# water PH



## papheteer (Dec 6, 2013)

My tap water has a ph of 7.7. I use both nitrate and ammonia based fertilizers at very low dosage, about 1/8tsp per gallon and it doesnt really change the ph of the water. I guess my question is: is ph of 7.7 ok for irrigation water or is it best to use phosphoric acid and bring it down to 6-6.5? Thanks!!


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## ALToronto (Dec 6, 2013)

Our tap water is well buffered, so a small amount of fertilizer will not affect it. If you used RO water, you would see a very different result.

I use citric acid - dissolve 5 tsp of crystals in a cup of water, put the solution in a squeeze bottle and figure out how much to add to your watering container each time. Phosphoric acid will add phosphate to your water and will affect the nutrient balance.


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## papheteer (Dec 6, 2013)

Al, what type of water do you use then? How and what do you feed? And what do you adjust the ph to? Thanks a lot!


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## Stone (Dec 6, 2013)

7.7 is slightly alkaline. With that water you can afford to use a nitrate to ammonium ratio of about 80/20 or something like that and you shouldn't see great (or fast) pH changes in your P/mix. If you want to use higher nitrate, then you may need to use acid in your water. I use sulphuric but its really dangerous. :evil: I think a pH of 5.5 to 6 is good but I grew nice plants for years with pH of 9 and no nitrate. With all the lime in that water, pH of the mix still stabilised to around 6 with the ammonium and Urea.


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## ALToronto (Dec 6, 2013)

Are you growing only slippers or other orchids as well? Paphs won't mind a higher pH, phrags probably will. Phals and catts do better just below 7, and masdies need to be below 6.

I was not getting good growth with tap and even jug-filtered water. These ion exchange filters took water from 140 ppm to 117, so they didn't work nearly as well as advertised. So I put in an under-counter RO system (cost me $160 for 5-stage, faucet included), and now I have 10 ppm water. At this level of purity, a little fertilizer takes the pH from 7.6 to just under 7, so I no longer have to adjust pH. Until recently, I adjusted it for my living wall, as it's still leaching excessive calcium. By now unadjusted pH of runoff water is at 6.4, so I have stopped. 

I've been following Rick's advice to feed very, very little every time. For potted plants, I alternate between K-Lite and Neptune's Harvest, keeping both to 20 ppm N. For the living wall, I use a tiny amount of ammonia / urea based fertilizer with Epsom Salts, and once in a while I use K-Lite or NH.


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## papheteer (Dec 10, 2013)

Stone said:


> 7.7 is slightly alkaline. With that water you can afford to use a nitrate to ammonium ratio of about 80/20 or something like that and you shouldn't see great (or fast) pH changes in your P/mix. If you want to use higher nitrate, then you may need to use acid in your water. I use sulphuric but its really dangerous. :evil: I think a pH of 5.5 to 6 is good but I grew nice plants for years with pH of 9 and no nitrate. With all the lime in that water, pH of the mix still stabilised to around 6 with the ammonium and Urea.



Stone, thanks! Did you mean 80/20 ammonium to nitrate?


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## papheteer (Dec 10, 2013)

ALToronto said:


> Are you growing only slippers or other orchids as well? Paphs won't mind a higher pH, phrags probably will. Phals and catts do better just below 7, and masdies need to be below 6.
> 
> I was not getting good growth with tap and even jug-filtered water. These ion exchange filters took water from 140 ppm to 117, so they didn't work nearly as well as advertised. So I put in an under-counter RO system (cost me $160 for 5-stage, faucet included), and now I have 10 ppm water. At this level of purity, a little fertilizer takes the pH from 7.6 to just under 7, so I no longer have to adjust pH. Until recently, I adjusted it for my living wall, as it's still leaching excessive calcium. By now unadjusted pH of runoff water is at 6.4, so I have stopped.
> 
> I've been following Rick's advice to feed very, very little every time. For potted plants, I alternate between K-Lite and Neptune's Harvest, keeping both to 20 ppm N. For the living wall, I use a tiny amount of ammonia / urea based fertilizer with Epsom Salts, and once in a while I use K-Lite or NH.



I grow mainly slipper, Al. I tried using RO water with about 15-25% tap. It was too much work and I find that I get better growth with straight tap. 
I have been wanting to try Neptune's Harvest. Are you using the Kelp/Fish blend? Or the fish only? Also where do you buy it in Toronto? [email protected]


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## ALToronto (Dec 10, 2013)

I bought the fish/seaweed NH at Humber Nurseries, Hwy 50 @ Hwy 7. It's close to my work. In Toronto, you can buy it at Fiesta Farms, 200 Christie St., a little west of downtown.


