Reverse Osmosis and Ph

[Bain]

So I'm pretty new to growing and I've been reading about ph levels. I've been watering with reverse osmosis water and assumed it was pretty close to 7.0 or lower. Today I got a water test kit and a soil ph meter. I tested the ph of my RO water and it ended up being around 7.5+.

Is that strange? I expected it to be lower. maybe 6.5-7 from what I've read.

Could this ph problem be the reason I've been having a few issues with germination?

Also, the cheap soil ph tester doesn't seem to work very well (I know, you get what you pay for). Does anyone have a soil ph tester that they can suggest that doesn't cost a ton? Something you know is accurate?

Thanks in advance for any help

 

[email468]

i think this thread may help...
https://www.rollitup.org/hydroponics-aeroponics/57961-simple-ppm-question.html

and Earl's all you ever wanted to know about pH and more...
CC Hydro 101 by Earl - Cannabis Culture Forums

 

[GrnMan]

Is that strange? I expected it to be lower. maybe 6.5-7 from what I've read.

Good RO water will be around 7.5. I use Fiji (only the best for my babies) and it states on the bottle that it has a ph of 7.5. I usually lower it a bit anyways, to around 6.5.

Could this ph problem be the reason I've been having a few issues with germination?

I've germinated my seeds in 7.0-8.00 water and they sprouted some tap roots.

Also, the cheap soil ph tester doesn't seem to work very well (I know, you get what you pay for). Does anyone have a soil ph tester that they can suggest that doesn't cost a ton? Something you know is accurate?

Yea dude, those shitty ass meters by rapid test suck donkey balls. Invest in a good digital meter! If you get your water ph to an acceptable level, your plants will love you - even if you don't feed them nutes!

 

[email468]

might want to read through those threads - you'll find that RO water destroys your pH meter and can't get an accurate reading until after adding nutes anyway.

 

[GrnMan]

Talkin to me email? LOL, damn I'm stoned...

and can't get an accurate reading until after adding nutes anyway.

Isn't that all that matters anyways - LOL?!

 

[email468]

Talkin to me email? LOL, damn I'm stoned...

talking to anyone that wants to know more about RO water and pH buffers. I sure did learn a lot from them and was sharing.

 

[GrnMan]

Hey email, what do you think about RO water as opposed to using tap water for your plants? I think plants miss out on what minerals tap water has to offer.

 

[email468]

i agree that you'll need to be more careful feeding with RO and you'll use more nutrients than with hard tap water.

i recently switched from tap to RO. i grow hydro and the only nutrient brand i could find to support my hard water (over 250 PPM) was General Hydroponics 3-part Flora series (the micro came in a hardwater version). Now that I am using RO, I can use any brand I want and at higher strengths.

Having said that - i've gotten great results and am very pleased with using GH 3-part hardwater version with tap water.

But I am no expert and you may experience different results.

 

[Bain]

So I read through those two links... wow lots of info for a new grower but I think I absorbed a decent amount of it.

One thing I noticed was
"All these instructions, are for meters designed to be left in the solution full time."

Seeing that Earl is a hydro guy, and mentions his directions are for hydro only meters, would the rule that RO water damages meters still apply to soil meters? the cheapo that I have (and probably will return tomorrow) doesn't have the moisture controled probe that his does.

As for my needs, my plants are still under 2 weeks old so I'm not giving them nutes yet, just superthrive. I figured keeping in the 6.5-7 range would be a good thing to do to ensure a good start.

From what I've seen all the soil ph meters look like cheap pieces of junk. would you suggest getting a liquid ph tester and ph my water before using it and assume the soil ph is fine? Do you think a tds meter is important, or if I follow the directions on nutes with RO water will I be fine?

 

[email468]

i am also a hydro guy and don't feel qualified to answer all your questions. From my understanding, any pH meter with a bulb-style probe is susceptible to becoming not usable from RO water.

I can say less nutes is usually better. i highly recommend both a good quality pH and PPM meter but again - these are super important to hydro (though you can get by without them - it is a weed after all).

I think if you use a light hand with the nutes when following directions and listen to your plants you'll do fine.

