pH Question

jjf1978

jjf1978

Well-Known Member
Ok so I have some Fafard potting soil shown in the picture I attached. It says that it has a balanced pH. It does not say the pH value.

I wanted to find out what the pH of the soil is so this is what I did.

Took some of the soil and put it in a 52 ounce cup with holes punched in the bottom. Ran some tap water with a pH of 7.0 through it for a minute and collected a good sample of runoff. I then tested the runoff sample and it came out to be around 5.1-5.3 pH. That is pretty acidic so I tested again, and again, and one more time. Same result.

I have a bunch of clones in the same soil. I never fertilized them. Did the same runoff test and came up with a pH of 6.0 - 6.3!

I have a few plants flowering for around 6 weeks in the same soil. I've fed these plants about 4-5 times with a fertilizer solution containing a pH of 6.2. For every one feeding I have been watering two times following with tap water of pH 7.0. The last time I watered with the plain 7.0 tap water I captured some runoff and tested it. Their pH came out to around 5.8 - 6.0.

Now my clones are doing great, healthy growth, no weird pH problems, no twisted leaves or anything just nice solid growth.
My flowering plants are doing good, I feel the buds could be a bit bigger so I was wondering if the low pH was locking out potassium and other elements.

Questions

  1. Would they do good if the soil pH was really 5.0?
  2. Is the reading of 5.0 correct? The runoff from the soil is 5.0 but does that mean the soil is 5.0?? I'm guessing the combination of the 7.0 water + some value of the soil added together made it 5.0?
  3. If the runoff is 5.0, what is the actual pH value that the roots are living in?
  4. If the plant is actually living in a 5.0ish pH why is it doing so good? I read MJ in soil should be around 6.5.
  5. How can pH start out at 5.0 and then rise to 6+ after watering? Did the 7.0 pH water eventually raise the soil pH after leaching it so many waterings?
:leaf: Thanks in advance :leaf:
 

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riddleme

riddleme

Well-Known Member
You want what they call a soil mix, it can vary as different people do it different ways. The best info can be had by googling "container gardening" look for soil mixes for tomatoes :bigjoint:

If you read much here, you will see a lot of folks use Fox Farms Ocean Forest (I do) it is a "hot" soil that already has lots of nutes in it (good for 3 to 4 weeks)

The 2 basic ingredients you want to add to your soil are peat moss and dolimite lime, they help the soil buffer the ph over time, which is important once you start adding nutes, as they will tend to lower your ph more
 
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passerbye

Well-Known Member
um.....peat moss has a ph of 4.5-5.0 on average. It doesnt buffer.

Dolomite does tho. It is ph7 nuetral and will raise ph if lower than 7.

I only know this cuz I use a high peat soil and have to add hydrated lime to get the ph up before planting.

Go to lowes and get hydrated lime if you want to bring ph up.

Easy way to know. If you are sure u have enough nutes in there, u should see a slight burn on the end of your shade leaves. If it isnt there, they arent getting max nutes. If you keep adding nutes and still dont see a burn, then u might have nute lock up.

Another good thing: use a weak solution (if it says 1 tablespooon/gallon use 1/4 teaspoon) and foiler feed. If they respond in a day by darkening up, they need more nutes. If u test the soil and you have a lot in there but no burn and lime green leaves, u r locked up.

hydrated lime will slowly raise the ph. If you ph up more than .5 per day, u could nute burn them.
 
jjf1978

jjf1978

Well-Known Member
passerbye said:
um.....peat moss has a ph of 4.5-5.0 on average. It doesnt buffer.

Dolomite does tho. It is ph7 nuetral and will raise ph if lower than 7.

I only know this cuz I use a high peat soil and have to add hydrated lime to get the ph up before planting.

Go to lowes and get hydrated lime if you want to bring ph up.

Easy way to know. If you are sure u have enough nutes in there, u should see a slight burn on the end of your shade leaves. If it isnt there, they arent getting max nutes. If you keep adding nutes and still dont see a burn, then u might have nute lock up.

Another good thing: use a weak solution (if it says 1 tablespooon/gallon use 1/4 teaspoon) and foiler feed. If they respond in a day by darkening up, they need more nutes. If u test the soil and you have a lot in there but no burn and lime green leaves, u r locked up.

hydrated lime will slowly raise the ph. If you ph up more than .5 per day, u could nute burn them.
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I haven't had any nutrient burn using this soil. I will go and buy some dolomite lime add it to my test soil and see what the pH of the runoff is with the lime. Do you add it to your water or to the soil itself?
 
