What does your RO water ph at?

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MendoAdome

MendoAdome

SUPER informative guys!!! I've been having a pH issue I'm hopeful you scholars can help me solve! I have the Blue Labs pH pen.

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http://www.amazon.com/Bluelab-pH-Pen-Plant-Germination/dp/B005POOJHG

When I bought it, I got two so I'd have a back-up. I've been using only one of them for about 9 months now. I've been having pH problems which have worsened over the last 2 months or so. The problems are most apparent in early veg. The plants become stunted and get what I had thought was burn (but no feedings have been given at all, and I'm using straight Happy Frog soil -- shouldn't burn). Here's an example of what I'm seeing...

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I cleaned my probe with the Bluelabs probe cleaner and recalibrated. Then I put the meter in the 7.0 solution, it goes right to the "7" number. When I rinse and put it in the 4.0 solution, it goes right to 4.0! I calibrate and get a check mark indicating a successful calibration.

SO...I hydrated and calibrated my back-up unit thinking it was time to put it into service. Well..it seemed to take a long time for the meter to get to the 7.0 number. Then, after rinsing and placing into the 4.0 solution, the meter never did get all the way to 4.0. It only got to around 4.5-ish, and it took forever for it to get there! I hit "CAL" and again got a check mark indicating a successful calibration.

My problem is that the two meters now read differently and I'm not sure which to trust! The "old" meter still settles in on a number pretty fast, while the newer back-up meter is still taking a long, long time to get settled on a number. In fact, the auto shut off hits several times usually before it's done. The readings are several points apart with the newer back-up meter reading a higher pH in any solution. Example: When the old meter is reading 6.5, the newer back-up meter will be reading 6.7-9.

Common sense is telling me since I've been having unexplained pH problems (I've been suspecting my soil up til now) I should start using the newer back-up meter which is reading higher. However...something in my gut is telling me not too. It may just be my lack of confidence due to it's slow reading and difficulty calibrating.

I would really appreciate some of you all-knowing pH gurus lending me your advice! Would you trust the new meter or stay with the old? Do my problems in the pics look like they might be caused by higher pH or a lower pH? This would help me in deciding too.

Thanks so much in advance!

Best,

Max

Its not a burn but rather a deficiency. If it was a toxicity you would see burnt leaf tips.

Ca will have the brown spots intervienly not JUST on the perimeter.

Keep in mind every time you put that probe into your nutes some of those nutes will transfer up into the reference solution, if you ever have seen the clear probes you can see this happening.

I would not worry quite yet. 0.2 is not a big difference considering that you have been using it longer I would not worry about it. MAKE sure you calibrate your probe and make sure to check it before everytime you use. it. Basicly you need to calibrate it every 30 uses. so you check your water 10 times a day then every three days you need to calibrate.
 
G

guyindc

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Sorry, I know this is an old post. But I am also wondering, how would you measure the pH of RO water if it will mess up the chemistry of the pH pen? I have a question in with Blue Lab (my pH pen manufacturer), how would I do it then......... no reply yet.
 
Seamaiden

Seamaiden

Living dead girl
Distilled water (the only truly pure form of water, to the best of my knowledge) is what screws up meters, but in any event you can use strips or colorimetric titrated drops.
 
G

guyindc

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By the way, do you guys like using the litmus paper type pH test strips where you just dip it into the water, or do you like the pH test drops like the one by GH?
 
MendoAdome

MendoAdome

Water will only screw up the probes if you use it as storage and in actuality every time you take a measurement your putting some water into the probe via osmosis. So seamadien your not quite correct. Make sure you store the probe in kcl probe solution and your probe will last a few years
 
MendoAdome

MendoAdome

The drops become increasingly inaccurate with nutrients in the water. Which would be detrimental to viceroys plant health
 
G

guyindc

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Water will only screw up the probes if you use it as storage and in actuality every time you take a measurement your putting some water into the probe via osmosis. So seamadien your not quite correct. Make sure you store the probe in kcl probe solution and your probe will last a few years
Hi MendoAdome, so are you saying that a quick measurement for a few minutes of the pH in RO or distilled water is ok, as long as right after that, I soak it back in KCl solution?
 
justiceman

justiceman

That's the thing with low to no EC water, it has zero alkalinity. What's alkalinity, you ask? It is resistance to pH shift. So what you're observing is water that has no resistance to pH shift and thus it will shift with changing CO2/O2 levels (CO2 drives pH down, O2 drives it up).

Bluelabs come highly recommended, assuming yours is properly calibrated, then that's what I think you're observing.

^^^^^^ In other words trying to read the Ph of R/O water is useless. I like to add .1-.3EC of my tap water back into my R/O before I take a Ph reading.
 
MendoAdome

MendoAdome

That's what almost probes are used for. Always store your probe in proper kcl solution otherwise your probe will go bad
 
MendoAdome

MendoAdome

Measuring the pH of Aro water or distilled water is not necessarily useless it's good to know as a basis point where you're starting from its also are you still featured to see what kind of life your filters having them as well because as the filters get older so will the pH it will raise
 
justiceman

justiceman

Measuring the pH of Aro water or distilled water is not necessarily useless it's good to know as a basis point where you're starting from its also are you still featured to see what kind of life your filters having them as well because as the filters get older so will the pH it will raise

That's the thing. It doesn't give you a point to show you where you are starting because the PH is so easily affected from the lack of alkalinity and it doesn't have to. It is the basis point literally. Technically pure water has a PH of 7 but if even a drop of a base or acid happens to be in the water the PH will be largely affected as compared to say .4EC tap water.

I'm not sure what you mean by testing your filters with a PH pen. i use an EC meter to see if the R/O membrane is still functioning correctly.
 
MendoAdome

MendoAdome

Ph does not adjust as easily in RO water because the salinity is nearly zero but you can still measure it adjusting it takes a lot of finesse
 
mojavegreen

mojavegreen

Water will only screw up the probes if you use it as storage and in actuality every time you take a measurement your putting some water into the probe via osmosis. So seamadien your not quite correct. Make sure you store the probe in kcl probe solution and your probe will last a few years
Store my blue lab probes in tap water with a dash of dish detergent. Last long time.
 
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