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using alkalis for pH up

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blackmore View Drop Down
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  Quote blackmore Quote  Post ReplyReply Direct Link To This Post Topic: using alkalis for pH up
    Posted: 10 January 2008 at 17:59
high

got a question

I dont have access to a pH up or down packaged solutions here where i live.
but i do have easy access to concentrated sodium hydroxide.
Am trying to source some KOH, as ive read its preferred over NaOH.
How do i go about  increasing my pH using using them?

My pH is currently alittle too acidic 5.8

should i use water with my desired pH or
Should i use water with an alkaline pH (7.5) to get the pH to settle around 6.5?
I guess im trying to ask whether pH averages out

thanks
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  Quote Ganja Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2008 at 19:18
Soil is better at regulating its own pH than hydro mediums, which is why hydro gardeners have to be more exact about pH (and also keep it lower).

From reading the nutrient tank in the Museum over the years, it seems that when water's pH is lowered with nitric acid, it rises by itself overnight. A tank that was adjusted to pH 5.7 will commonly be at pH 6 when measured the next morning.

This can climb higher when the hydro plants drain their water back into the tank (I think rockwool has some effect on pH that I don't quite understand), but it also happens when no nutrient water is recirculated to the tank.

In short, if you're growing in soil, pH5.8 is a bit too low, but as long as your plants aren't suffering or visibly unhealthy, it's probably not too much of a worry.

Is the reading of pH 5.8 from the soil itself, or of the water that runs from the pot?

IN hydro mediums, pH 5.8 is fine.


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  Quote blackmore Quote  Post ReplyReply Direct Link To This Post Posted: 10 January 2008 at 19:46
hey ganja,
thanks for the fast reply,

having a background in chem, I can definately see the logic behind soils resillience towards pH shifting. Soil is not an efficient ionization medium as compared to hydro.
The hydro medium will reach equillibrium much faster (exponentially) than soil as its much more efficient ionically, hence more easily controllable.

I can forsee that i will have to water with corrected pH water for some time to get the soil to settle at my desired pH.

my question is, how do i go about pH correction in soil using alkalis?

getting pH up and down packaged solutions really isnt possible here where i live, so i have to make do.

btw, the pH reading of 5.8 was from the run off water.
watering water pH was 6.7
My soil is a peatmoss substrate. Which i know to be acidic by nature.
Seems to progressively get more and more acidic.
My plants are showing various symptoms, but its not life threatening at this stage.
i am worried, as they are all sharing common symptoms ranging from Ca, Mg def to Macro def. Is a nutrient lockout possible at this pH?
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  Quote Ganja Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2008 at 10:34
This is just the first reference I came across.

Most google results mention lime as the main way to raise soil pH.


Raising soil pH to make it more alkaline

It is generally easier to make soils more alkaline than it is to make them more acid.

Because different soil types react in different ways to the application of lime you will have to add more lime to clay soils and peaty soils than you will in sandy soils to achieve the same result.

To increase your pH by 1.0 point and make your soil more alkaline.

Add 4 ounces of hydrated lime per square yard in sandy soils

Add 8 ounces of hydrated lime per square yard in loamy soils

Add 12 ounces of hydrated lime per square yard in clay soils

Add 25 ounces of hydrated lime per square yard in peaty soils

Correction of an overly acid soil should be considered a long term project, rather than trying to accomplish it in one year. It is better to test your soil each year and make your adjustments gradually. The addition of hardwood ash, bone meal, crushed marble, or crushed oyster shells will also help to raise the soil pH.

[from http://www.thegardenhelper.com/acidsoil.html ]

There's also a nice table here:
http://web.ukonline.co.uk/fred.moor/soil/ph/p0103.htm

Googling 'raising soil pH' will give you a page of results much like the above.
"raising soil pH cannabis" might be even better.

The problem with changing soil pH is that it's hard to do with a liquid. Most advice requires the grower to dig materials into the soil, which is usually not practical for plants in a pot or plants that are already well established in the ground.

Also, the effects of lime or "
small amounts of hardwood ashes or crushed oyster/egg shells" are slower to raise the pH than something like KOH. On the other hand, the pH of the soil is really changed by these materials, rather than being temporarily nudged one way or the other.

IIRC, lowering the pH of soil is more complex and takes longer. I can't recall the materials off the top of my head, but the basic idea is to encourage certain  bacteria to lower it.

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  Quote Jonney Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2008 at 13:16
head to a pet shop... you can get ph up or down (used for water in fish tanks) that's what i did!

my 2 cents anyway!!
"It is possible that a certain amount of brain damage is of therapeutic value."

