how much dolomite lime to use

polo the don

Well-Known Member
A lot of people use 1tbsp per gallon of pro-mix. I've been doing this so long I don't measure anymore, I can just eyeball it, but that's me. When I did measure I used 1tBsp per gallon of pro-mix/perlite.
 

GOLDBERG71

Well-Known Member
A lot of people use 1tbsp per gallon of pro-mix. I've been doing this so long I don't measure anymore, I can just eyeball it, but that's me. When I did measure I used 1tBsp per gallon of pro-mix/perlite.
2 tablespoons per gallon equals 1 cup per cubic foot. Not perfectly but real close. So technically I think we are equal. Because the pro mix is only half my medium.
 

scunkworm

Active Member
Thanks guys for the replys and info, coz im in a rush to get my girls transplanted i used 1tsp of lime to a gallon. Because im growing autos which say's on the packet flowering time 28days, and they are a week and half from seed cracking
now. Autos are all about getting a good root zone while in veg ready for flowering'
The autos im using are betty boo fem autos from joint doctor
 

GOLDBERG71

Well-Known Member
Good luck. Glad to help. Just curious why you'd want to use "autos". What happens if you love the plant and want to keep in your library?? I've got some AK47 that pisses me off. Hard to keep from flowering. It's a freaking pain in the ass. But since I'm out of beans I've got to keep it as long as I can because other than than trait it's a pleasure to grow.
 

az2000

Well-Known Member
Since the ph drops as the plant dries our this is why a feed at a higher ph. I expect the ph to have dropped below 6.5 between watering. Therefore my hope is feeding high balances out with the help of the lime.
I think you have that backwards. Doesn't PH rise as the soil dries. That's what I observe with Pro-Mix HP using a $50 soil ph probe.

I'd strongly recommend the OP monitor their runoff as well as invest in a Control Wizard Accurate 8 soil probe.
 

GOLDBERG71

Well-Known Member
I think you have that backwards. Doesn't PH rise as the soil dries. That's what I observe with Pro-Mix HP using a $50 soil ph probe.

I'd strongly recommend the OP monitor their runoff as well as invest in a Control Wizard Accurate 8 soil probe.
Have you ever left a batch of nutes sit for a week after the initial mix and PH correction?? There's only one direction that PH is going and down is that direction. The wet soil is the same thing. But the medium has buffer to slow this down that's why we added line in this case. But that buffer is breaking down from day one. Pulverized lime works faster and loses effectiveness faster as well. Pellets work slow but last longer.
 

GOLDBERG71

Well-Known Member
I've never fought a rising PH. When mixed it's always low. Early veg is much closer to correct and as the strength goes up the PH goes down further. Then more and more PH up needs to be added. From the moment it's corrected by me it will never ever be higher than that reading. It will hold it for a period of time. That period is longer the lower the strength is. Ironically as the strength goes up so does the age and usefulness of the lime goes down. Just like the PH will. Maybe your nutes are different then mine?
 

az2000

Well-Known Member
Get a soil PH probe. Mine shows the medium's ph rising. After I water it might be 5.6 (even though I poured in 6.2). A few hours later it's 5.8. Next day, 6.2. When it's ready to water again it's 6.5.).

What occurs in soil as the water and nutrients is consumed may be significantly different than leaving a nutrient mix in a cup for 2-3 days.
 

GOLDBERG71

Well-Known Member
I've only heard bad things about accurate meters. I've used a blue lab combo meter from the jump. I've looked into the soil PH meters. But from all my reading up on the subject I wouldn't waste money on them. My take away from my reading was they were all basically junk and inaccurate.
 

az2000

Well-Known Member
And if you never let the soil dry out proper in between feedings. Eventually it over powers the lime.
That's because it's holding the soil more acidic. That's one of the problems of overwatering. Not just the risk of root rot, roots that don't get enough oxygen, etc. But, the plant doesn't experience the full range of ph (from, for example, 5.6 to 6.5, it goes from 5.6 to 6.0). It doesn't get better availability of nutrients available at higher ph.

