slurry test ratio problem

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kenmastazz

Well-Known Member
Hi,

i would like to measure my soil ph and tried the slurry test but unfortunately the soil:water 1:1 ratio is just a little moist soil there is no soil water to read the ph from?
I tried a ratio of 1 part soil and 2 parts RO water with fresh biobizz allmix soil and after stirring for a few minutes and let it sit for 30min i read 5.7 but the bag says 6.6!

I have a deficiency and Im pretty sure its because of low pH in my soil. I tested the runoff and it was <5 before panicking I tried the more accurate slurry test but like i said i need to be sure my readings are correct.....is it possible that different charges have different pH and i catched a bad charge??
 
Richard Drysift

Richard Drysift

Well-Known Member
I could never get an accurate check on ph in the soil via a slurry test. You need a decent quality soil probe to get an accurate ph at the root zone. Blue lab is good; there are cheapo models that usually check moisture level too. Those are junk; don't waste your money.
Hard to believe that bagged soil would have a ph imbalance as it is. Just because runoff/slurry says it is 5.7 does not mean that is the actual ph in the rhizosphere....What kind of issues are you having with your plants?
 
V

VONDANK420

Member
kenmastazz said:
Hi,

i would like to measure my soil ph and tried the slurry test but unfortunately the soil:water 1:1 ratio is just a little moist soil there is no soil water to read the ph from?
I tried a ratio of 1 part soil and 2 parts RO water with fresh biobizz allmix soil and after stirring for a few minutes and let it sit for 30min i read 5.7 but the bag says 6.6!

I have a deficiency and Im pretty sure its because of low pH in my soil. I tested the runoff and it was <5 before panicking I tried the more accurate slurry test but like i said i need to be sure my readings are correct.....is it possible that different charges have different pH and i catched a bad charge??
Click to expand...
I'm not surprised if it is low straight out of the bag. Many manufactures mixed dont have enuff lime to counter the acidity of peat or coco or both.
Fill a cup w holes in the bottom full of the mix and pour some RO thru it and collect. You won't need a lot of runoff. Check the runoff and if its still acidic you know where the problem lies....
 
K

kenmastazz

Well-Known Member
Richard Drysift said:
I could never get an accurate check on ph in the soil via a slurry test. You need a decent quality soil probe to get an accurate ph at the root zone. Blue lab is good; there are cheapo models that usually check moisture level too. Those are junk; don't waste your money.
Hard to believe that bagged soil would have a ph imbalance as it is. Just because runoff/slurry says it is 5.7 does not mean that is the actual ph in the rhizosphere....What kind of issues are you having with your plants?
Click to expand...
Biobizz allmix with grow, bloom,heaven. used epson salt twice
they have a lockout because im feeding them good but still they look hungry....
 

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piratebug

Well-Known Member
I would start adjusting your water or feed to have a pH of 6.8 to 7.0 with BB pH+ and BB pH-, cause somehow through your watering and feeding you have lowered the pH in your BB allmix to the point that the pH buffers in the soil can no longer keep the soils pH in the pH 6.2 to pH 6.6 range. So you either need to water / feed at pH 6.8 to pH 7.0, to offset the pH 5.7 the soil is reporting and causing a very bad zinc / sullfer / magnesium lockout, or add 2 tablespoons of dolomite lime per (1) gallon of allmix soil, (work it in with a fork), to raise the allmix soil to pH 6.4 from pH 5.7, and then you will always have to water / feed at pH 6.4 to keep the allmix soil where it needs to be. Also as a side note... the reason I said you would need to feed at pH 6.8 to pH 7.0 if you are just using the BB pH up+/down- without adding the dolomite lime to your allmix, because if your allmix is reporting a pH of 5.7, feeding at pH 6.8, will raise the allmix pH 5.7 reading to pH 6.2, where the start of the best pH range is when growing in a medium like allmix. But if you want the allmix pH 5.7 to be in the sweet spot then you would need to water / feed at pH 7.0 to raise the allmix pH 5.7 to pH 6.4.
 