Normajean1

Normajean1

Well-Known Member
soil itself. you can water in the soil for a quick ph problem fix. i never new about adding dolomite lime to the soil itself till i searched it on this site yesterday. you wanna add 1 tablespoon to each gallon of soil your using. i think
 
DaveCoulier

DaveCoulier

Well-Known Member
passerbye said:
um.....peat moss has a ph of 4.5-5.0 on average. It doesnt buffer.

Dolomite does tho. It is ph7 nuetral and will raise ph if lower than 7.

I only know this cuz I use a high peat soil and have to add hydrated lime to get the ph up before planting.

Go to lowes and get hydrated lime if you want to bring ph up.

Easy way to know. If you are sure u have enough nutes in there, u should see a slight burn on the end of your shade leaves. If it isnt there, they arent getting max nutes. If you keep adding nutes and still dont see a burn, then u might have nute lock up.

Another good thing: use a weak solution (if it says 1 tablespooon/gallon use 1/4 teaspoon) and foiler feed. If they respond in a day by darkening up, they need more nutes. If u test the soil and you have a lot in there but no burn and lime green leaves, u r locked up.

hydrated lime will slowly raise the ph. If you ph up more than .5 per day, u could nute burn them.
Click to expand...
Dolomite does not have a ph of 7.0. Its more around 8.4. I have some and tested it myself.

People automatically think its neutral ph because everyone says it buffers the soil. What they really mean is it helps to buffer acidic soils.

I really disagree with you saying that nute burn on leaves is necessary for them to get max nutes. They get burned because they have too much. You can have very healthy plants without any signs of nute burn. I dont know where you got this idea.

Hydrated lime will not slowly raise your ph either. That stuff is extremely alkaline. Over 12 on the ph scale.

The only time its useful is if you have very acidic soil and need to raise your ph quickly. Dolomite lime is more slow acting and less harmful on your plants in case you over do it.

I would avoid everyone to never use the shit and get dolomite lime.

JJ: Most people add dolomite lime to the soil before putting any plants in it. If theres is no dolomite lime in it, then use 1 tablespoon per gallon. If it already has lime in it, go with 1 teaspoon. If all your plants are healthy and strong right now, I wouldn't get too worked up over bumping up your ph. Just go ahead and add a bit of lime to your next soil mixture and use it for your next transplant or next clones/seeds.

You can introduce it by topdressing and then watering. Or you can mix it up with water and just water. I think I used one teaspoon per gallon of water last time, but its not very water soluble, so you'll need to mix it up real good.
 
jjf1978

jjf1978

Well-Known Member
DaveCoulier said:
JJ: Most people add dolomite lime to the soil before putting any plants in it. If theres is no dolomite lime in it, then use 1 tablespoon per gallon. If it already has lime in it, go with 1 teaspoon. If all your plants are healthy and strong right now, I wouldn't get too worked up over bumping up your ph. Just go ahead and add a bit of lime to your next soil mixture and use it for your next transplant or next clones/seeds.

You can introduce it by topdressing and then watering. Or you can mix it up with water and just water. I think I used one teaspoon per gallon of water last time, but its not very water soluble, so you'll need to mix it up real good.
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Yeah I did not add it to the original soil mix before planting :dunce: - now I know. The plants are doing "OK" i would say. Showing some minor deficiencies and I think it's because the low pH is locking out a few nutrients.

I don't want to feed again. I want to get the pH up to 6.5 and hope the plants start to absorb the nutrients in the soil.

Also I've read watering with molasses in place of plain tap waterings between feedings is good to do in the 5-6th week of flowering. Isn't molasses a pretty acidic solution? Do you have to pH up it?
 
DaveCoulier

DaveCoulier

Well-Known Member
Molasses is acidic. Im not sure how much affect it'll have on a gallon of water though. You can use it during veg as well. It feeds microbes in the soil, and provides some potassium and trace minerals.
 
jjf1978

jjf1978

Well-Known Member
DaveCoulier said:
Molasses is acidic. Im not sure how much affect it'll have on a gallon of water though. You can use it during veg as well. It feeds microbes in the soil, and provides some potassium and trace minerals.
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I mixed 1 Tablespoon with 1 gallon of water and I did my little pH dripper color changer thing and it look like it read at like 5.0 pH. I'm guessing the brown color of the molasses screws up the color of solution? Is it better to use the test strips? I need to get some of those lol.
 
jjf1978

jjf1978

Well-Known Member
DaveCoulier said:
Shell out $30 bucks for a Hanna digital tester.

