I posted this on TPT but it's stuck in a moderators inbox, probably until someone rolls the server out of the ditch it's currently in.
Thought I would document the process of building a new mixture for reference purposes.
500ml Micro Mix @ 1ml/10L -
Fe 0.15
Mn 0.05
Zn 0.04
B 0.03
Cu 0.002
Mo 0.0015
Ni 0.0005
This mix includes a liquid Fe Gluconate component, 'Grow Microbe-Lift Plants Fe' (bottle instructions 1ml/100L - 0.1 mg/L and the solution in the bottle is pH 3.05).
The preparation water is RO/DI (Tap TDS 35, post treat TDS <1ppm, it really should be 0ppm but I think my DI resin is exhausted as the gauge flickers between 0 and 1 ppm when drawing water (TMC RO/DI unit).
I acidified the water beforehand using Ascorbic acid (I had this already and should have used it with the previous 5L preparation noted in my last post) and checked the pH of the solution before adding the salts. At the addition of each salt there was vigorous mixing to achieve near full dissolution (salt crystals disappearing on visual inspection after each shake of the bottle) then the pH probe was put in the resultant mixture and the reading was allowed to stabilise for 5 mins before it was noted down. The following list shows the respective weights of the salts addition and the resultant pH of the mixture, the Mo, Cu and Ni component is derived from individual pre prepared solutions (100ml containers dosing at 10ml/5L for Mo 0.0015, Cu 0.002, Ni 0.0005).
500ml Micro dosed @ 1ml/10L, Preparation as follows -
450ml RO/DI + 0.25g Ascorbic Acid - pH 3.2
+ 0.77g MnSO4.H2O (Mn 0.05 mg/L) - pH 3.42
+ 0.9g ZnSO4.7H2O (Zn 0.04 mg/L) - pH 3.5
+ 0.86g H3BO3 (B 0.03 mg/L) - pH 3.5
+ 0.019g Na2MoO4.2H2O (Mo 0.0015 mg/L) - pH 3.6
+ 0.04g CuSO4.5H2O (Cu 0.002 mg/L) - pH 3.68
+ 0.0113g NiSO4.6H2O (Ni 0.0005 mg/L) - pH 3.74
At this point the resulting mixture is clear with zero precipitation. The addition of the Fe increases the opacity of the mixture.
+ 50ml Fe Gluconate (pH 3.05 - Fe 0.1 mg/L) - pH 3.35 (Green tint to the mix)
+ 2.275g FeDTPA 11% (Fe 0.05mg/L) - pH 3.19 (Brown Green tint to the mix)
The mixture was allowed to stabilise overnight and on visual inspection the next day there was no sedimented precipitation detected, however there is a wispy milkiness on the interior surface wall of the bottle that dissipates fully when the bottle is shaken, I have seen this before with the FeDTPA at this same concentration when added to a mixture of Flourish Trace and Flourish Comprehensive (50ml Trace, 6ml Comp, 4ml RO/D1, this mixture gives Mn 0.02, B 0.007, Zn 0.04 and 0.1 Fe when dosed at 3ml/10L, the addition of 0.09g FeDTPA 11% and 0.02g MnSO4.H2O fortified it to Mn 0.05 and Fe 0.15 @ 3ml/10L (considering FTrace should be dosed @ 0.625ml/L that got expensive fast). This mixture still worked really well although the FeDTPA is slightly out of its range in the bottle and should be nearer pH4. With this in mind the next new mix I make I will target pH4 for the resultant solution and record what happens to the ingredients when mixed together at this pH.
It's now in the dosing pump bottle, first full dose should reach the tank day after tomorrow (when line from dosing pump to tank clears of previous mix), will be interesting to see what my Buce think of the extra B, Ni, Mo, 4x reduction in Cu and zero Cobalt.
I have a couple of questions.
Is it worth adding any Cobalt? I have the chloride to hand and could add it to the mix at a very low concentration if need be. (Trace and Comprehensive both have it listed).
Also has anyone put any thought to why Seachem are adding into Flourish Trace Vanadium Sulfate and Rubidium Chloride (even stating on the label 'NON-PLANT FOOD'), is it a ubiquitous contaminant in one of their base ingredients? or is it added to differentiate their mix from other similar products? As a point of note they are not listed as ingredients in Flourish Comprehensive and neither is Nickel. I am wondering if they are being added intentionally due to the higher concentration of Zinc and additional use of Nickel in the Flourish Trace, maybe to somehow keep the resultant mixture stabilised and available in the bottle for longer shelf life (not looked it up so pure speculation), hopefully it's not akin to adding Gold Leaf flakes to Vodka to make it more 'Special'.