Calling all chemists

[papa_c]

Here's a question which takes me back to O'level Chemistry lessons, and for the youngsters out there that's the same as GCSE's!

When mixing up my EI macro/micro solutions and also RO remineralisation solution, I dissolve the minerals in fairly RO warm water, not boiling but warmed at a guess to 65c in a kettle.

Does using this method alter the chemical compounds and render them useless for ferts and remineralisation?

 

[zozo]

I'm not a chemist, but a old fashion educated plummer.. We had to know that Calcium / Magnesium deposites as scale from 60° C and up.
If this is a permanent miniral binding i doubt.. But most ferts in sulotion say on the lable store cool and dark.. So likely temp and light will make it crystalize..
I wouldn't go anything higher than lukewarm..

 

[dw1305]

Hi all,

When mixing up my EI macro/micro solutions and also RO remineralisation solution, I dissolve the minerals in fairly RO warm water, not boiling but warmed at a guess to 65c in a kettle.

Does using this method alter the chemical compounds and render them useless for ferts and remineralisation?

No, you are fine.

Virtually all the compounds used in plant fertilisers are soluble (they dissolve into ions, and plants can only take up ions), and solubility increases with increasing temperature.

If you make up very strong solutions you could run into problems with the <"common-ion"> effect as the solution cools.

We had to know that Calcium / Magnesium deposites as scale from 60° C and up.

That is slightly different, it occurs because carbonates (as HCO3-) are only soluble in equilibrium with CO2, and gases are less soluble at higher temperatures.

As the temperatures rises CO2 comes out of solution, which means that less HCO3- can remain in solution and it precipitates out as insoluble calcium and magnesium carbonates (multivalent carbonates are less soluble than monovalent ones, again via the common ion effect).

cheers Darrel

 

[zozo]

Thanks Darrel, that makes perfect sense.. Along the way it explaines why there is less deposite on the glass in high tech tanks..
Slowly more and more get my head around the whole HCO3 / CO2 relation..

 

[dw1305]

Hi all,

Along the way it explaines why there is less deposite on the glass in high tech tanks..

I think it does.

The strange this is that I knew that carbonates are less soluble at higher temperatures (nearly all other salts are more soluble at higher temperatures) but until I joined this forum, and was introduced to pressurized CO2 and 4dKH drop checkers, I didn't know why (although I should have done).

cheers Darrel

 

[zozo]

I guess there is a lot more we maybe should or could know and we just do not think about it because there is no pragmatic reason to.

 

[Ed.Junior]

I thought EDTA itself could break down. EDTA solutions are stored at low temperatures to prolong its life (months) but EDTA will break in hours at 150° C.

Yeah, crazy higher, kind of apples and oranges.

I guess you could prepare an acidic solution, ~pH 6, add KH2PO4 and your Fe/Trace mix. Boil it. If the chelator breaks you should have a precipitation on the bottom.

I have no idea if this actually proves it...

For the other salts there is no issue.

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[dw1305]

Hi all,

I thought EDTA itself could break down. EDTA solutions are stored at low temperatures to prolong its life (months) but EDTA will break in hours at 150° C.

EDTA would be an exception to the "soluble", that was actually why I wrote "virtually all". I thought that EDTA was thermally stable until you get to just over 100°C, but I don't have a reference for that.

One thing I have just found out is that if you do make bulk solutions EDTA, that you are going to store over more than ~12 months, you should store it in an opaque plastic bottle.

cheers Darrel

 

[Ed.Junior]

Hi all,EDTA would be an exception to the "soluble", that was actually why I wrote "virtually all". I thought that EDTA was thermally stable until you get to just over 100°C, but I don't have a reference for that.

One thing I have just found out is that if you do make bulk solutions EDTA, that you are going to store over more than ~12 months, you should store it in an opaque plastic bottle.

cheers Darrel

True about opaque bottles, as light breaks it.

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[papa_c]

All, thanks for your comments and contribution, it makes interesting reading.

So my dilemma continues as the hot water dissolving is not my issue, something has had a negative effect on the plant grow I have had a sudden lose off leaves on Hygrophilla Compacta which was growing nicely and I am none the wiser, the only change made was to the EI solution increasing KH2PO4 from 15g to 20g, mixing this with 1000ml of water and dosing 90ml solution into a 200l tank.

Full EI mix is as follows

Macro 35gKNO3, 2g KH2PO4, 120G MGSO2. 1000ml mix 90ml dosed days 1, 3, 5
Micro 15g Trace 1000ml mix 90ml dosed days 2, 4, 6

CO2 dilution remains the same as measured by a pH probe in water continuously and outputting a measurement every 30 minutes, lighting period is the same.

Any ideas or suggestion?

