[kekon]

As I wrote in previous posts about my "potassium problems" I still don't know what causes my plants to grow slowly and deformed. Most of my plants look like it is shown in the photo. Water parameters are as follows:

NO3 - 10 (from Ca(NO3)2 )
PO4 - 0.5..1
Ca - 22..30 (some Ca from CaCO3, some from CaSO4)
Mg - 6..7
Na - max. 6 (NaHCO3)
Cl - 5 (CaCl2)
K - dosed only during 50% WC (I dose 10 ppm NO3 from KNO3 to 50% water changed so it also adds 6.3 ppm K)
Lighting: 0.7W / L (3 x 30W 4000K + 2 x 30W 6000K + 2 x 6500K Philips bulbs)
PO4 dosed from KH2PO4; 0,25 ppm PO4 daily
NO3 2,5 ppm daily (NO3 test kit was calibrated)
Traces dosed from fertilizer which contens is similar to TMG but it contains 10 times less Molybdenum.

I tried different levels of Ca and MG but it didn't help. Each time K is more than 15..20 ppm I get severe leaves deforming and tips burning. Lover K levels (up to 10 ppm) improve the situation but only a little. In the past I used commercial NPK fertilizer containing N in urea form I didn't notice any issues with plants. The only drawback of using that NPK were thread-like algae. When switched to separate NO3, K, and PO4 dosing almost all the algae dissapeared but problems shown in the picture and stunted growth began. I'm almost giving up as I haven't managed to find what is causing the problems for many weeks New Difformis leaves grow very light-green; some are almost yellow. This is not caused by Fe deficiency. I checked it. I had some concerns about manganese deficiency so I added extra manganese but one has to wait at least a week to see the difference. I'm about to commit suicide if it doesn't help

plants that grow very well:

- cabomba caroliniana (very fast growth, deep green)
- glossostigma elatinoides (fast growth, good colors)
- zosterifolia

plants that grow very slow:

- Bacopa caroliniana (it has good colors though)
- Umbrosum (most affected as far as tips burning is concerned)
- Rotala Indica

plants that are most deformed (as shown in the photo)

- Alternatera Reineckii
- Rotala Indica

 

[Bert H]

What are your CO2 levels? I see thread algae in the pics you have provided here. I would suggest you first ascertain that your CO2 levels are adequate. After that, I would raise the NO3 to the 10-15 range, the PO4 to around 2-3.

Why are you adding CaCl2? What is your water hardness out of the tap?

 

[kekon]

I forgot to add:

Water is pure RO reconstituded by means of CaCO3, NaHCO3, CaCl2, MgSO4 and CaSO4. KH = 3. I try to keep Na max. 6 ppm and Cl max. 5 ppm. The algae you see in the pictures no longer exitsts (it was in the past). Thanks to higher PO4 and NO3 lecels I got rid of almost all algae. But I stiil have the problems described above. CO2 20..30 ppm. pH usually at 6.6

 

[MrSanders]

I would look more into what Bert suggest and check out your CO2, I bet you are a lot lower than you think. I to have a KH of 3..... and can easily run my PH down into the mid 5's and am still working on adding MORE CO2 because my fish dont seem bothered by it..... however I dont like such low PH's and do plan to raise KH to get that PH up.... but at a PH of 6.6 I would be willing to guess you are low on CO2

Also is there a reason for using RO water? espically pure? seems like that probably isnt really needed and you could make things more simple and get to the bottom of the problem more easily if you have less variables that you need to keep in line with.

 

[kekon]

The problem with tap water is that I don't know its parameters. The only ones I know are Ca & Mg. I used only RO water in the past and commercial NPK fertilizer and had only 13 ppm Ca and 4 ppm Mg and plants grew very fast and healthy. CO2 was only 12 ppm. The problem was thread algae at that time. When I replaced the NPK fertilizer with separate KNO3 and KH2PO4 the growth was stunted and leaves got twisted and deformed. So I suppose it is not problem with CO2, Ca and Mg. Probably there is missing element that was in the NPK fertilizer but I don't know what it could be.

 

[Bert H]

The problem with tap water is that I don't know its parameters.

