[shalu]

Rotala macrandra var Narrow Leaf will grow in pretty much the same conditions as Rotala macrandra, Rotala wallichii, et al. Give them moderate NO3 (5-10ppm), high PO4 (1.5-2ppm), plenty of light, and plenty of iron (Flourish/TMG). They also seem to like water on the softer side (doesn't have to be SOFT, but not the more extreme GH 12-15+).

If Rotala magenta really does not work out, a more suitable replacement would be Ludwigia arcuata (as they have similar leaf texture and color) which is much easier to grow.

Carlos

My experience has been to the contrary as far as low GH goes. Until recently I had no luck growing Rotala macrandra or Rotala magenta. The new growth tips always stunt and the small new leaves are twisted. Even though my tap GH=8, I thought I might try more Ca just in case because the symptoms do look like calcium deficiency. Well, after a month of CaCl2 addition (GH to 13), my rotala macrandra is drop dead gorgeous, blood red, growing/branching like crazy. Rotala magenta is doing much better as well.

 

[shalu]

Perhaps Ca/Mg relationship is the culprit and not actual hardness? Hmm.

Carlos

That's what I was thinking as well. Separate accurate measurements of Ca/Mg require expensive kits, so I am not sure what exactly the values are in my tap. I am also doing an experiment with partial RO with small Ca addition to see how it turns out for me, so it will be softer water with higher Ca/Mg ratio(actually it might be any other elements in tap water, like Ca/TDS? because some people report Ca/K also matters, but not in my case). But it is a low tech tank w/o CO2 so it would take a long time to see the effects.

 

[shalu]

Hi shalu

Surely you already have a GH kit, so the only one you would need to add is a $6 Ca test kit. You can get Mg concentration by testing for GH and Ca, then calculating the Mg.

Water hardness, magnesium and calcium article

Edward

The only problem is, my $6 Ca test kit(AP one I think) was for SALT water, and I know for sure its reading is way off for freshwater, because I did an experiment by adding NaCl into the water to mimic salt water to some degree, and Ca reading is very different. In addition, it is in increments of 20 ppm. So combined resolution of GH(1 deg) and Ca makes accurate determination almost impossible. Or can you suggest a good, cheap Ca test kit for freshwater?