Simple PPM question

email468

Well-Known Member
Isn't RO water usually at a decent ph by itself?? Certainly less than 9! But, no I did not know that about the RO water...so thanks again, my friend.
All I know is when I tried to pH check RO water my meter would not settle on a pH it jumped up and down.
 

Earl

Well-Known Member
Just a tip.

Avoid putting your pH probe in RO or Distilled water.

It really messes up the probe.


Only use tapwater and a soft toothbrush, to clean the probe.

Re-Calibrate your meter if you tap it on the rez.

Calibrate at both 4 & 7
at least once a month.


Your pH meter is a precision instrument that is relatively fragile,
and needs some care.

The better you treat your pH probe,
the longer it should give you trouble free use.

If you look at the probe tip,
you will see a glass ball,
full or partially filled,
with a liquid.

This is a solution,
that compares its contents,
to your nutrient solution,
and converts the difference into a meter reading.

It is actually reading the H+ (hydrogen) ions in solution,
which is a measure of the acidity.

By comparing the measured H+ concentration,
with a reference or stable value,
the meter then is able to display a pH reading on the meter.


Why is it important to keep the pH meter tip wet?
pH meters use a cloth junction in the construction of the probe.
If this dries out, the meter will not be able to read a correct value.

Why is my pH meter tip covered with salt deposits?
This is normal when the probe is new
because the storage solution has dried.
Any occasional salt residue
should be rinsed off with a soft toothbrush and tapwater.

How do I use my pH meter?
Gently shake the tip downward to displace any air bubbles.
Immerse in pH 7 reference solution to calibrate your meter.
Dip the probe in a cup of tapwater,
and then immerse in pH 4 reference solution,
and calibrate the meter.
Check 7 and 4 until the meter reads correctly in each fluid.
When calibrated, re-rinse and immerse in your reservoir solution.
Keep the probe in the nutrient solution, if at all possible.
Moving the probe is the most likely cause of it to lose calibration.

If you have other probes in your rez,
make sure they are at least three inches apart.


How do I store my pH probe?
To store, rinse in tapwater.
Place a small amount of storage solution in the cap, and close.
DO NOT STORE THE pH PROBE IN DISTILLED WATER!

How long will my pH probe last?
If you take excellent care of your meter
the probe should last for 18 to 24 months.

How can I tell when my pH probe is 'fading'?
If your meter doesn't give consistent and repeatable readings
with reference solution,
then you should replace the probe.
A simple test is to place the probe in soda to read a pH of 2.7 to 3.9,
and then quickly place in Windex with ammonia.
If the display quickly changes from the lower value up to pH 10 to 11,
then the probe is fine.
If it moves slowly upward, it might be time to replace it.

Can I reuse my calibration solution?
NO! Any contamination can quickly change the solution.

How often do I calibrate my meter?
Get to know your meter.
A good meter will hold its calibration.
If you test it and it is always calibrated correctly,
then you can safely extend the time between calibrations.
Moving the probe can cause it to lose calibration.

All these instructions,
are for meters designed to be left in the solution full time.


.
 

email468

Well-Known Member
Earl - since you are here - do you know why RO water is bad for pH meters? and why it can't seem to be pH'ed (other than it destroys your meter)?
 

Earl

Well-Known Member
A pH probe is basically a sensitive voltmeter,
and converts the reading in mV that it gets,
into a digital number representing the pH.

A solution of neutral pH should have a mV reading of 0.0.

Two chemical solutions can have the same pH,
with one solution having a higher ionic value.

pH calibration solutions are made with High Ionic chemicals.

High Ionic solutions will cause the meter to react faster,
than low ionic solutions.

RO has little or no ions.

Two potentials are needed to make a pH measurement:

1. The sensing electrode provides a potential
proportional to the logarithm of the
hydrogen ion activity,
in your nutrient solution.

2. The electrode reference solution inside the probe,
ideally provides a stable and consistent ionic potential,
independent of your nutrient solution.

Comparing the ions in these two solutions
gives an electrical potential
we can read on the meter.

Since the RO has no ions,
ion transfer occurs
from the electrode reference solution in the probe,
to the RO.

Once the ions are reduced in the electrode reference solution,
or depleted from the electrode reference solution,
the probe becomes slow to calibrate, or totally disabled.

Ph adjusting RO has the same ionic problem.

.
 

email468

Well-Known Member
A pH probe is basically a sensitive voltmeter,
and converts the reading in mV that it gets,
into a digital number representing the pH.

A solution of neutral pH should have a mV reading of 0.0.

Two chemical solutions can have the same pH,
with one solution having a higher ionic value.

pH calibration solutions are made with High Ionic chemicals.

High Ionic solutions will cause the meter to react faster,
than low ionic solutions.

RO has little or no ions.

Two potentials are needed to make a pH measurement:

1. The sensing electrode provides a potential
proportional to the logarithm of the
hydrogen ion activity,
in your nutrient solution.

2. The electrode reference solution inside the probe,
ideally provides a stable and consistent ionic potential,
independent of your nutrient solution.

Comparing the ions in these two solutions
gives an electrical potential
we can read on the meter.

Since the RO has no ions,
ion transfer occurs
from the electrode reference solution in the probe,
to the RO.

Once the ions are reduced in the electrode reference solution,
or depleted from the electrode reference solution,
the probe becomes slow to calibrate, or totally disabled.

Ph adjusting RO has the same ionic problem.

.
Thank you, Earl!
 

420inmyapt

Well-Known Member
Sorry to rehash a month old thread, but is there any kind of PH test you can preform on RO water that will give you an accurate result? R/O DI water to be specific. Do i have to use the test strips? cause i am all but sure this is way my PH meter doesn't work....blah blah blah nothing like breaking your $100 toy....
 

email468

Well-Known Member
Sorry to rehash a month old thread, but is there any kind of PH test you can preform on RO water that will give you an accurate result? R/O DI water to be specific. Do i have to use the test strips? cause i am all but sure this is just my PH meter doesn't work....blah blah blah nothing like breaking your $100 toy....
It is my understanding that you only want to adjust pH after adding nutrients anyway so no worries.
 

420inmyapt

Well-Known Member
So if i adjust/test after adding nutes, have the nutes added ions so my PH pen wont be depleted? So Basically just stop testing my water and only test my res.......
 

email468

Well-Known Member
Thank you buddy, hopefully i haven't completely ruined my PH pen :) +Rep for you
From what i understand, the risk is minimal as it takes some time to occur. I think the real danger would be from a continuous probe - rather than a hand-held.
 

jonask

Well-Known Member
sorry to dig up this subject again...

but if i want to do the final flush on the plants using RO water would I check the PH , or better, how do i stabilize it for a constant 6,3Ph ... or on the final flush it doesn't matter if the ph is high or low!
 
Top