pH of my reverse osmosis is 5.9

I just got a ph meter today. I calibrated with the 2 solutions it came with, then I made a few measurements. I took the soil to test and mixed it 1 part soil to 2 parts reverse osmosis water. These are my readings:

tap water = 7.3
RO = 5.9

perlite = 6.0
miracle grow = 6.3
fox farms happy frog = 5.5
soil from "jr" plant = 6.3

Is it normal for reverse osmosis water to be 5.9? Should I be adjusting it?

ro water should be nuetral if you have a good RO unit. Aparrently your RO unit is still leaving something in the water making it acidic.

I buy it at the super market in the "fill it yourself" station

My RO water comes out at 6.0. After mixing your nuits you should adjust the PH to between 6.3 to 6.8.

http://en.wikipedia.org/wiki/Soil_pH

I'm afraid im burning my plants with stuff so I switched to RO. I still am getting some of the nute burn looking symptoms on the lower leaves so I was going to hold off on using any nutes and just do plain RO for a bit. I am however feeding them cal-mag with every watering, nutes or not, because I think I had mg deficiencies last time (before I even switched to RO).

What should I be using to adjust my pH?

http://www.amazon.com/General-Hydroponics-pH-Up-Quart/dp/B000BT4IV2

Any brand of PH Up will do. Use an eye dropper, it doesn't take much. And wear rubber gloves because it's alkali and will burn your skin if you get any on you.

I can't be sure of what's wrong with your plant, but over feeding is probably the most common mistake of beginners.

ph ov ro water is 5.5. after its been standing for 12 hours 5.9 freshly made sounds about right

glShemp said:

I can't be sure of what's wrong with your plant, but over feeding is probably the most common mistake of beginners.

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I fed these ladies nothing but water for the first 3 weeks because the Happy Frog has some bat shit and worm poop in it to get them started. When I did start feeding I fed every other day at half strength and they look great. The few yellow spots are my fault from leaving drops of nutrient on the leaves from foliar feeding with the lights on. I'm gradually upping the strength of the nutrients now that they are past their one month birthday.

Point is, I'm being very conservative on feeding to prevent over feeding.

ckckck said:

ph ov ro water is 5.5. after its been standing for 12 hours 5.9 freshly made sounds about right

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He's in soil.

guy incognito said:

I just got a ph meter today. I calibrated with the 2 solutions it came with, then I made a few measurements. I took the soil to test and mixed it 1 part soil to 2 parts reverse osmosis water. These are my readings:

tap water = 7.3
RO = 5.9

perlite = 6.0
miracle grow = 6.3
fox farms happy frog = 5.5
soil from "jr" plant = 6.3

Is it normal for reverse osmosis water to be 5.9? Should I be adjusting it?

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Reverse osmosis units are great but they cannot and do not remove everything. Water is not a good buffer (meaning it doesn't resist pH changes and takes on the pH of whatever is in the water). There is nothing wrong with your water or your unit. You simply may need to adjust it with a little bit of pH up. If you want to learn a little more about the properties of water or learn how your reverse osmosis unit works you can click on the link in my sig. Happy growing!

ro unit do remove everything if a di resin is used i keep marine fish and my ro water has 0tds the purest water possible heres my little fishis lol and stop worrying about ur plants u remind me of mysely when i started worried about everything chill m8 remember its a weed

ckckck said:

ro unit do remove everything if a di resin is used i keep marine fish and my ro water has 0tds the purest water possible heres my little fishis lol and stop worrying about ur plants u remind me of mysely when i started worried about everything chill m8 remember its a weed

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DI resin will remove a little bit more of the shit that the r/o unit misses but trust me, it cannot possibly remove everything. Just because your TDS meter is reading zero doesn't mean that there is nothing in the water. It just means that a relatively inexpensive TDS meter isn't picking it up. I have an advanced degree in chemistry and used to work in a lab where we had really awesome reverse osmosis/DI units. Even though it read zeros with a TDS pen, I could still put it on the GC/MS and detect quite a few impurities. Your TDS meter will read zero but could still have .99ppm of dissolved solids present. Now, there is no doubt that it is very pure water but it is simply impossible to remove 100% of the impurities in water, even with the most expensive, advanced water purifiers available. This is why even the purest of water rarely reads 7.0 pH.

doc111 said:

Now, there is no doubt that it is very pure water but it is simply impossible to remove 100% of the impurities in water, even with the most expensive, advanced water purifiers available.

