Cardamine and Lighting

Subject: cardamine

> I just set up a discus tank...a new adventure...but i kinda went
> this blind.  I know how to keep discus...but it was not was I wa
> intending to do from the start.  One question that I have is tha
> purchased a couple bunches of cardamine from the pet shop and it
> to be melting completely!  Is this becuase of the warm water in 
> discus tank???  Everything else seems to be doing ok..except the
> cardamine :(  Any thoughts?????

If everything else is doing fine, it may very well be the heat.  
Cardamine _is_ a temperate water plant.  Even if it's not the heat 
itself, cool water plants kept in warmer water need much more of 
everything (light, CO2, trace elements) to remain healthy.

OTOH, remember that everyone's systems are slightly different. No 
one can grow everything. (particularly in the same tank)  Besides 
heat, there could be some other parameter in your tank that is 
causing the failure of one particular species if most others are 
thriving.  Water chemistry needs could be just a bit different, 
another incompatible plant could already be being used in the 
tank, etc.


Subject: What type of lighting?

> I have a 55 gal tank with 5 discus. <snip plans for planted 

> My question is:  How much and what type of lighting?  I have a 
> fluorescent fixture with 2 four foot tubes I could use.  Or I co
> with a 250 Watt high pressure sodium fixture. =20

High pressure sodium lamps are generally not the right spectrum, 
although I know there are some color corrected bulbs available 
now.  It is also hard to light a long narrow tank with a "spot" 
type light.  I would use your current fixture, and add another 
shop light behind it for a total of 4 4' bulbs. (I prefer T-8's, 
but normal T-12 bulbs will do too)

> Discus don't like that much light so I don't want to over-do it.
> do want lush growth.  I'm also concerned about the aesthetics of
> up.

Let's try once more to dispell that myth.  Discus live under the 
same sun that you and I do.  Yes. I suspect Discus in  a tank with 
no shelter and 160W of light would be a little stressed.  But what 
makes it dark in the areas that Discus inhabit? SHADE!!!  If your 
tank is planted as it should be, (heavily) you will find that the 
Discus don't mind the light at all.  They know they can get away 
from it when ever they want.  My Discus were always front and 
center in their heavily planted tank. (They don't live there any 
more because they are busy being parents) They felt no need to 
hind because they knew shelter was only inches away.

In the warmer water of a Discus tank, strong lighting (plus CO2 
and trace element supplementation) are _essential_ for healthy 
growth.  The biggest problem with planted Discus tanks is feeding 
the fish properly and still keeping phospahte levels low enough to 
avoid algae problems.  I found with 4 Discus in a 55G this was a 
big issue, (I changed 50% of the water twice a week) 5 would be 
that much worse.

Karen Randall
Aquatic Gardeners Assoc.
Boston, MA