Roots and calcium

[Roberta]

I think that you are correct... you do the best that you can do - we all make compromises. In a few months, you will get rain, which will help the situation a lot.

[Kollba]

Maybe someone is interested in an update:

Yesterday I got a pH meter (not the cheapest one) and today I calibrated it with the attached "calibration powder" dissolved in distilled water.
I got very surprised when I noticed that the distilled water had a pH of 5.8, because I was convinced that it should be very close to 7, so I started to doubt the meter. Then I found a couple of webpages saying that distilled water very fast absorb carbon dioxide from the air and stabilize at a pH around 5.8.
So... My water has pH 6.8, EC 1270 and TDS 636.
The EC/TDS shows that I have more dissolved minerals in my water than I want, and the pH could be a little bit lower.
I tested water + vinegar and found that 10 ml per liter water gives a pH of 5.1 which I have started to use on a few leaves and 2 orchid roots.
I will be back in some weeks (months ?) with the result of this test.

[camille1585]

Originally Posted by Kollba

Maybe someone is interested in an update:

Yesterday I got a pH meter (not the cheapest one) and today I calibrated it with the attached "calibration powder" dissolved in distilled water.
I got very surprised when I noticed that the distilled water had a pH of 5.8, because I was convinced that it should be very close to 7, so I started to doubt the meter. Then I found a couple of webpages saying that distilled water very fast absorb carbon dioxide from the air and stabilize at a pH around 5.8.
So... My water has pH 6.8, EC 1270 and TDS 636.
The EC/TDS shows that I have more dissolved minerals in my water than I want, and the pH could be a little bit lower.
I tested water + vinegar and found that 10 ml per liter water gives a pH of 5.1 which I have started to use on a few leaves and 2 orchid roots.
I will be back in some weeks (months ?) with the result of this test.

I'm not sure I quite follow.... You tested the pH of distilled water, with came out to 5.8. What does the second measurement (pH 6.8, EC 1270 and TDS 636) correspond to then? If this is distilled water+fertilizer, you can reduce the EC and TDS by using less fertilizer.

A pH of 5,1 is rather low and 5,8 (or 6,8 if that isn't a typo) would be preferable. Honestly, unless your pH is really too high or too low it's perfectly acceptable to use the water as it is.

[Ray]

I agree with Camille, but will add that you should not trust that TDS reading.

If we assume your distilled water is essentially mineral-free, then all of the EC is coming from the fertilizer.

I don’t know the formula you’re using, but at 100 ppm N - a reasonable level for weekly feeding - MSU RO (Rain Mix is a European knock off) will have an EC contribution of 800 microSiemens/cm and a true TDS of 740 ppm.

[Dusty Ol' Man]

I believe he said the distilled water test was used only to calibrate the meter. The other numbers are for his tap water.

[Kollba]

Originally Posted by camille1585

I'm not sure I quite follow.... You tested the pH of distilled water, with came out to 5.8. What does the second measurement (pH 6.8, EC 1270 and TDS 636) correspond to then?

A pH of 5,1 is rather low and 5,8 (or 6,8 if that isn't a typo) would be preferable. Honestly, unless your pH is really too high or too low it's perfectly acceptable to use the water as it is.

It is implied from previous posts that "my water" is the water from my well that I am using for my orchids and have problems with.

Using a lower pH (water + vinegar) is a test to see if it can remove (or reduce) the coating of lime on the orchid roots.

---------- Post added at 10:11 PM ---------- Previous post was at 10:08 PM ----------

Originally Posted by Dusty Ol' Man

I believe he said the distilled water test was used only to calibrate the meter. The other numbers are for his tap water.

Correct.
Maybe I was a bit unclear there...

It was just a curiosity because I always thought that distilled water kept PH 7.

[Ray]

Originally Posted by Kollba

It was just a curiosity because I always thought that distilled water kept PH 7.

You're earlier comment about the absorption of carbon dioxide is right on. At the 400 ppm average CO2 content of the air these days, the equilibrium pH is in the 5.7-5.8 range, but the carbonic acid that is formed is such a weak acid that pretty much anything else that is added to the water completely overwhelms it.