which ph test to trust?

[Dr.GreenThumb]

my water is about 7 or so from the tap.. I have a well. Same everyday for years. I'll know exactly once my new ph pen gets here.

I agree that it may be possible for some growers depending on how/where you get your water that the PH is "close enuf." I tried a experiment today, my tap water was a ph of 8.2. I went to the local grocery store and purchased a gallon of "pure spring" water......ph was 7.6. On the way back home stoped at one of thoes "pull up" stations where you can get water.....ph was 8.0. To bad the city wont let me put a well next to my apartment to fix my water issues...

 

[KADE]

Well wells can create all sorts of other problems... like too high ppm. I forget what mine is, I can probably find the paper tomorrow... My area was flooded not too long ago.. we were forced to move (even tho i live over 50ft above the water level). Anyways, in order to be able to go back in the place we had to get the water tested... I'm under 50 ppm... which is exceptional... my neighbours are up higher.. and many can't use the water because it has too much iron... hard to believe drilling 50 feet further left or right has such a huge impact.

 

[ROOR]

I hear theres no flouride in well water!?!?

 

[KADE]

that is correct,....well unless u live in an area with it in the soil... not any in my area... no bromine or chlorine or ne of that either... so when i wanna water i pour it into my rez... and put in 18 drops of ph down.. n away i go =0

 

[Mummyscurse]

We don't have the hardest water, in our community (filtered, Lake Huron water), but I took the added step of purchasing an inline water filter, that I'll hook up to a garden hose outlet, from which I'll fill my watering containers. Just wondering if there are likely to be any important trace minerals I might be filtering, such that filtering the native water may do more harm than good?

Is filtered water or distilled water always a "good thing"? Intuitively, it seems to me that you will reduce the water chemistry variables you otherwise have to deal with, if you're able to use distilled or filtered water, before adding your own nutes.

In line with this thread, is it likely that filtering will reduce the PH, as a rule of thumb?

 

[AeroTX]

hmmm maybe that is why I am getting yellow leaves. I am at the flushing state before I harvest so the only nutes I was using was some hormone and to keep the ph in balance.

 

[Mummyscurse]

And....with a bit more Google searching, and to muddy the "waters" further, I found this interesting bit of text at: http://www.lenntech.com/deionised-demineralised-water.htm

====================================================
Pure water by definition is slightly acidic and distilled water will test out around pH 5.8. The reason is that distilled water dissolves carbon dioxide from the air. It dissolves carbon dioxide until it is in dynamic equilibrium with the atmosphere. That means that the amount being dissolved balances the amount coming out of solution. The total amount in the water is determined by the concentration in the atmosphere. The dissolved carbon dioxide reacts with the water and finally forms carbonic acid.

2 H2O + CO2 --> H2O + H2CO3 (carbonic acid) --> (H30+) (charged acidified water) + (HCO3-) (charged bicarbonate ion)

Recently produced distilled water has a pH-value of approximately 7, but affected by the presence of carbon dioxide it will reach a slightly acidic pH-value within a couple of hours. Additionally, it is important to mention that the pH of ultra-pure water is difficult to measure. Not only does high-purity water rapidly pick up contaminants - such as carbon dioxide (CO2) - that affect its pH, but it also has a low conductivity that can affect the accuracy of pH meters. For instance, absorption of just a few ppm of CO2 can cause the pH of ultra-pure water to drop to 4.5, although the water is still of essentially high quality.

The most accurate estimation of the pH of ultra-pure water is obtained by measuring its resistance; for a given resistance, the pH must lie between certain limits. For example, if the resistance is 10.0 MWcm, the pH must lie between 6.6 and 7.6. The relationship between the resistance and pH of high-purity water is shown in the figure below.
==================================================

Now, what I find interesting, and a bit alarming about these comments is the increased absorbsion of carbon dioxide by "high purity water". Correct me if I'm wrong, but whereas increasing the level of carbon dioxide in the air is a good thing, increasing carbon dioxide levels in water is a TERRIBLE thing! I never was aware that pure water absorbs (if "absorbs" is the right expression for the process) carbon dioxide at much higher rates. And, how many of you were aware that low conductivity in the water you're testing, will dramatically effect the PH readings? Very interesting stuff...

 

[ROOR]

distilled water has no trace elements in whatsoever....rainwater is a good source of nitrogen....

 

[justawannabe]

good debate going on in this thread. Being a dirt farmer for a few years now, I've never been a huge advocate of PHing my nutrient water before adding to the soil. I have tried it with limited to negative results (dropped it to low).

A good commercial potting soil, or even an organic gardeners own personal mix, will PH out between 6.5 and 7.
If you are concerned, lime can solve the problem. Most nutrient salts drive the PH of the water down, and lime in your soil is a safe way to bring it back up without risk.

 

[ROOR]

Id rather know then not....just my two cents!

 

[Dr.GreenThumb]

In line with this thread, is it likely that filtering will reduce the PH, as a rule of thumb?

With no documentation to back up my statement, I will say NO that a filter will not change the Ph level of H2O. But then again a filter removes minerals, chemicals, ect and do thoes not help makeup the Ph level of the water you are using??? Make any sense?

 

[Dr.GreenThumb]

Id rather know then not....just my two cents!

Maybee all it helps is our stress level....lol

 

[Canso]

With no documentation to back up my statement, I will say NO that a filter will not change the Ph level of H2O. But then again a filter removes minerals, chemicals, ect and do thoes not help makeup the Ph level of the water you are using??? Make any sense?

My tap water is 170ppm and Ph 8.5
I use Reverse Osmosis water and the PH comes out at 4.5-5.
Because it has nothing to buffer Ph, 1 drop of ph up will increase 20gal. to Ph7

 

[astra007]

if 1 drop of ph up will change 20 gal that much yer ph tester is totally screwed. i use a 14 gal. res and i use 50ml to bring it down after using GH 3 part which are ph buffered.

 

[astra007]

i use 2 hanna pens to double check my ph. you ever had nutrient lockout? this is caused by yer ph being out of whack - to high or to low. i also use GH 3 part chem that has ph down already in it. dutch master dont have this. fill yer res. then add yer ferts AND then adjust your ph level.

i get people in town givin me crap all the time for using ph down. stupid fools dont understand that im not on city water which is 6.0 for them.

 

[Canso]

the water out of the Reverse Osmosis filter changes very easly, after nutes is a diferent story.
but like i said before I fill my res. with 20gal. RO water, I add nutes, and water my plants. my ph is fine, no PH adjustment nesesary. I only check PPM's.

 

[astra007]

when i feed - using 3 part GH - i do not have to ph much but when its water only then its 100ml. ph down to 6.2 in 14 gal. fer me.

 

[KADE]

I have to add 6 drops PER LITRE to drop one point. My ppm is way low... 50 or so... I agree with astra.

 

[Canso]

I have 5 ppm in the reverse osmosis water, it is extremely pure. I bought Ph up and down Advanced Nutrients pure concentrate over 2 years ago and they are still over ¾ full. I think you guy’s are using something different (cheap junk) if your putting that much in. 100ml is crazy

 

[astra007]

not when ya start with 8.0 ph water. and you are dropping to 6.2 max gonna check it out thxs