Mercury vapor light & algae eaters (fwd)

---------- Forwarded message ----------
From: Claes.Anglefalk at epk_ericsson.se (Claes Anglefalk)
Date: Wed, 4 Dec 1996 11:56:12 +0100
Message-Id: <199612041056.LAA24136@hm133.ericsson.se>
To: aquatic-plants at actwin_com
Subject: Mercury vapour light and algae eaters
X-Sun-Charset: US-ASCII

Hello everybody

I read in the last month's messages about mercury vapour light.
I got the general impression that mercury vapour light should
be bad for plants due the bad spectrum they perform. The
spectrum was said to contain wavelenghts almost only in the
blue part of the visible spectrum.
I have serious difficulty to really agree with that for some

1. Fluorescent tubes are, as you all know, available in many
different colour types. Some of them are good for aquarium plants
and some of them are bad, like maybe "cold white".
Mercury vapour bulbs are also available in several colour types,
at least in Sweden where I live.
There is one type, probably cold white, mercury bulbs. They
are used for example in street lights in Sweden. This one
looks a bit blueish when it shines. If it is this colour type
that was considered in the discussions I can agree with you.
I would defenitely not like that colour above my tank.
However, There are also warm white mercury bulbs and if you
put them over a tank they look like a warm white fluorescent,
though the mercury bulb has much, much more intensity.
There are even bulbs specially made for aquarium plants. The
German company Dennerle sells one with a colour type called
"TROCAL", more about that one below.

2. At least in Sweden in companies, schools etc mercury
vapour light is frequently used above plants placed out of
range from daylight (basements etc). These plants do all look
very healthy and fine. Do you think the blueish street light
bulb is used here? Defenitely not. Some kind of warm white
bulb is of course used. I have not checked which bulbs they
use. The point is however that the plants are doing very well.

3. Now we are approaching my aquarium. What do I use for my
I have a 310 l aquarium (125x50x50) cm. About two months ago
I changed the light to mercury vapour light. Above the tank
are now two lighting fittings for Mercury bulbs. In the fittings
I use 125 W Dennerle bulbs. The bulb is the one
I mentioned above (TROCAL). The TROCAL bulb is supposed to
immitate the fluorescent tube from Dennerle with the same name,
but the mercury light is much stronger.
The TROCAL colour is said to be specially good for aquarium
plants. Since Dennerle do not seem to do anything else than
deal with products for aquarium plants, I took a chance and
bought the mercury light fittings with bulbs.
How did it work out then? Well, in the first week nothing
particular happened (the plants were probably adapting to the
new strong light). After that the plants started to grow like
I have never seen before. Even Red Cabomba ( Cabomba
Piauhyensis) and Rotala Macranda is now growing very good.
The colour of the light in the aquarium looks very nice. No
strange colour of the fishes or the plants at all. I like very
much the shadow play that appear with only two bulbs instead
of long fluorescent tubes. I am very satisfied and I do not
think that mercury vapour light is too bad at all.

The question is now why I changed to mercury vapour light.
Well, since my tank is quite deep I would have needed four
36 W fluorescent tubes. Nice tubes (TROCAL, TRITON etc) are
expensive and not to mention the price of the fittings adapted
to four tubes. Furthermore the mercury vapour bulb last at
least twice as long as fluorescent tubes. It was simply
cheaper with mercury vapour light in the long run.
There is another strong reason for mercury vapour light:
The fitting is hanging over the tank. Then it is a lot easier
to work with the plants. The other type of fitting that is
hanging over the tank is MH fittings. I am sure they work very
fine but in Sweden they are that expensive that you can just
forget all about them.

I know that it is quite common in germany with mercury Vapour
light and some information about them can be found at Dupla's
or Dennerles homepages.

Finally I have a question for anyone with knowledge about
algae eaters:

Which Peckoltia is best to use, Pulcher or Vittata?
Are they agressive? How effective are they compared
to Ancistrus? Perhaps someone has a good webspot about
these fishes (Ancistrus and Peckoltia)

I would also like to thank Liisa Saracontu for a superb article
about the Siamese algae eater. I realized that my tank
had contained the false Siamese algae eater for a year. The
mistake is now corrected.

I hope this mail arrives correctly. I have never tried this
mail list before.

Note: I have nothing to do with certain german companies. I am
just a satisfied customer.

Have a nice day