Dr Paul Hoch
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  Quote blackmore Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2008 at 13:47
oh cool jonney, i will check the local pet store out.

hey ganja
thanks for looking this up.
ive tried before and have pretty much found similar "lime" methods predominantly.
which, as u pointed out, takes a much longer time, and is not easy at this stage (with the digging and what not)

alkalis seem to make sense since they will provide immediate but temporary results, so im speculating i will have to water a few times to get the pH to settle.
I will water with a pH of 7.5 to allow pH to settle around 6.5 (from 5.8)
It seems like the way to go, using alkalis. however my planned method isnt based on experience, so im hesitant.

according to your post above, 25 ounces of lime in peat soil. (pretty high concentration)
If i use water with a pH>8, will it initially damage my roots/plant before reaching equillibrium?
 
And can i add nutrients/ferts in my pH corrected soultion?
If not, how should i feed them? pH solution first, then ferts?


btw, ive delayed my pH altering plans based on ur previous post.
The plants are mostly healthy looking at this pH. i will monitor pH for another week to see if it gets more acidic. if it does, ill use NaOH to bring it back up.


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  Quote Solidopc Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2008 at 15:29
If i use water with a pH>8, will it initially damage my roots/plant before reaching equillibrium?
 
And can i add nutrients/ferts in my pH corrected soultion?
If not, how should i feed them? pH solution first, then ferts?
 
I've never checked the ph of my water before feeding, but i live in an area, where the water ph is quite good, at around 7.5.
 
If i leave the tap water standing for at least 24 hours, it will dechlroinate it, and lower the ph to about 7.
 
In my opinion, a ph of greater than 8, is not good for your plants at all. You should aim to get it around 6.5.
 
Also, you should ph your water after you have added nutes, otherwise the nutes themselves will change the ph.
 
What you should do is, let your water sit for 24 hours, so it can dechlorinate.
 
Then, add your nutes to this water, as needed. Then check the ph of it. You might find that the nutes, lower your higher tap water ph, all by themselves, and if they dont, you then, start to addyour ph down.
 
A warning about ph down. It is very very strong stuff. after all, its acid.
 
You only need tiny tiny ammounts to change the ph. The one time i used it, i didnt even have to put one drop of ph down in. I just dipped the little pippet in, and the liquid that was on the outside of it, was enough to lower ph to the desiered level.
 
You must be careful, as if you add too much and it goes too low, you have to throw the feed away, you cant go adding ph upto bring the ph back up, once you've used ph down to bring it down.
 
They dont react well together at all/
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  Quote Ganja Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2008 at 12:17
I'm hesitant to advise using hydro pH formulas to adjust the pH of soil, as it's a bit outside my area. Not to say it's bad, but I don't know enough about the short and long term effects (on plants, soil and pH) to wholeheartedly recommend it.

As for pH imbalance actually damaging roots and plants, it has to be quite a lot higher or lower in order to cause physical damage (well below 5 or well over 8). The tap water in Amsterdam is often around pH 8.2, and this does not cause damage to houseplants, or cannabis when watered straight from the tap.

The main issue with pH is the access to nutrients that it allows. A serious imbalance can stop plants from using nutrients that are available. But it takes a serious excursion into acid or alkaline to cause physical damage to roots.

BTW - in the hydro garden, we use nitric acid (HNO3 - 38%) to lower pH and potassium hydroxide (KOH - 10%) to raise it.

JFTR - even at 10%, the KOH seems more corrosive than the 38% HNO3.
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  Quote blackmore Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2008 at 15:11
hi ganja,

I didnt go through with the pH up yet. partly because the plants look 80-90% healthy.

I have another problem, though
They are losing their lower fan leaves at an alarming rate which worries me.
The leaves dont even yellow or anything. (some loss of colour in the leaf veins)
Still, im inclined to believe this is more of the result of flowering stress.
the plants are all really bushy. So it is mostly leaves that dont get any light.

Is this normal? I think each plant loses a set of fan leaves in 2 - 3 days.
plants are in their 2nd week of flowering

thanks
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  Quote mike Quote  Post ReplyReply Direct Link To This Post Posted: 20 February 2008 at 00:11

if i rember right each point on the ph is ten times either asidic or alkiline the the one next to it like 7.0 is ten times more asidic the 7.1 it is best in my exsperance to change the ph slowly other wise you realy shock your plants

help my plant's fell over and can't stand up
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