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what about distilled water? is it possible to distill water to 100% purity?

doc111 said:

DI resin will remove a little bit more of the shit that the r/o unit misses but trust me, it cannot possibly remove everything. Just because your TDS meter is reading zero doesn't mean that there is nothing in the water. It just means that a relatively inexpensive TDS meter isn't picking it up. I have an advanced degree in chemistry and used to work in a lab where we had really awesome reverse osmosis/DI units. Even though it read zeros with a TDS pen, I could still put it on the GC/MS and detect quite a few impurities. Your TDS meter will read zero but could still have .99ppm of dissolved solids present. Now, there is no doubt that it is very pure water but it is simply impossible to remove 100% of the impurities in water, even with the most expensive, advanced water purifiers available. This is why even the purest of water rarely reads 7.0 pH.

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hmm ok i thought 0 tds meant nothing got through and its pure what gets through then if its reading 0tds not trying to be a dick just interested manythanks

irieie said:

what about distilled water? is it possible to distill water to 100% purity?

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Reverse Osmosis is the best way to purify water. Good RO water is more pure than distilled.

doc111 said:

Reverse osmosis units are great but they cannot and do not remove everything. Water is not a good buffer (meaning it doesn't resist pH changes and takes on the pH of whatever is in the water). There is nothing wrong with your water or your unit. You simply may need to adjust it with a little bit of pH up. If you want to learn a little more about the properties of water or learn how your reverse osmosis unit works you can click on the link in my sig. Happy growing!

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already read all about your thread. That's the reason I decided to ditch tap water and go full on RO for this grow (that and several dead plants). I'm sick of my plants getting sick in the flower stage for no apparent reason

Kerovan said:

Reverse Osmosis is the best way to purify water. Good RO water is more pure than distilled.

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no offense but i was asking doc111. i am looking for a scientific answer not your opinion, thanks though.

glShemp said:

http://www.amazon.com/General-Hydroponics-pH-Up-Quart/dp/B000BT4IV2

Any brand of PH Up will do. Use an eye dropper, it doesn't take much. And wear rubber gloves because it's alkali and will burn your skin if you get any on you.

I can't be sure of what's wrong with your plant, but over feeding is probably the most common mistake of beginners.

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anything like ph up is a dangerous idea with pure water. There are no buffering agents in the water which can make for some dangerous ph swings. Hence why aquarium keepers add buffers back into the water to keep the ph stable.

irieie said:

what about distilled water? is it possible to distill water to 100% purity?

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Distillation is probably going to get you the closest to absolute purity. Nothing can completely remove all impurities, although the amounts of said impurities becomes trivial at those levels.

ckckck said:

hmm ok i thought 0 tds meant nothing got through and its pure what gets through then if its reading 0tds not trying to be a dick just interested manythanks

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Think of it this way. I can magnify a specimen with a microscope, we'll say bacteria. Bacteria are absolutely invisible to the naked eye, yet with a microscope at 10,000x magnification I can see them in pretty good detail. The same goes for impurities. Your TDS pen is quite an invention but it works by passing current between 2 points and is only capable of giving you an estimate of the total dissolved solids in the PPM (parts per million) range. It sends a known voltage from one electrode to another, and the less dissolved solids in the water, the less voltage makes it to the receiving electrode. The pen then uses an algorithm to give you an estimate of the Total Dissolved Solids in your water. With more sophisticated measuring equipment I can get down in to PPB (parts per billion) and even PPT (parts per trillion). Nothing is ever absolutely pure. The constantly decaying atoms and subatomic particles crashing into one another help see to that as well.

irieie said:

no offense but i was asking doc111. i am looking for a scientific answer not your opinion, thanks though.

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No offense taken. But how is his opinion any better than mine? just because somebody "says" they are an expert on the internet does not make it true. google distilled vs reverse osmosis for more answers..