Help! My snails aren't happy

[Florin Ilia]

What kind of iron reading do you get an hour after dosing?

Tomorrow is micro day and I will try to test 1h after dosing.

I would recommend increasing the frequency of your 13% EDTA Iron dosing.

Alright.

Your description and photo of the snail suggests (strongly) a Calcium deficiency that is being corrected.

Based on the all the information I would say a toxin that disrupts the snails ability to use Calcium and is apparently removed by the activated charcoal.

Let me add some new info:
- I have 2 other tanks, one is a 10l shrimp picotank and the other is a 35l low-tech planted tank with a betta
- there are snails in both other tanks; they show SOME shell deterioration but they don't look sick - they are active, they reproduce, they never burrow
- in light of the above I thought I'd summarize the things that the main tank has and the others don't have:
--- substrate (ADA AS New in main tank, other substrates in the others)
--- rocks (the main tank has, STRIKE THAT, had a couple of "Ryuoh" stones); I removed them while writing this post; see pic below for appearance; they don't scratch easily; they fizzle energetically in contact with vinegar
--- fertilization; I guess this could be a source for something toxic; I could buy a new batch from a totally differnt source (my original one was www.greenleafaquariums.com/ iirc)

Why did I not mention all these things from the beginning? Slow thinking I guess, sorry.

The stones (below, the wet ones, I just removed from the tank; above, dry, a stone from the same batch, it was removed from the tank a while ago:

[Florin Ilia]

CO₂ is another difference.

[Biollante]

Hi Florin,

I cannot believe I didn’t ask you about the rocks, folks are always getting angry when I suggest one of those precious rocks may be the problem.



It would be interesting to drop those rocks in a bucket with dechlorinated water or perhaps water from one of the other tanks.

Add a couple of snails perhaps from another tank and see what happens.


I have suspicions about Ryuoh stone, Seiryu Stone, Maten stones, Shou stones and so forth…

• Obviously metasedimentary rock, my guess, calcareous siltstone (claystone?) the problem being what the volcanic material trapped.
• I am thinking these rocks are kind of a time-release version of Russian roulette in our aquariums.
  

The added CO₂ certainly could be a difference, the lower pH dissolving the rock more quickly.


You think the vinegar was interesting pour a little hydrochloric acid and see what happens… Be careful.


Until you confirm the rocks as the cause I would still be wary of the tap water,
it is also possible the CO₂ and the lowered pH is exaggerating or accelerating the toxic effects and
they are simply occurring at a slower rate in the non-CO₂ tanks.


I seriously doubt the fertilizers from a reputable group as Green Leaf Aquariums would be the problem.


Biollante

[Florin Ilia]

Today I dosed my usual microferts dose and I added the 13% Fe EDTA.

My microferts solution is made of 2 teaspoons of Plantprod Chelated Micronutrient Mix to which I added DI water up to a volume of 448ml and a couple capfuls of Seachem Excel. One dose of micros is 7ml of this solution and I add it 3x /week. I think this means
2 tsp x 7/448 = 1/32 tsp 3x /week (I am ignoring the dilution from Excel)

To this I added today 1/32 tsp of 13% EDTA Fe.

Let me try to calculate what that this dose means. I would be surprised if I got this right, though

The exact composition of that micronutrient mix is a bit of a mistery in the sense that I couldn't find a guaranteed analysis of it. I always assumed it is "like" CSM-B but with a Fe/B ratio which makes adding B unnecessary. Unofficially I found this composition:
Mn 2.00%
Fe 7.00%
Zn 0.40%
Cu 0.10%
B 1.30%
Mo 0.06%

Assuming this is correct and that a teaspoon of this mix weighs 5 grams, then:
5g / 32 * 7% = ~11mg Fe in one PPCMNM dose
5g / 32 * 13% = ~20mg Fe in one 13% EDTA Fe dose
Total 31 mg Fe.

Water volume in my tank is about 50l (considering the tank and the oversized canister filter) so the Fe concentration that I added today is about 0.62 mg/l.

Two hours after dosing I measured Iron and I had 0.36 mg/l. That looks like a big discrepancy.
- either my plants eat iron like candy
- or something in my tank eats the Fe (like you said, it reacts with something)
- or the composition of PPCMNM is not what I think it is
- or my calculations above are wrong
- or my Fe measurement is wrong
- or there's some other cause that I can't figure out now
- or a combination of the above.

I am clearly very close to solving this mystery

Florin

PS One more hour and the concentration is 0.27 mg/l. It does seem to go away fast. I will measure again tonight.

PPS The composition of PPCMNM that I posted above seems to be correct. The online store that I bought it from posts this in the product desctiption:

Plant-Prod Chelated Micronutrient Mix is also referred to as Trace. It contains: Iron-2.1ppm, Manganese-0.6ppm, Zinc-0.12ppm, Copper-0.03ppm, Boron-0.39ppm, and Molybdenum-0.018ppm.

