Stubborn orange L. arcuata

["Carlos Sanchez" <tsunamicarlos at hotmail_com>]

Hi everyone,

   I recently setup a 20 gallon long aquarium about three weeks
ago and received some cuttings of Ludwigia arcuata from
a fellow hobbyist. They were blood red - beautiful color! In my tank,
they promptly turned orange with lime green stems. I also got
some emersed cuttings from another hobbyist, and those transformed
into a submersed state... also with orange leaves.
   I've been struggling to get them to turn red. Nothing seems to
be working!

What I've tried:

Attempt #1: Focusing a 6400k 13 watt power compact right over them.
No effect on color. Faster growth. (total lighting over 20g long is
3x13 watt PC bulbs (mix of 6400k and 5000k), 2x20 watt GE Aqua Rays 
Fresh/Salt for a total of 79 watts or 3.95 w/g).

Attempt #2: Increasing Fe, traces, and K. I now add 6 ml Flourish
Fe 3x a week, 5 mL Flourish trace 3x a week, and add enough K to
raise the tank's K level by 20 ppm every week. Hmm. Green plants
look greener. Ludwigia glandulosa more vibrant. L. arcuata still
orange. :)

Attempt #3: Get NO3 levels really low to 3-5 ppm (initial level at 8-10 ppm) 
and upping PO4 levels to around 0.5-0.8 ppm. Been like this for about a 
week. No effect on the L. arcuata's color. NO3 levels measured with a 
LaMotte NO3-N test kit and PO4 with a Seachem Phosphate test kit. I found 
this a bit strange, since I could get Ludwigia repens brick red with this 
N-P regime in another aquarium.

Other tank specs, if it helps:
Pressurized CO2 (maintain CO2 levels at 30-35 ppm)
Bioload: ramshorn snails and 6 amano shrimp (very light)
Temperature: 75-78 F
Very little algae, anywhere

In this tank, it's apparently a trend since the R. wallichii and
Ludwigia brevipes are practically green as well. All plants growing rapidly 
except for R. wallichii which is a bit sickly and tends to stunt a lot. 
Hottonia, Ammania gracilis, Ludwigia glandulosa, and
Potamatogen gayi are thriving. What am I doing wrong here? How
do I get the Ludwigia arcuata to turn the red color I originally
got it in (which was like Nature Aquarium World's L. arcuata)? I'm
running out of ideas. :)

Carlos



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