You really don't need to know everything that is in your tap water. Provide an excess of everything your plants need and you're ok. Stunted curling leaves can be caused by a variety of factors: Ca/Mg ratios being off, too little K, micro deficient. Some plants, the ones you mention in particular, are the ones where it manifests itself more often than not.

I agree with Mr Sanders, I'm not an RO fan either. Unless there's something terribly wrong with your tap water or you're trying to grow some soft water/acid loving plants, imo, it's not worth it. You end up adding back to the water a lot of what you're taking out of it.

 

[kekon]

Using only RO water has one additional advantage for me. I can learn what plants need and what amounts of particular elements are neccesary for them. It's very interesting experiment. Using only tap water in not good as its GH = 18 and KH = 10. I used to mix tap with RO in 1:1 ratio to lower GH and KH. I realize it causes problems at the beginning. I think my problems are not caused by too little Ca, Mg or K or even Ca/Mg K/Mg ration. There is something missing or it is something toxic. I've increased trace dosage recently which helped Didiplis Diandra to have rich red color on its tops.

 

[Salt]

You are not testing your water, you are only guessing. Without testing you really have no idea what your water parameters are.

Get some quality test kits.

 

[kekon]

Well, to reconstitute RO water I use known amounts of all the elements:
CaSO4, CaCl2, CaCO3, MgSO4, NaHCO3. I can easily control all of them so there isn't an error in calculations. To measure all the amounts I use precise scale. I EMPHASIZE that the problems I've described above appeared after stopping using commercial NPK fertilizer and changing it to separate KNO3 and KH2PO4. It was the only change I made.
So, once again, the fertilizer contained something that is now missing.

 

[MrSanders]

So swich back to that fert. if thats the problem.... if your so sure its not CO2, nor does it have anything to do with using RO water and having things like Ca, Mg or K unbalanced then it would appear that you already know the answer to the reason things arnt growing?

Seems the most simply way to fix it would be to simply swich back to what you were doing before.....

 

[kekon]

If I switch to that fertilizer I will have thread algae again It cointains N in urea form.

 

[fabry]

So Kekon,
Fertilizing with urea doesn't give you the problems you have when switching to nitrogen-nitrate source.

One question:
Which micro is involved in trasformation of nitrates in a plant-usable form (that is not needed when you use nitrogen in urea or ammonium form)?

Regards.

Fabrizio.

 

[kekon]

Is it molybnenum ? As far as I know my trace fert consists only 1ppm of molybdenum. For example, TMG contains 10 times higher concentration of Mo.

 

[kekon]

I think it is Molybdenum.

 

[fabry]

Yes,
Molybdenum is needed in the first step of the conversion of nitrates into ammonium (the form of nitrogen used by plants).
If you supply nitrates without an adequate amount of molybdenum, nitrates accumulate in the leaves damaging them and giving symptoms similar to the ones you have.

Another question:
Did you notice anything strange on older leaves?

 

[kekon]

I did, but I thought it was due to K deficiency as I had dosed very small amounts of K - pinholes appeared in some leaves and some even decayed. Some older alternatera reineckii leaves have pinkish colors. I'll start dosing TMG this week and see what happens.

 

[jude_uc]

Did the commercial fertilizer you were using have an analysis of the trace elements in it? My guess is that the problem has to be in the traces. I've noticed that either by overdosing or underdosing traces, you can get serious problems. Plus, since it seems that you've check your primary and secondary nutrients, traces are really the only possiblility left. I would compare the trace element content of the commercial fertilizer with what you use now and see if there are any significant differences.

-Adam

 

[kekon]

Lately I've switched to TMG but I still have the issues. The symptomps appear on new leafs only so it can be immobile element (boron, calcium)

 

[jude_uc]

I'm sure you've already been there, but APC has a nutrient deficency gallery which could be useful for you. nutrient deficency gallery

I still imagine that traces are an issue.... You might try dosing TMG at slightly higher rates.

-Adam

 

[kekon]

Traces are not the issue. I used a fert that had 5 times more traces than TMG and it ended up with slower growth (the only good thing was little more redder colors on Didiplis Diandra). I think it can be sort of toxicity but I can find out where it comes from. Maybe it is boron deficiency but I'm completely confused...