Letting the medium dry could also be the cause of what you see regarding dolomite. Less "work" for the dolomite when the soil is drier and the ph is closer to 7.0. Watering too frequently, never letting the soil dry would have the effect of holding the medium's ph lower (say 5.6- 5.8, making the dolomite work harder.

Get the probe I mentioned. It's extremely useful because runoff ph isn't too reliable. Soil probes aren't usually reliable. I wouldn't get a $5-$20 probe. But the $50-$60 probe is worth it. Wipe the probe's surface before each use. (When the whetting cloth wears out, use 0000 steel wool.). Let it remain in the soil for 10 minutes. The probe is 3/8" diameter. Don't worry about it disturbing roots. Push it slowly in. It seems to benefit the soil by aerating it.
 
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az2000

Well-Known Member
I've only heard bad things about accurate meters. I've used a blue lab combo meter from the jump. I've looked into the soil PH meters. But from all my reading up on the subject I wouldn't waste money on them. My take away from my reading was they were all basically junk and inaccurate.
Ok, but I'm still wondering how you know the medium's ph drops as it dries? Even if a soil meter isn't accurate (say, 5.0 is really 5.4), you're still going to see the direction of the ph.

EDIT: By the way, the "professional?" way to test soil ph is the "NCSU pour-thru method." If you google for that, you'll find the method.

What makes runoff ph unreliable is the amount of time the water remains in the soil before being displaced as runoff is key to interpreting the runoff's ph. If you don't let it sit for an hour (and displace just enough to measure), it becomes a blend of the ph you poured in and the medium's ph.
 

GOLDBERG71

Well-Known Member
I'm not the one having issues. My babies are fine have been fine. I'm just telling the person who asked the question. What and why I do what I do. Like I said my reading up on soil probes leads me to not believe the probe itself and any readings from them. That's just me. Your the only person I've had post a positive from them truthfully. I believe when peat moss breaks down it also lowers the PH. I'm sorry but this is one I'm going to have to agree to disagree on. But I'm no scientist. I just do what I do and read the plants. And no ones complaining about the product. Only rave reviews.
 

GOLDBERG71

Well-Known Member
If I needed my soil checked. I wouldn't be using a meter. I'd take a sample to the local co operative for a real test. Let the college run an accurate one. But like I said. My girls are thriving. The only issue I've had from day one is a little bud rot. Only because I tried to be cheap my first run. I thought I could skip the dehumidifier. Peace out. It seems to me like your trying to prove a point to someone who doesn't have a problem that needs solving.
 

az2000

Well-Known Member
I believe when peat moss breaks down it also lowers the PH. I'm sorry but this is one I'm going to have to agree to disagree on. But I'm no scientist. I just do what I do and read the plants. And no ones complaining about the product. Only rave reviews.
You're right about peat. But, I'm still wondering how you know medium becomes more acidic as it dries when you don't have anything to measure the medium's ph? I mean, you're agreeing to disagree about something you haven't measured.

That's all I'm saying. I use my Control Wizard Accurate 8 (not a cheap $5-$20 probe) every day. I have never seen the soil become more acidic as it dries.

I agree the the meter's reading may not be accurate. It could be off +/-0.2. But, it's not inaccurate in the sense of one time dry soil is 6.6, the next time it's 5.0.
 

GOLDBERG71

Well-Known Member
Besides that we've gotten way the F off topic here. The question is how much lime to add. That doesn't take any kind if meter to answer.
 

az2000

Well-Known Member
It seems to me like your trying to prove a point to someone who doesn't have a problem that needs solving.
I was trying to make sure the OP didn't proceed on false assumptions that his soil is going in the opposite direction than it really is.
 

GOLDBERG71

Well-Known Member
I don't want to argue. You agree peat moss drops ph as it ages. You agree that aging nutes lowers the ph. This isn't multiplication where 2 negatives becomes a positive. If they both go down individually they will go down faster together. The only resistance we have against that is the purpose of this thread. LIME.
 
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