This one Ive been told is pretty good for a cheaper model:

http://www.eseasongear.com/hahi98phphte.html

But if you can't, seems like it'd be better to use the test strips.
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sweet, didn't realize you could get one for $30! I saw a bunch for like $150 and was like screw that. But to get a digital readout and not have to ask my wife what color she sees is worth the $30 bucks lol
 
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passerbye

Well-Known Member
Durrr. So much for getting stoned and posting in the forums!

My apologies. Dave is correct. Hydrated lime and dolomite lime should not be used by most people.

What I referred to as dolomite and hydrated lime is in fact a modified form of dolomite called "Garden Lime". I have attached a pic. It is ph neutral at 7.0 and is very safe. I used it to balance my high peat soil and to soothe down low ph TigerBloom.

It is mixed in the soil, but you can dissolve it in warm water for a ph boost.

As far as the nute burn, I think we speak of different things. I said SLIGHT BURN on the TIPS OF the SHADE LEAVES.

I attached 2 pics. First shows the tip burn, but it is not as much as I usually do. Pic2 is nute burn you never want to see.

IME, seeing that burned tip is the plant telling me, "OK I am full. Keep feeding me like this and I am gonna puke." And then you back off the concentration.

Plants load up on nutes to last to the end. I want them maxed out. When I do this, I get bigger buds and better yields.

I explained this to a friend, who played it safe like Dave speaks of. He let me nute up 3 of his girls and within a week there was a noticeable difference. We then started nuting up all of them. At the end he said it was the highest yield he had ever gotten, almost double what he usually does.

I am a rebel. I push the envelope. I flirt on the end of disaster. But I get bigger buds and nicer weights. Is this for newbies or nervous ppl? Probably not.

Forums are about exchanging experiences. Take what you read and use it how you will. Playing it safe is cool. But as I have seen many times, and its true. This is a weed and its pretty hardy. Yes I burn a couple of shade leaves. Yeah I aint smokin those anyway and the bubble bag dont care much about those burnt tips either.
 

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DaveCoulier

DaveCoulier

Well-Known Member
passerbye said:
Durrr. So much for getting stoned and posting in the forums!

My apologies. Dave is correct. Hydrated lime and dolomite lime should not be used by most people.

What I referred to as dolomite and hydrated lime is in fact a modified form of dolomite called "Garden Lime". I have attached a pic. It is ph neutral at 7.0 and is very safe. I used it to balance my high peat soil and to soothe down low ph TigerBloom.

It is mixed in the soil, but you can dissolve it in warm water for a ph boost.

As far as the nute burn, I think we speak of different things. I said SLIGHT BURN on the TIPS OF the SHADE LEAVES.

I attached 2 pics. First shows the tip burn, but it is not as much as I usually do. Pic2 is nute burn you never want to see.

IME, seeing that burned tip is the plant telling me, "OK I am full. Keep feeding me like this and I am gonna puke." And then you back off the concentration.

Plants load up on nutes to last to the end. I want them maxed out. When I do this, I get bigger buds and better yields.

I explained this to a friend, who played it safe like Dave speaks of. He let me nute up 3 of his girls and within a week there was a noticeable difference. We then started nuting up all of them. At the end he said it was the highest yield he had ever gotten, almost double what he usually does.

I am a rebel. I push the envelope. I flirt on the end of disaster. But I get bigger buds and nicer weights. Is this for newbies or nervous ppl? Probably not.

Forums are about exchanging experiences. Take what you read and use it how you will. Playing it safe is cool. But as I have seen many times, and its true. This is a weed and its pretty hardy. Yes I burn a couple of shade leaves. Yeah I aint smokin those anyway and the bubble bag dont care much about those burnt tips either.
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I dont mean to keep busting your balls, but Epsoma garden lime is the same thing as Dolomitic Lime. It says so right on the back :)

Ive yet to see a 7.0 lime.
 
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passerbye

Well-Known Member
A specialized, pelletized lime made from dolomite. "Safer than hydrated lime" all written on the back. Are u just out to make me look bad Sir? I have an ex wife to do that for me ya know.

