I knew that Kekon was preparing something in the background. Always interesting and informative, I follow your threads with attention, thanks for your work!
I just want to share an experiment I realize with my thread ... Survey of 33 gal on 32 weeks... 11x17 inches, 528k, pdf...
Link at : http://www.grafcomm.ca/33gal.pdf
This survey of water parameters on 33 weeks is compare to the general health of plants in this 33 gal tank.
— Anubias nana
— Ludwigia repens
— Rotala indica
— Small sword plants
I’m still looking at this compilation and probably come with some conclusion later, or maybe some of you out there can share what they think....
Anyway, I just did an average of the concentration of nutrients in the 9 weeks where the plants look there best.
It should give an idea of the optimum concentration for this particular setup.
KH = 18.2 mg/l
GH = 148 mg/l
Ca = 45.5 mg/l
Mg = 12 mg/l
NO3 = 7.1 mg/l
P04 = .7 mg/l
K = 16.5 mg/l add every week
Fe = .33 mg/l
Personally I think that a level of Ca between 40 to 60 mg/l are OK
Surprisingly it seem that the ratio between Mg and Ca do not seem to be the only culprit in Ca absorption. Anyway I beleive that the Mg level itself is more important that the ratio of Ca/mg
My main concern was to obtain fast growing plants like Elodea and Rotala to thrive and the Ludwigia to not be crinkled and grow reasonably fast ( 2 to 3 inches a week)
The Ludwigia problem seems to be somekind of Ca absorption limitation.