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## Stone (Dec 10, 2013)

papheteer said:


> Stone, thanks! Did you mean 80/20 ammonium to nitrate?



NO, other way round.


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## papheteer (Dec 10, 2013)

ALToronto said:


> I bought the fish/seaweed NH at Humber Nurseries, Hwy 50 @ Hwy 7. It's close to my work. In Toronto, you can buy it at Fiesta Farms, 200 Christie St., a little west of downtown.



Thank you Al. The downtown location is a lot closer to me. I will give it a try! Heard good things about it. How does it smell though? Offensive?


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## papheteer (Dec 10, 2013)

Stone said:


> NO, other way round.



Thank you!


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## Rick (Dec 10, 2013)

What is the conductivity, alkalinity, and hardness?

pH is a very transitory value, and in low TDS waters the pH is highly influenced by gas balance. So you could sneeze on the water and drop the pH if it has very low buffer content.


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## ALToronto (Dec 10, 2013)

It smells, but not for long. I use it at 20 ppm N (1/4 tsp per litre), which is a lot less than label recommendations. You have to keep it in the fridge and never leave leftovers for another day - or you'll learn the true meaning of "offensive smell". I alternate it with K-Lite.


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## papheteer (Dec 11, 2013)

Rick said:


> What is the conductivity, alkalinity, and hardness?
> 
> pH is a very transitory value, and in low TDS waters the pH is highly influenced by gas balance. So you could sneeze on the water and drop the pH if it has very low buffer content.



Rick, here's our water analysis:

http://www1.toronto.ca/staticfiles/...D/DrinkingWaterAnalysisSummary_2012_FINAL.pdf


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## Rick (Dec 11, 2013)

papheteer said:


> Rick, here's our water analysis:
> 
> http://www1.toronto.ca/staticfiles/...D/DrinkingWaterAnalysisSummary_2012_FINAL.pdf



With a dash of N and P this water would be good to go with out using any comprehensive fert!

just a dash of ammonium nitrate and a drip of phosphoric acid:wink:

A kelp extract on top of the tap water by itself would probably do it.


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## papheteer (Dec 11, 2013)

That's really good to know. I really hate collecting RO water. I don't like wasting water. For the kelp, is it ok to use it every watering? And at what rate should i use it? Thanks a lot.


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## papheteer (Dec 11, 2013)

When using phosphoric acid, what ph should I shoot for? About 3 drops per gallon brings straight tap water to ph of 7.


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## Rick (Dec 11, 2013)

papheteer said:


> That's really good to know. I really hate collecting RO water. I don't like wasting water. For the kelp, is it ok to use it every watering? And at what rate should i use it? Thanks a lot.



I'd shoot for a total N of about 2-5 ppm if you are considering using it for daily watering. So need to know the NPK of your particlular Kelp mix (that may have some inorganic fert added for a boost) to figure out how much per gallon to use.

If you are watering primarily to organic media that pH is fine. That water is similar to middle TN tap water, and plenty of folks are getting great growth using it as a base. (I still think Ideal would be a 50% dilution with rain or RO water).

Do you have a big barrel to play with?


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## Rick (Dec 11, 2013)

papheteer said:


> When using phosphoric acid, what ph should I shoot for? About 3 drops per gallon brings straight tap water to ph of 7.



7 is fine.

What is the normality (or molarity) or your acid? Drops is a pretty meaningless unit without either knowing the stock concentration or the final P concentration in your irrigation water. You probably should try to hold final P to 1-5 ppm.

There's probably a good aquarium test kit available for that. I use Hach tests at work and the P test is a simple powder pillow with an indicator that turns shades of blue based on concentration.


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## papheteer (Dec 11, 2013)

Rick said:


> I'd shoot for a total N of about 2-5 ppm if you are considering using it for daily watering. So need to know the NPK of your particlular Kelp mix (that may have some inorganic fert added for a boost) to figure out how much per gallon to use.
> 
> If you are watering primarily to organic media that pH is fine. That water is similar to middle TN tap water, and plenty of folks are getting great growth using it as a base. (I still think Ideal would be a 50% dilution with rain or RO water).
> 
> Do you have a big barrel to play with?



Unfortunately I live in a condo so no big barrel. I mix my fertilizer solution in a 1 gallon container.