I said, "What I referred to as dolomite and hydrated lime is in fact a modified form of dolomite called "Garden Lime". You are splitting hairs here Dude! I disagree. It is not JUST LIKE dolomite. It is a safer, special form of it. I think Dave needs to smoke some of my herb. It makes one less worried about such trivial details. Argue all u want. If you have soil with low ph, it brings the ph up in a safer way.

Bust my balls all u want, just dont bust in on my grow! hehehe

I mix 2 tbsp per gallon and it measures 7 on my ph. I added it to all of my soil and it raised, uh I mean buffered my acidic soil. Turned my 2 lime green girls to a healthier green. It is way better than baking soda and cheaper than ph up.

Dang I aint argued this much with a dude since my brother when we were kids. Bro, is that you?!? bahahahahaha
 
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passerbye

Well-Known Member
The soil pH is a measure of the active soil acidity or alkalinity based on a scale from 1 to 14. A simple explanation of soil pH is that it is a measure of the concentration of hydrogen ions in the soil. The higher the concentration, the more acidic the soil is. On the pH scale, 1 is very acidic and 14 is very alkaline. Many of you have seen the chart that shows the availability of elements essential to plant growth at different soil pH levels. Some of the macro elements such as nitrogen, potassium, sulfur, and calcium, don't become fully available to the plant until the soil pH is 6.0. Some elements such as phosphorus and magnesium need a soil pH of 6.5 before they are fully available.

Lime neutralizes hydrogen ions, causing soil pH to increase. Lime nuetralizes otherwise acidic soil. Not all soils respond to a given lime application in the same way. Some soils have the ability to buffer (or resist) changes in soil pH by releasing hydrogen ions that are held on soil particles. Other soils have a lower capacity to release hydrogen ions. Soils that have a higher buffering capacity require more lime to reach a certain, desired, soil pH level as compared to soils with a lower buffering capacity. Therefore, it is necessary to monitor the ph of the soil to insure proper ph levels and it should not be automatically assumed the amount of lime applied will have the desired effect unless a ph buffer soil sample is taken first to provide exacting lime application.
All limestone materials are not equal. Some limestone materials have a higher ENP than others. Some limestone materials are dolomitic, meaning that they also contain magnesium.

Hydrated lime is preffered for it's quick solubility. Flour or Fine Dolomite Lime is not as water soluble and therefore will take longer for intergration into the soil medium.
 
jjf1978

jjf1978

Well-Known Member
I went out and bought some Lime. It isn't Dolomite lime, I could not find Dolomite Lime but I hope this will do. It says "Fast Acting" Lime, I put up a picture of it.

So I ran some tests with the Lime. The picture shows the results but they are bad pictures and the colors looked a little different in real life, so I need a digital soon as I can get one.

I got some bottled water and pH tested it and it came out around 7.0. I pinched a bit of lime from the bag and added it to the water and pH tested that and it came out to around 8.0+

I then took the normal 7.0 pH bottled water and ran it through the soil and collected a runoff sample and came up with around 5.0 - 5.3 pH

I then took the bottled water with Lime sample and ran that through the soil and the runoff pH came out to around 6.0 or so. Picture looks like 5.8 ish but in reality it looks liek 6.5 so I'm gonna say 6.0 average lol.

Either way the lime did raise the pH as expected. Now I have to decide what to do. Do I water a few times with lime added water to hopefully raise the overall pH of the soil? Or do I just add Lime to my watering / feeding / molasses solutions to bump the base pH up a bit? Hmmm...any suggestions?
 

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jjf1978

jjf1978

Well-Known Member
DaveCoulier said:
I would just water with lime added to it, then periodically check your ph every two weeks, and use it again if necessary. Using it too often in a short period of time could raise it too much.

Heres a link I found that talks about your lime:

http://diyorganiclawncare.blogspot.com/2009/05/encap-fast-acting-lime-review.html

It says Encap lime, but your lime is Encap, just repackaged under a different name.
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Thanks for the info! I'm going to just water it once as you suggested with the Water/Lime solution and leave it at that. I'll see how the plants respond and then maybe on the next watering do a molasses.

Not going to add any fertilizer for a little. There has to be some available for them in the soil. I'll worry about fertilizer later when I'm happy with the soil pH level.
 
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