 PST
>Subject: T8 & T12 + decalcification?
>I have been following the thread on T8 and T12 bulbs, and have a question.
>My favorite bulbs, the PennPlax Ultra Tri Lux 40W bulbs, are 1.25" in
>diameter.  This is right between a T8 and a T12.  What is it then?  A while
>ago, I went shopping for electronic ballasts, and talked to a few people at
>industrial lighting places.  They said that I have to match the ballast to
>the bulb.  That is, buy a T12 ballast for a T12 bulb, etc.  I don't know
>what the Ultra Tri Lux is, but I settled for a T12 ballast.  Is this okay?
>Does anyone know?
>It's working okay, but I just wonder about any life-shortening effect.
It is obviously a T10. :-)  Seriously, I would try to find out what ballast
the manufacturer, PennPlax, recommends.

>On another matter, I decided I've had enough with weekly pruning of my
>plants (enough credit at the fish store to last a while), so I disconnected
>my CO2 injection last week, hoping to slow down the growth.  The plants are
>still okay, but I have noticed that the Anacharis have formed a sandy layer
>on the leaves.  Is this the decalcification effect?  And will it be bad? I
>have been monitoring the pH, and it's about stable at 7.6 (tap water here is
>8.1 pH, 18dGH, 8.4 dKH).  pH was around 7.2 with CO2 injection.  What else
>should I do to balance things out if I don't want the plants to grow so
>fast?  Reduce lighting duration?  Right now it's about 10 hours of 120W (80
>bright Watts of Ultra TriLux, plus 40 dimmer Watts of Vita-Lite, on 75
>gallon aquarium) plus 3/4 hour of sunrise/sunset periods on each end (40W).
The sandy layer on the leaves is calcium carbonate.  Anacharis ( called
Egeria densa in Mühlberg.s book) is capable of utilizing the bicarbonate
ion.  It takes in bicarbonate, HCO3-, keeps the CO2, and leaves behind OH-.
In strong light, this process can create enough alkalinity at the leaf
surface to precipitate calcium carbonate, CaCO3.  As long as your pH is OK,
I wouldn't worry, but you should keep close watch on the pH.  I once saw
that my zebra fish in a tank with 3 T12 fluorescents and a lot of Anacharis
looked a little sick.  I took the pH and found it to be 9.6.  I added some
CO2 and the zebras looked a lot happier.  Plants like Elodea, Najas,
Vallisneria, and ceratophyllum that can utilize the bicarbonate ion can
raise the pH in well-lit aquaria to almost lethal levels for fish.

>BTW, what is the scientific name for Anacharis sold in the Western United
>States?  I can't decide if it's Egeria densa or Elodea canadensis.
It is probably the latter.  Elodea canadensis is a much smaller plant with
leaves usually less than 1 cm. long.

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174