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## papheteer (Dec 11, 2013)

Rick said:


> 7 is fine.
> 
> What is the normality (or molarity) or your acid? Drops is a pretty meaningless unit without either knowing the stock concentration or the final P concentration in your irrigation water. You probably should try to hold final P to 1-5 ppm.
> 
> There's probably a good aquarium test kit available for that. I use Hach tests at work and the P test is a simple powder pillow with an indicator that turns shades of blue based on concentration.



You are right. All i know is the phosphoric acid i use is 85%. I will try and look for a test kit. Thanks again.


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## papheteer (Dec 11, 2013)

Searched online and found out that 85% phosphoric acid is 51% phosphorus. I used Ray's ppm calculator and it says i need .01 tsp/gallon of the phosphoric acid to give me 3 ppm of P. Now to figure out how many drops in an ml. Sorry for my primitive math.


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## Ray (Dec 12, 2013)

Had you scrolled a bit farther down my "Free Info" page from the calculator links, you'd see the one for conversion factors, telling you that a milliliter is 15.42 standard water drops.


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## papheteer (Dec 12, 2013)

Thanks, Ray. I did see that. But i assumed that every dropper and liquids are different so i tried to measure. Used a 1/8 tsp measuring spoon and took 22 drops from the eye dropper that i use to fill it up.


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## papheteer (Dec 12, 2013)

So if my math is right, it would take 2 drops (from my dropper) of phosphoric acid per gallon of water to achieve 3 ppm P.


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## ALToronto (Dec 12, 2013)

papheteer said:


> Thanks, Ray. I did see that. But i assumed that every dropper and liquids are different so i tried to measure. Used a 1/8 tsp measuring spoon and took 22 drops from the eye dropper that i use to fill it up.



That doesn't sound right. Are you sure it was 1/8 tsp? Even 1/8 tbsp would take less than 22 drops. I can see acetone or even pure alcohol having really tiny drops compared to water, but 85% phosphoric acid should be heavier than water, hence more surface tension and bigger drops. Are you letting each drop form and fall under its own weight?


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## Stone (Dec 12, 2013)

papheteer said:


> > For the kelp, is it ok to use it every watering?
> 
> 
> Kelpac recommends no more than every 10 days so the plant can complete its root initiation and start its growth cycle. Every 2 weeks is probably fine.


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## papheteer (Dec 12, 2013)

ALToronto said:


> That doesn't sound right. Are you sure it was 1/8 tsp? Even 1/8 tbsp would take less than 22 drops. I can see acetone or even pure alcohol having really tiny drops compared to water, but 85% phosphoric acid should be heavier than water, hence more surface tension and bigger drops. Are you letting each drop form and fall under its own weight?



Yup i used a 1/8 tsp. I also used an eye dropper. I did let each drop form.


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## Rick (Dec 12, 2013)

papheteer said:


> But i assumed that every dropper and liquids are different so i tried to measure.



The only thing that really dictates the size of a drop is the viscosity of the fluid (not the dropper configuration). 
For something the viscosity of water its 20 drops per ml.

Phosphoric acid is a little more syrupy, so I can see 15 drops per ml


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## Rick (Dec 12, 2013)

papheteer said:


> Yup i used a 1/8 tsp. I also used an eye dropper. I did let each drop form.




A full tsp is 5 ml hence a 1/8 tsp should be 0.625ml (and 12-13 drops of water)

When I used your 0.01ml of acid/gal I came out with just shy of 1 drop/gal to get that 3 ppm


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## papheteer (Dec 13, 2013)

Rick said:


> A full tsp is 5 ml hence a 1/8 tsp should be 0.625ml (and 12-13 drops of water)
> 
> When I used your 0.01ml of acid/gal I came out with just shy of 1 drop/gal to get that 3 ppm



I did try again today. Used a plastic pipette and it took about 12 drops of phosphoric acid to fill 1/8 tsp. Then I tried my dropper again (an empty eye drops bottle) and the drops are somewhat smaller and it took 23 drops to fill 1/8 tsp.


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## Rick (Dec 15, 2013)

papheteer said:


> I did try again today. Used a plastic pipette and it took about 12 drops of phosphoric acid to fill 1/8 tsp. Then I tried my dropper again (an empty eye drops bottle) and the drops are somewhat smaller and it took 23 drops to fill 1/8 tsp.



Weird Maybe the eye dropper is forcing the drops to fall before full gravity base drop formation.

I'd use the plastic pipette in this case since its closer to convention.


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## Trithor (Dec 15, 2013)

I would imagine that it is not only surface tension that plays a roll under these circumstances, but the 'cohesive' forces between the tip of the dropper and the fluid being dropped. My memory of physics and chem at varsity tells me that should not be true, but my gut tells me that there should be an influence.


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