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Leaf deformation = calcium deficiency?

I recently upped the lighting available to one of my 20 gallon plant tanks 
to ~3W per gallon 5000K PCF (plus a good reflector) and I'm seeing two 
nutrient deficiencies develop.  One deficiency is phosphorus which I was 
expecting and am prepared for (although it struck much faster than I'd 
anticipated), but I'm also seeing signs of calcium deficiency---that is 
curling, cupping and twisting of leaves which in this case is most evident 
in Echinodorus spp, the lone exception being tenellus.  I'm curious about 
this occurrence because my tap water has a hardness of 6 dGH.  I've not 
really noticed this deficiency in any of my tanks before, but I've never 
had one this well lit.  I also recently redid lighting over another 20 
gallon using 4x15W NO fluorescent (no decent reflector) and it is also now 
showing similar signs of trouble but not as extreme as in the PCF lit tank.

Before I pose my questions, here's the stats of the tank in question should 
it prove helpful:

--Volume: 20 gallons
--Hardness:  6 dGH
--Alkalinity:  4 dKH
--pH: 6.6-6.8
--NO3: ~10ppm on avg
--PO4: 0.05ppm or less from tap...I dose for ~0.5ppm in tank.
--DIY yeast culture CO2 generator.  Refreshed every 5 days.
--Transient livestock (in process of acquiring "permanent" stock).
   Tank currently only holds 6 Otocinclus and 5 C. japonica.
--Filtration is bio/mech only...no chemical filtration.  Canister.
--Substrate:  3" Flourite covering 1" peat/soil (backyard brand ;-).
   It's been established for about 8 months.
--Nutrient dosing: KNO3, Flourish, Flourish K+, Flourish Iron,
   occasional addition of 13-4-5 houseplant spikes for root
   feeders.  I recently began adding PO4 via a water soluble
   African Violet fert.
--Light cycle: 12 hrs of 1x55W 5000K PCF.
--Plant spp: A.b. nana, E.p. tropica, E. tenellus, an
   unidentified sword, Cardamine, V. spiralis, Xmas moss,
   Java moss, Windelov and narrow-leaf Java Fern, assorted
   Crypt spp.
--Maintenance:  75% water change once a week with pruning
   beforehand.  Hardly any algae to clean off--no visible mats,
   just hair here and there when I let P or N or CO2 get weak.
   Canister filter gets cleaned every 3-4 mos or as needed.
--Ornaments: wood and river rock from local river.

Some details on dosing:  It's pearl city in this tank all day every day, so 
I reckon a lot of stuff's getting used up.  I have to check daily to 
maintain good levels of NO3 and PO4 and adjust dosing to maintain 
established ranges.  I add 0.5 ml of traces daily (Flourish).  If either N, 
P, or CO2 gets out of wack (rare these days fortunately), I back off traces 
until levels are decent again.  K is added after each water change to 
approximate 25-30ppm.  I pulse additional iron every second day throughout 
the week.  I add fert spikes to the substrate sporadically.  The African 
Violet fert is new to the regimen and I'm not sure how it'll work out long 
term...so far, so good, but it's still early.

Ok, I've hopefully presented a decent overview of tank conditions.  Now, my 
questions are:

How likely is it that the Ca/Mg ratio is far enough off at this level of 
hardness (6 dGH) that I would see calcium deficiency?

Could the lack or excess of another element be preventing the uptake of 
Ca?  Is the prior lack of PO4 a possible cause?

Could the leaf deformation be due to a deficiency other than Ca or caused 
by something non-nutrient related?

Finally, if Ca is indeed the problem, what substance are you folks using 
for efficient Ca dosing?

Any and all ideas and advice are very welcome (even those not related to 
the topic).  I'm on the verge of checking off the last of my plant nutrient 
tribulations after a long, hard road and I'm hoping y'all can help.  Well, 
it's bedtime for me, so see y'all in the morning :-)

Chuck Huffine
Knoxville, Tennessee  USA
mailto:grendel at usit_net