Help me understand Sap Ph Meters and Refractometers

[oxanaca]

My garlic press from bed bath and beyond works well. I use whole leaves. For me the objective is to use this as a guide. Going for real precise numbers is not necessary for me. I look at the values my best plants give me, then look for deviations.JK
I do this around lights on with my coffee. There is more moisture in the leaves at this time. I am using the same time so the numbers stay relevant.

you never mentioned what kind of numbers you were getting off of your plants, would you mind telling? im curious

 

[oxanaca]

So I got the horiba twin a week ago. And the twin ec meter is on the way. I have 52 female plants from seed about 4 feet tall in veg. And am noticing sap ph ranging from 6.6-6.9. And brix from 4 to 9%.

My plants are far from dialed. But I didnt need to use the meters to find that out. Im going to start working with foliars in conjunction with my meters to see what can be done.

The 10in vice grip sap press from pike agricultural is absolutly beautiful. Save the clay extruder for hash pucking its to slow.

Does anyone have experience using soft rock phosphate
Or micronized gypsum or limestone? Used to mineralize coco or soil.

I thought I read that you could foliar feed micronized gypsum (calcium sulfate) in the form of a suspension. And the plant would take it into the leaves as long as the gypsum particles were around 1 micron diameter.

 

[Seamaiden]

I haven't read that, but I'm thinking maybe one of the cats at Sensational Solutions may know (they're the ones who do micronized stuff that I'm somewhat a little familiar with).

 

[oxanaca]

I haven't read that, but I'm thinking maybe one of the cats at Sensational Solutions may know (they're the ones who do micronized stuff that I'm somewhat a little familiar with).

hey if you talk to the good folks at sensational solutions find out for me im interested.

 

[oxanaca]

i got my horiba twin drop EC meter. i also found out i have twin spotted spider mites, damn,
did a little test

i pressed 7 leaves. 3 with moderate infestation 3 looking healthy with no mites. and one with no mites but off a sickly looking plant.
the leaves with the mite damage recorded 10 milli siemens.
the healthy looking leaves were all damn close to 16 mS
the one off the shitty looking plant recorded 19mS
all had a brix of 6 % and a ph of 6.7 except for the shitty plant which read 7.0 ph

i think i need to bump up my mono pottasium phophate to 40ppm P up from 30

 

[joegrower619]

Hey guys I got a buddy from 420 mag forum he sells a high box kit comes with all the foilar sprays drenchs and amendments that u mix with promix HP and worm castings really good product worth a look if ur interested in high brix his trichromes are ridiculous frostiest plant I have ever seen worth a look at his journal I'm saving up for his kit right now prolly purchase next grow it around 70 bucks to ur front door and after seeing his plant it is worth it

 

[leadsled]

@oxanaca Curious as to whether you sampled old leaves or new leaves?
Adding more k from mkp could make the problem with your plants worse. The mites will love it!!

yes mkp aka (mono potassium phosphate) can reduce ph but it also minimizes escape of ammonia.
Which attracts insects. Also good to check you do not have excessive potassium chloride.
That will result in less uptake of nitrogen phosphorus and sulfur. The anions you are possibly in need of.

Hope that helps.

P.S. few references.
http://link.springer.com/article/10.1007/BF01193472#page-1

http://www.amazon.com/Advances-Insect-Physiology-Disease-Vectors-ebook/dp/B00512PW2I

 

[oxanaca]

@oxanaca Curious as to whether you sampled old leaves or new leaves?
Adding more k from mkp could make the problem with your plants worse. The mites will love it!!

yes mkp aka (mono potassium phosphate) can reduce ph but it also minimizes escape of ammonia.
Which attracts insects. Also good to check you do not have excessive potassium chloride.
That will result in less uptake of nitrogen phosphorus and sulfur. The anions you are possibly in need of.

Hope that helps.

P.S. few references.
http://link.springer.com/article/10.1007/BF01193472#page-1

I sample leaves from the middle of the plant. Minus the petriol and midrip.

I dont use potasium chloride, and mkp is the only salt I am aware of that I can use to provide phosphate ions to my plants, besides map (mono ammonium phosphate), and I try to keep my ammonium ion concentration as low as possible. So thats a no go
http://www.amazon.com/Advances-Insect-Physiology-Disease-Vectors-ebook/dp/B00512PW2I

 

[Herb Forester]

Are you working in soil or hydro? Some other options are straight P acid and PeK (MKP with a higher P ratio).

 

[oxanaca]

@oxanaca
Adding more k from mkp could make the problem with your plants worse. The mites will love it!!

yes mkp aka (mono potassium phosphate) can reduce ph but it also minimizes escape of ammonia.

Hope that helps.

P.S. few references.
http://link.springer.com/article/10.1007/BF01193472#page-1

Hey id love to read your references unfortunately I dont have $160 to spend to read it at the moment. Could you copy and paste the part in the springer paper that covers why mkp causes these problems.
http://www.amazon.com/Advances-Insect-Physiology-Disease-Vectors-ebook/dp/B00512PW2I

 

[oxanaca]

My mite problem is under control. I grow exclusively in dripped coco coir. I will switch to chow mix soon though.

 

[oxanaca]

@oxanaca Curious as to whether you sampled old leaves or new leaves?
Adding more k from mkp could make the problem with your plants worse. The mites will love it!!

yes mkp aka (mono potassium phosphate) can reduce ph but it also minimizes escape of ammonia.
Which attracts insects. Also good to check you do not have excessive potassium chloride.
That will result in less uptake of nitrogen phosphorus and sulfur. The anions you are possibly in need of.

Hope that helps.

P.S. few references.
http://link.springer.com/article/10.1007/BF01193472#page-1

Hey dude found some info on wikipedia related to what your talking about related to mkp.

Monopotassium phosphate, MKP, (alsopotassium dihydrogen phosphate, KDP, ormonobasic potassium phosphate), KH2PO4, is a soluble salt of potassium and thedihydrogen phosphate ion which is used as afertilizer, a food additive and a fungicide. It is a source of phosphorus and potassium. It is also a buffering agent. When used in fertilizer mixtures with urea and ammonium phosphates, it minimizes escape of ammonia by keeping the pH at a relatively low level.

This shouldnt effect me seeing how I never use urea or MAP. And even if I did it wouldnt affect my ph as I change this after adding all my salts with sulphuric acid and KOH. Or rather before as I know exactly what to add.

I do think im going to try dipotassium phosphate though as it adds double pottassim and no hydrogen ions so it wont drop my ph. Compared to mkp. Got another 45 pounds to go thru before then though.

if I remember correctly PeK is phosphoric acid stabilized with potassium oxide aka "drip clean"
http://www.amazon.com/Advances-Insect-Physiology-Disease-Vectors-ebook/dp/B00512PW2I