K-lite math check and precipitate issue

[smokinjoe1952]

I have adopted the K-lite 25 ppm N for every watering for about 6 months now. It seems to work well.

>First though, please check my math.

I make concentrate from 20 oz water and 1 oz K-lite.

I add 15ml of the concentrate to each gallon of r/o plant water. Is my math correct?

>Second - My concentrate keeps precipitating white particulate about 3-4 weeks after mixing it up. I kept it in the lower level of the house where it was around 68-72 24 hours a day, but 3 or 4 batches have precipitated white particles.

I researched the subject, and found that somebody had solved that problem by mixing the K-lite with boiling water, then keeping the concentrate refrigerated until you want to use. I just mixed some up today using that method, although I cut it down to 10 oz and water and .5 oz K-lite to make a smaller batch.

Does anybody know if there is a good chance of this new procedure solving the precipitate issue?

Thanks,

-Joe

[rbarata]

I haven't checked your calculations but I think your problem is related with temperature. Did you put the solution in a cooler place after done?
Solubility decreases with temps so if you have an almost saturated solution, when the temps go down it precipitates.

[smokinjoe1952]

In the past I have kept it ~68-72, but now it is in the refrigerator. I won't know for a month if that helps.

[Ray]

Your math is correct.

The problem is that calcium and magnesium ions are not particularly stable in solution, can combine and precipitate. If your water already contains those ions, it'll happen at lower concentrations.

The more dilute your concentrate, the less the tendency to precipitate. Why not put 0.4 ounces in a gallon, then use that a cup at a time to make up a gallon for application?

[rbarata]

The K-lite label recommends to dissolve 1 oz concentrate/128 oz water (1 gal).
What you've done was 20 oz water and 1 oz concentrate/0.1563 gal water (20 oz). So you should have used roughly 6x more water.
So I suspect your initial calculation might not be a good starting point.
I didn't understand what you have done after with the concentrate.

[smokinjoe1952]

I am using 11 ppm ro water to make the concentrate. (cheap tds meter)

It sounds like I need to make a more dilute concentrate if my current experiment fails.

Thanks for the help. I had not really thought of a more dilute concentrate solution for whatever reason!

Anxious to see if the refrigeration helps with my current concentration though.


Joe

[Ray]

Minerals have all sorts of different solubilities. Some improve with higher temperature, some improve with lower temps over a certain range.

I cannot say what is specifically happening, but my "gut feel" is that cooling is the wrong way to go.

[smokinjoe1952]

Just a follow-up. I used the boiling water method described above, then have kept the solution in the fridge since January, and there is no precipitate whatsoever. YMMV, but if you want to keep a fairly concentrated solution of K-lite, you might give this method a try.

Joe