Water soluble micros needs low pH?

[defdac]

I've come across a Swedish reference on the subject of how one should mix water soluble micronutrients (like CSM+B). It says the chelates are rendered useless if one try to mix micro-powders with ordinary tapwater. The chelates breaks down before they come in contact with the metal-ions if the water pH is above 4-5.

I use a micronutrient-powder called "NutriSi" (almost exactly like CSM+B) that has 50% EDTA and 50% DTPA iron. I get iron-deficiency-symptoms even if I dose the equivalent of 1 ppm Fe (10 times the recommended 0,1 ppm) several times a week. I roll it with tapwater (pH 8, KH 2, GH 3, Ca 22 ppm, Mg 2 ppm), but after this I think I will try to get some citric acid to lower the tap to pH 4 before I mix it with the powder.

Would it suffice to use distilled water or do one need to use some kind of acid also?

I will cross-post this message at the APD also.

 

[Ian H]

Re: Water soluble micros needs low pH?

There is always a danger in that we assume that anything written is fact.

It strikes me that if this assumption is correct, what happens if you add the trace solution to your tank after the acidification? On the assumption that you run your tank above ph 5 would this not nullify the acidification?

I will continue to make my traces stock solution with plain water as it works for me without complications.

Ian

 

[defdac]

Re: Water soluble micros needs low pH?

It strikes me that if this assumption is correct, what happens if you add the trace solution to your tank after the acidification? On the assumption that you run your tank above ph 5 would this not nullify the acidification?

I knew that question would be brought up, but it seems the actual chelate need to bind in an acidic environment (ph 4-5) to the metals in the powder. When they are bound they can stand the pH:s of our aquariums, especially the DTPA-chelate.

 

[Ian H]

Re: Water soluble micros needs low pH?

This is an extract from a web site related to chelates. (http://foliarfert.com/pages/chelates.htm)

What is a chelate?
Chelates are organic molecules that can trap or encapsulate certain highly reactive trace metal cations which prevents them from entering into unwanted chemical reactions and forming insoluble compounds, which are unavailable.

Chelates incorporate metal ions into a soluble but bound form, to make them available to the plant because they are very soluble in water.

Chelation is bonding the metal ion to an organic molecule, making the metal ion highly soluble.

A chelated form of a mineral has different qualities from the mineral itself.
One quality that can change is bioavailability; the ability to absorb and use the mineral.

May or may not be of use in reaching a conclusion.

Ian

 

[defdac]

Re: Water soluble micros needs low pH?

Exactly, the chelate will not "trap" certain highly reactive trace metal cations if the pH of the solution-water is above 4-5.

When the chelate has trapped the highly reactive trace metal cations the actual solution will have become, for example, DTPA/EDTA-chelated iron - which is less prone to oxidizing and is usable in a wider range of pH:s.

I've already made a new batch with 300 ml battery water and 1.5 tsp Citric acid (which rendered the water a pH of about 4.5) and then I mixed in the NutriSi-powder. The result is already obvious in that the old tapwater-based solution is blood-red and the new one is brown.

So it certanly is a big difference, and I will see if some of my pale new shoots will retain a more lush green color with the new solution.

 

[Tom Barr]

Re: Water soluble micros needs low pH?

Exactly, the chelate will not "trap" certain highly reactive trace metal cations if the pH of the solution-water is above 4-5.

When the chelate has trapped the highly reactive trace metal cations the actual solution will have become, for example, DTPA/EDTA-chelated iron - which is less prone to oxidizing and is usable in a wider range of pH:s.

Then the root comes along and does what to remove the Trace metal?
Acidifies the sourrounding area by adding H+'s. This frees the Fe from the DTPA.

So it certanly is a big difference, and I will see if some of my pale new shoots will retain a more lush green color with the new solution.

Folks' used HCL in the past(see APD) for CMS and to reduce preciptates under concentrated conditions.

Tank's are not concentrated and we do not not HCL to them either for long term storage of trace either.

Regards,
Tom Barr

 

[defdac]

Re: Water soluble micros needs low pH?

At least EDTA is used to measure Ca+Mg so if you have the EDTA-powder and mix it with ordinary tap-water it will react with the Ca+Mg right?