 

[Daveslaney]

Could be the dry salts disolving into solution is the problem?
You could split your MGS02 60g in Macro 60g in micro see if this makes a diff. As you say all youve done is increase the content of the salts in your macro mix with the po4.

 

[Ed.Junior]

Mg and Ca should go with the water change. They are forming the basic parameters, setting your GH, and they are not consumed the same way the macros are.

Never used Mg hyposulphite before, only sulphate, as in the usual epsom salt. I would definitely not mix that with the macros, in the same bottle.

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[Daveslaney]

Why? Most EI recipes the MG is in the Macros?
Must admit i have only used Epsom salts too not mgso2.

 

[roadmaster]

Mg is in trace mix CSM+B I use along with that that might be present in source water.
I use a macro/micro mix www.aquariumfertilizer.com in my low tech and the mix has all macros and micros minus the phosphate which my fish food's appear to provide at sufficient level's.

 

[Ed.Junior]

Why? Most EI recipes the MG is in the Macros?
Must admit i have only used Epsom salts too not mgso2.

Mg and Ca are the main elements composing GH. When you do the water change, you adjust your GH to the desired levels, by adding Epsom Salts, CaCl2, or Seachem Equilibrium, which among another things, like Potassium, will add Mg and Ca.

This is your basic water parameters, plants will not consume Ca and Mg like they do N, P, K or Fe. You adjust to your plant needs and leave it. This is to create the right environment for your plants. It will not get consumed in a couple weeks to an ammount that matters.

Most EI "recipes", IME, do not mix MgSO4 into the Macros, but some do add it to the traces, but in very little amounts. One reason to avoid doing so is that every time you would dose macros with MgSO4 you would raise the water hardness.

All that being said, I tried it in the past, just because I was lazy and wanted to avoid using Seachem Excel, but the results were not good. Plus I had a precipitation on the bottle, maybe related or not to it, but since there was no improvement, I gave up on doing so, as it did not really make sense.

As usual, try it. Maybe it works for you.



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[Daveslaney]

Thanks Ed.
Just when i thought i was getting my head round this lol.
I recently changed my dosing but when i dosed APFUK EI heres the macro mix
4 tsp potasium nitrate
1 tsp potasium phosphate
6 tsp Magnesium sulphate
Uses this recipe for around a year no issues. Only really changed because i ran low on powders.
Now i use Nuno Ms EI recipe as i his journal Crystal Mountain. But still use MGSo4 in the mix with the micros.
As well as raising the GH i was also under the impression MG aids photosynthesis and acts as a catalyst for phosphate absorption in plants.
As my tap water is according to my tap water report 14dGh should i maybe drop the mg from my dosing?
Do a search on here for a thread ABOUT MAGNESIUM that explains it better than i ever could.

 

[Ed.Junior]

With 14 dGH you are "probably" covered on both Ca and Mg. I would try to get a water report and check. Maybe the ratio is much more on the Ca side, which is to be expected. 30ppm of Ca and 10ppm of Mg are reasonable amounts. You have much more than that, but knowing the ratio would be nice, to check if you can skip one or both.

Mg is very important, no questions about it. My suggestion is more about the dosing method, dosing Epsom salts after the change instead of dosing daily. If anything, it might be simpler to some people, which I understand



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[dw1305]

Hi all,

As my tap water is according to my tap water report 14dGh should i maybe drop the mg from my dosing?

I would try to get a water report and check.

It is quite difficult to find magnesium values for UK tap water, it isn't a parameter that water companies have to <"include in their report">. Like both potassium (K) and phosphorus (P) it is a "Non Regulatory Parameter" and doesn't have a "prescribed concentration or value" (PCV) under the <"water supply legislation">.

It is easy to test for if you have access to an <"Atomic Absorption Spectrophotometer"> you can get magnesium levels straight from a water sample without needing any reagents etc.

Most hardUK tap water doesn't contain much magnesium for geological reasons. A lot of our aquifers are limestones (Chalk, Oolite etc) that were laid down in ocean basins and are relatively low in magnesium. There is a more complete explanation in <"Too much light...."> as to why water elsewhere may contain more magnesium.

cheers Darrel

 

[Ed.Junior]

One could expect something like that, thats a shame. Our reports here in Germany are much different, very through, at least in Hamburg.

I would suggest adding Mg only (instead of Ca and Mg), wait some weeks, and then add nothing. Keep other variables untouched. Observe the plants and try to go for conclusions.

Please also consider seasonality in your water supply. No idea what goes on over there.

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[Daveslaney]

Thanks for the info.
For the cost of the salts and the target mg in my dosing is only 10 ppm, I think i will keep dosing the mg in the EI mix.
As most gh boosters from what i can gather are 4 parts ca to 1 part mg, i think the 10ppm mg alone will prob not make a big raise to my GH anyways?
But MG is still covered in my dosing routine.