# pH adjusted flush water



## MickFoster (Jul 28, 2009)

I understand that the pH has to be in a certain range for the plant to uptake nutrients effeciently. Can somebody please expain why plain water for flushing has to be pH adjusted? Does the plant need pH adjusted water to just drink?

Thanks!


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## MickFoster (Jul 29, 2009)

Wow! 33 views and everytime I look there are at least 90 people viewing the hydro section - nobody has an answer? Everybody always insists that you flush with pH adjusted water but nobody knows why?


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## GoldenGanja13 (Jul 29, 2009)

YES,The plants need the ph to be set for dring water alone. The water sets in the soil. So if you have soil and your ph is 6.5 all the time then you toss in a gallon of 7.0 well that will throw the roots off and also change ph in soil.


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## MickFoster (Jul 29, 2009)

GoldenGanja13 said:


> YES,The plants need the ph to be set for dring water alone. The water sets in the soil. So if you have soil and your ph is 6.5 all the time then you toss in a gallon of 7.0 well that will throw the roots off and also change ph in soil.


I appreciate the input - I should have told you that I grow Hempy - no soil.


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## GoldenGanja13 (Jul 29, 2009)

MickFoster said:


> I appreciate the input - I should have told you that I grow Hempy - no soil.


 None the less, when you fluxuate your Ph, it really screws with the root system.


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## Earl (Jul 29, 2009)

Here is a picture of my hempy bucket grow.
I flushed with RO only(No pH adjustment)





Before flushing


After RO only flush












There is no reason to pH adjust the flush.

If you are using RO or distilled water,
you should not try to test the pH,
as this will degrade the probe.


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## jberry (Jul 29, 2009)

Earl said:


> Here is a picture of my hempy bucket grow.
> I flushed with RO only(No pH adjustment)
> 
> 
> ...


why will it degrade the probe if you test ro water? i never knew that!

and about not adjusting the ph 4 flushing... does your ro water come out close to your desired range? maybe thats why YOU dont bother adjusting? or is it off by a lot? - (i know you just said not to test ro water but im assuming youve tested it at least once)


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## jberry (Jul 29, 2009)

nevermind earl, i took a quick look at your journal and you have all the info there.

new question: if you do put your meter in ro water than is there any way to repair the probe? like recallabrating it?

ive put mine in r/o water a bunch of times and its still on point... (i check it about once a week) but i'll take ur advice anyhow.

i also have adjusted my r/o water with ph down for all my flushes (without problem) but i wont next time cuz what you say makes since.
i did note that plain r/o water needed very little ph down!! 1ml would drop the ph as much as 30ml normally would !


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## Earl (Jul 29, 2009)

In theory RO is 7.0
This is very hard to measure 
since there are no free ions in pure H2o

We are measuring the potential of Hydrogen(pH) ions
that are free in the solution.

Pure H2o has no free ions 
since they are all bound up with the oxygen ions 

Your probe contains a either a silver cathode reference wire element,
or silver ion electrolyte reference fluid.

In iether case, your probe will give up ions 
to the ion free RO water.

Giving up these reference ions 
will slow the response time of your meter
and make your calibrations inaccurate.

It is just good practice 
to avoid letting your probe come into contact 
with low ion fluids such as RO or distilled water.

Always keep your probe wet with saltwater 
or nutrient solution,
or pH 4 calibration fluid.

You can make you own storage fluid with table salt and RO
Just check it often to make sure it does not dry out.


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## QuentinQuark (Aug 6, 2009)

I am doing my first flush, and didn't adjust the ph.

I theorized that the nutrient that would get dumped back into the res would drop the ph substantially, and I was bang on.

I drained the res and filled with filtered water (Mr. Clean Autodry). 48 hours later the ph was 5.4! So I drained and filled again, this time with tap water, because the Autodry takes way too damn long. I will see what the ph is in a day or two, if it has dropped again substantially then I will drain and fill again with plain water. If it hasn't dropped, then I will drop it down and see what happens, I am going to try and suck every last drop of nutes outta the plants cause last time the tasting fricking terrible.


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## Earl (Aug 6, 2009)

What brand of nutes are you using ?
What was the max tds you used during flower ?


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## proheto8008 (Aug 6, 2009)

Earl said:


> In theory RO is 7.0
> This is very hard to measure
> since there are no free ions in pure H2o
> 
> ...


thank you man... i just made a thread looking for exactly this info. I just got a ph pen and i wanted to know if there was a diy method to store it.


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## diowk (Jun 2, 2010)

RO water is always around 4.0-4.5 for me... why? Is it honestly off by 2.5-3 full points? If so, then why bother with monitoring ph using RO water at all?


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## toostonedto (Apr 7, 2011)

I have a RO unit, and the EC of it is 30sm(15-21ppm). I DON'T believe RO water is bad for your probe to test, because most RO units will have as least a little of something in it, giving enough ions to at least test. Still not a good idea to store the probe in RO water, but testing it should be fine. Unless your RO unit can not only remove particulates, but also ions, which I don't think is possible.

Deionized or distilled water literally has no ions in it, so it would be bad for your probe.

I'm not an expert though, but I did stay at a Holiday Inn!!


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## Silky Shagsalot (Apr 8, 2011)

Earl said:


> Here is a picture of my hempy bucket grow.
> I flushed with RO only(No pH adjustment)
> There is no reason to pH adjust the flush.
> If you are using RO or distilled water,
> ...


totally correct! do not adjust the ph to your medium when flushing. in fact, adjust the ph to be out of whack with your medium. you don't want your plants taking in nutes while flushing. you want them to take in plain water in order to enable the plants to expel the stored nutes in the leaves etc. as for the degrading the probe, i use r/o water and my probe is fine....


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