V

VONDANK420

Member
piratebug said:
I would start adjusting your water or feed to have a pH of 6.8 to 7.0 with BB pH+ and BB pH-, cause somehow through your watering and feeding you have lowered the pH in your BB allmix to the point that the pH buffers in the soil can no longer keep the soils pH in the pH 6.2 to pH 6.6 range. So you either need to water / feed at pH 6.8 to pH 7.0, to offset the pH 5.7 the soil is reporting and causing a very bad zinc / sullfer / magnesium lockout, or add 2 tablespoons of dolomite lime per (1) gallon of allmix soil, (work it in with a fork), to raise the allmix soil to pH 6.4 from pH 5.7, and then you will always have to water / feed at pH 6.4 to keep the allmix soil where it needs to be. Also as a side note... the reason I said you would need to feed at pH 6.8 to pH 7.0 if you are just using the BB pH up+/down- without adding the dolomite lime to your allmix, because if your allmix is reporting a pH of 5.7, feeding at pH 6.8, will raise the allmix pH 5.7 reading to pH 6.2, where the start of the best pH range is when growing in a medium like allmix. But if you want the allmix pH 5.7 to be in the sweet spot then you would need to water / feed at pH 7.0 to raise the allmix pH 5.7 to pH 6.4.
Click to expand...
Your spot on with recommending the dolomite if the soil is acidic but raising the PH of feed/water without the dolomite would take an extreme amount of solution to move the PH in the medium up. Were talking about the molarity of a volume of an acidic semi-solid medium vs the alkaline/base molarity of a liqued.
But like you said, if the medium is acidic add dolomite.
 
K

kenmastazz

Well-Known Member
piratebug said:
I would start adjusting your water or feed to have a pH of 6.8 to 7.0 with BB pH+ and BB pH-, cause somehow through your watering and feeding you have lowered the pH in your BB allmix to the point that the pH buffers in the soil can no longer keep the soils pH in the pH 6.2 to pH 6.6 range. So you either need to water / feed at pH 6.8 to pH 7.0, to offset the pH 5.7 the soil is reporting and causing a very bad zinc / sullfer / magnesium lockout, or add 2 tablespoons of dolomite lime per (1) gallon of allmix soil, (work it in with a fork), to raise the allmix soil to pH 6.4 from pH 5.7, and then you will always have to water / feed at pH 6.4 to keep the allmix soil where it needs to be. Also as a side note... the reason I said you would need to feed at pH 6.8 to pH 7.0 if you are just using the BB pH up+/down- without adding the dolomite lime to your allmix, because if your allmix is reporting a pH of 5.7, feeding at pH 6.8, will raise the allmix pH 5.7 reading to pH 6.2, where the start of the best pH range is when growing in a medium like allmix. But if you want the allmix pH 5.7 to be in the sweet spot then you would need to water / feed at pH 7.0 to raise the allmix pH 5.7 to pH 6.4.
Click to expand...
Thanks!!
there is misunderstanding in order to see if the slurry test is accurate I took some fresh soil from the bag and made a slurry test and it came out 5.7! the bag says 6.6.

I made a „real“ slurry test used some plant soil and it came out 6. Now 6 is not that bad BUT I’m not sure if it’s correct I „failed“ the fresh soil test, either I made a mistake or the reading was accurate and the fresh soil is not prepared right ?!
i ordered the bluelab soil ph pen is that any good ?
 
Kingrow1

Kingrow1

Well-Known Member
kenmastazz said:
can you give me some practical advise please. I put away all my meters what now :)?
Click to expand...
I cant solve your problems but fussing over soil ph and meters in the way of hot lights is wrong and two easy things to correct for next grow. Start in a small pot and repot up save bother of adding ferts for first half of the grow.

Just keep it simple and environment is gona be like90% of your problem making you think ph and stuff.

Complete twenty more grows youll be fine :-)
 
K

kenmastazz

Well-Known Member
Kingrow1 said:
I cant solve your problems but fussing over soil ph and meters in the way of hot lights is wrong and two easy things to correct for next grow. Start in a small pot and repot up save bother of adding ferts for first half of the grow.

Just keep it simple and environment is gona be like90% of your problem making you think ph and stuff.

Complete twenty more grows youll be fine :-)
Click to expand...
i have 99 problems but the environment aint one!
Everything you said i did i started in party cups lightmix and repotet after a few weeks to 9l allmix.
After flip my temperatur 24-25° with lights on 21° without and rh 45-50%.
My tapwater is 7.5 after nutes 6.4-6.5 and i water every 3-4 days depending on the weight...never used ph regulator

What else ?
 
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