 

[WWgrower]

RO water hurts ph meters???? I was thinking of getting a RO for my hydro this winter and was going to channel it through my ice maker also. We have terrible well water. So can you direct me to find out more about the damage it causes to meters? I know it is bad for septic systems if used in a fairly large scale. Did not know about meters though. Thanks

 

[email468]

RO water hurts ph meters???? I was thinking of getting a RO for my hydro this winter and was going to channel it through my ice maker also. We have terrible well water. So can you direct me to find out more about the damage it causes to meters? I know it is bad for septic systems if used in a fairly large scale. Did not know about meters though. Thanks

Here is my question and Earl's response...
https://www.rollitup.org/hydroponics-aeroponics/57961-simple-ppm-question-3.html#post644548

 

[Picasso345]

Never heard of it. RO is no different than very pure water so I can't imagine. I installed a RO system a few weeks ago to replace my well water and I'm very happy. It's running smooth. Water tastes great. PH is very consistently 8.0, so my meter isn't damaged yet. Plants seem very happy. With Fox Farm nutes and a little Superthrive the ph goes to about 6.1 and then a tiny pinch of baking soda I'm at 6.5 on the nose.

I'm already a little skeved out looking at the discoleration of the first filter. I never drank the well water before, but I did use it to cook. No more.

100 GPD Reverse Osmosis 6 Stage UV Ultraviolet purifier - eBay (item 320248312768 end time May-07-08 12:16:32 PDT)

 

[Picasso345]

Earl is speaking of water with a TDS of near 0. Doesn't matter if it is well water, RO water or my urine. Water near a TDS of zero will be less reliable. My RO only gets down to about 50 TDS, more than enough to get a reliable reading. I have zero worries. I store my meter is ph meter storage solution. I think this is worrying about nothing.

 

[LoudBlunts]

tds reading and ph readings are different


RO water barely has any ions to measure which is what ph measures....

over time they say it could (keyword being could....not saying it absolutely WILL happen, but could happen) affect the readings of the ph meter.

which is why you're suppose to only TDS/PPM test RO water.


this was told to me by the techs @ local water plant

 

[email468]

while it is most likely much ado about nothing - dude asked so i answered.

 

[Picasso345]

tds reading and ph readings are different


RO water barely has any ions to measure which is what ph measures....

over time they say it could (keyword being could....not saying it absolutely WILL happen, but could happen) affect the readings of the ph meter.

which is why you're suppose to only TDS/PPM test RO water.


this was told to me by the techs @ local water plant

Of course ppm and ph are different. I think the water techs are nuts. I'm going to risk my plants worrying about a ph meter that MAY or may not go bad. Pffft. I have bigger fish to fry.

 

[email468]

Of course ppm and ph are different. I think the water techs are nuts. I'm going to risk my plants worrying about a ph meter that MAY or may not go bad. Pffft. I have bigger fish to fry.

here is my understanding - your mileage may vary...

RO water can "deactivate" your pH meter but that doesn't really matter since you shouldn't be pH'ing your water until after you add nutrients anyway. And good luck getting an accurate pH reading from RO water anyway.

if the RO filter does not bring the PPM into a 000-005 range - time to get a new filter. Anything higher in PPM shouldn't really be considered RO water.

also note - what works for you may not work for every one. best to answer the questions as direct and with as much info as possible interjecting anecdote but not basing your entire response on it.

 

[Picasso345]

here is my understanding - your mileage may vary...

if the RO filter does not bring the PPM into a 000-005 range - time to get a new filter. Anything higher in PPM shouldn't really be considered RO water.

Time to adjust your understanding.

Quality of RO Product Water
The amount of dissolved solids in water produced by reverse osmosis is approximately a constant percentage of those in the feed water. For example, when the feed water contains 300 ppm total dissolved solids (TDS), the product water may have 15 to 30 ppm (95% and 90% rejection ratio respectively).

FDA itg Page 1

 

[KAOSOWNER]

I grow hydro and soil and wouldnt do either without a digital ph meter. The rapitest soil meters are just crap and have never read right to my knowledge. I do use a soil maoisture meter though, i dont know why because i really dont pay any attention to it. If you are using RO water and it reads high than add some ph down till it reads right. My question is how do you propose to do that with a soil ph meter? If anything at least get some litmus paper to test your water with and have found litmus paper to be pretty reliable even for testing your runoff. Ph is so crucial to nutrient uptake i wouldnt mess with growing without a digital meter. Also i have found my ppm meter useful in soil as well, not as useful as in hydro but it is nice to know how much food you are giving to your ladies.. And email i believe you are capable of answering most questions wether it is hydro or not, you are to modest............