Calcium Deficiency, ...or something else???

[Milan]

Hi All,
I need help with my plants. In the last few days leaves on some plants (ie. Hygr. Polysperma, Bacopa Car.) became shrunken, cupped or curled if you wish (see the pictures below), so I suspected the Calcium deficiency, according to what I read about it on the net (including this site). Today I went to a LFS and bought a Calcium test, and measured 60 mg/l Ca++. Now I'm completely confused ... This should be enough!

Here are the complete (available) water parameters:
NO3 = 5 ppm
PO4 = 0.5 ppm
GH = 10.8 dGH
KH = 5.6 dGH
pH = 7.1
CA++ = 60 ppm

Other Info:
Tank - 29 g (click to see)
Light - 65W 6700K
DIY CO2

So far I've been fertilizing with K2SO4 only + TE, since NO3 and PO4 have been always on targets. Actually I increased the dosing of K since couple weeks ago when I had potassium deficiency. Current dosing is @ 2 ppm/day. Now, I'm wondering if too much K can do this? According to any reference I have come across, there is no harm in K overdosing. And by the look of it, ... Is the test I bought fooling me, or I'm badly missing something?

There are some other observations as well, which may point my thoughts in some direction(s) ... Let me share them with you:

1. Lately, since ~ 2 months ago, there are snails in the tank (taking Ca for their shells, perhaps?). I think they are ramshorns, but they don't get bigger than 1/8" (lack of Ca again?)

2. Look at the stem of the Water Sprite (Ceratopteris thalictroides). It's rotting. It happens on another one in the tank too. New growth is OK. Could this be related?

Any help ????

 

[malkore]

You have plenty of hardness...Ca isn't the issue unless you've been grossly overdosing K.

Are you dosing traces?

IMO nitrates should be at least 10 and phosphates at least 1-1.5ppm

 

[Milan]

Ca isn't the issue unless you've been grossly overdosing K.

Thanks Malkore,
I think I am overdosing K, but what's "grossly"? It's @ the rate of about 2ppm/day. Every reference I have come across says there is no harm in overdosing K. No mentioning of grossly, moderate, little ...

 

[Hoovercat]

Grossly overdosing K can interfere with Ca uptake.

 

[Milan]

Sorry, forgot to mention TE's. Yes, I'm adding traces as well. They are Chelated Trace Element Mix @ (7% Fe, 1.3% B, 2% Mn, 0.06% Mo, 0.4% Zn, 0.1% Cu).

Would too much K affect Ca uptake, if I get it right ...?

 

[Milan]

Grossly overdosing K can interfere with Ca uptake.

Sorry, seems like we were posting at the same time. So that's the catch ... Thanks a lot.

Out of curiosity, what's the explanation of this..?

 

[czcz]

14ppm K isn't too much, as 20ppm is considered a good target. (I don't understand the why of its relationship with Ca either.) Photos do appear to fit the description for Ca deficiency but I have never seen it in person. FWIW, I would dose Ca despite tests, as it follows using plants as indicators and it's the only way to know for sure.

 

[malkore]

I don't think you're over dosing K at those levels. By grossly, I'm talking something like 2x to 3x the 20ppm target, and really it's gonna be noticed most in a softer water tank.

 

[travis simonson]

You've got an interesting issue there. I'm with malkore on the nitrates, try bringing them up to 10-15 ppm to see if things improve. I think PO4 at .5 without CO2 should be fine. Always look for deficiencies in the macro (NPK) nutrients and Fe before suspecting something as minor as Ca or Mg. Your lighting may be driving uptake of N and, without a highly accurate test kit, 5 ppm of NO3 might actually be even less. Do you have any problems with algae?

 

[Milan]

Do you have any problems with algae?

Thanks Travis,
Not any major issues with them. There are some long thread algae which I don't loose my sleep over because they are easy to remove mechanically. I believe they indicate excess of Fe, .. right? So, that narrows it down to NPK ...

Anyhow, I did a 50% WC, and from now on, I'm adding standard solution fertilizer (0.75-0.25-1.00), 5ml every second day, and TE's on alternate days. CO2 is a little bit up, @ about 19 ppm. Seems like the pH can't go down any further. My tap water is @ 8.0. Would bringing down pH help, ie using peat granules in the filter? Would that pull the KH down as well?

I'll see if this turns out any good ....