On the box I received it in there is a big handwritten label that says "3 grams per 100l of water". If I apply the composition above to this indication, I end up with EXACTLY the concentrations from the product description.

[Florin Ilia]

PPPS I weighed 1 tsp of PPCMNM and it's about 4.5g instead of the 5g assumed. The 13% EDTA Fe is about 4.85 g/tsp. The added precision means that my theoretical dose was 0.59 mg/l instead of 0.62 - the problem remains the same.

[Florin Ilia]

I measured Iron again one hour after the last measurement, expecting to find something like 0.19 ppm. Surprise! It was 0.40 ppm.

9:45 dosing 0.59 ppm
11:45 measured 0.36 ppm
12:45 measured 0.27 ppm
13:45 measured 0.40 ppm

Looks like measurement #2 is suspicious.

I cannot vouch for my measurement skills, I have no lab training at all - I just bought an expensive device and I follow the written instructions. Oh well. Like I said, I will measure again tonight.

[Biollante]

Hi Florin,

Welcome to the club! After the first blush of excitement, most of us find the "testing thing" is far trickier than we ever imagined! In testing, we learn the difference between “accuracy” and “precision.”

• Once our mechanics are passable, it occurs to us that we may not actually be measuring what we thought we were.

I found that by making 1 or 10% solutions of whatever I am learning to measure and then by serial dilution reduce them to desired concentrations.

• We get so used to talking about “parts-per-million” and tenths of “parts-per-million” that
  
• sometimes we forget how small these quantities are
  
  
  • in relation to the total volumes being measured.
    
  
  
• It is no different than trying to weigh ½ gram of salts using a 60-gram beaker,
  
  
  • the large difference between the container and the substance to be weighed
    
  • adds to the uncertainty of our result, no matter how accurate the scale.
    
  
  

For now as a practical matter,

• I recommend you double your iron dosing and
  
• for the moment consider testing a separate hobby.
  

I think you are risking being lost in the numbers.


There is a reason the Johann Wolfgang von Goethe quote appears in my signature, it sums up my experience.


Biollante

[Florin Ilia]

• for the moment consider testing a separate hobby.
  

Wise words.

Actually this is how I look at it, a parallel hobby.

I just want to play scientist for a few hours per month.

If you follow that link you'll see that (at least at face value) I'm not one of those folks blinded by numbers.

Also, 20+ years in the software business taught me that there's just a few ways to get something right and infinite ways to get it wrong. I am always skeptical of my own results. When in doubt, I assume I screwed something up

This being said, I wouldn't mind this parallel hobby to actually help me diagnose something once in a while

I measured my Iron again, 3 times (with the DR/890, the Hanna is out of reagents). The values were 0.05, 0.02 and 0.04 ppm total Iron. The lack of amber coloration was visible to the naked eye. The DR/890 reagent expires in sep 2014. The method I used is Hach method 8008. It does say that it needs digestion prior to analysis but in previous tests, the DR/890 and the Hanna checker for Iron agreed very closely (within a few hundreths of ppm) so I assumed digestion is not necessary in my case.

No matter if the result is accurate or not, if it's at least proportional to the actual Iron content then it shows an Iron consumption higher than I would expect.

As for increasing the dosage, would you recommend doubling the dose of PPCMNM, the 13% EDTA Fe or both?

Thanks for all the advice,

Florin

[Biollante]

Hi Florin,


The “needs digestion prior to analysis” thing applies mainly to wastewater testing,

• situations where there may be considerable amounts of organic and complexing materials that “hide” the metal.
  
• In these circumstances, it would not matter what test set you were using.
  

In addition, before the “digestion” step you would need to “homogenize” the sample and set the pH before and after digestion.

• I homogenize my samples, but then I am a bit of an idiot.
  
• I have done the digestion and pH setting, but found no real difference in aquarium or aquaponic conditions.
  

Hunting unknown metals, I might recommend going to the extra trouble.

• If high dissolved organic material were the confounding or suspected factor,
  
• treating the tank with Potassium permanganate at 2-ppm
  
  
  • until the water remains a light pink 4 hours would oxidize the excess organic material.
    

Unfortunately, there are also issues around sampling location and technique that can also be a factor.

I would double up the 13% EDTA Fe, perhaps simply go to everyday dosing.


Biollante

[Florin Ilia]

I would double up the 13% EDTA Fe, perhaps simply go to everyday dosing.

OK, that's easy.

Just a question though: won't the Fe react with the phosphate from my macro dosing? Or from the tank? In fact, couldn't PO₄ be the thief of my hard earned Iron?

As for digestion and homogenization - I'm not saying I won't learn to do them, but can we please exhaust the other options first?