Can You Help Me Figure Out What My EC Pen is Trying to Tell Me

[GreenArmadillo]

Hello one, hello all.
Just recently started using EC/TDS readings, so totally a noob here. I'm using a cheap EC/TDS pen, so there's one or two things i'm trying to figure out.




Firstly, I wanted to calibrate this thing, so I got the bluelab 2.77 EC calibration solution. (=1385 ppm with 500 scale, =1940 ppm with 700 scale)
Now the problem with this cheap-ass pen is that it has no calibration option. No calibration button and no screw to dial in.

So I dip the pen into the calibration solution, and it reads:

3556 uS/cm2 = 3.56 mS/cm2 = 1775 ppm

(Calculating 3.56*500 equals 1780, so therefore this pen uses the 500 scale, which is the NaCl scale)


Now comparing that to the calibration values:

3.56-2.77= +0.79 difference in EC
1775-1385= +390 difference in TDS

So my pen is 0.79 over the EC value it should be reading, and 390 over the TDS value.
Does this mean that if I subtract these values from all future values it will be giving me an accurate reading?

[GreenArmadillo]

Picking up from there, I have some values from when I fed the gals nutes, and from when I gave just good ole water.

Type of Feed	ECin	TDSin	ECout	TDSout	Calculated ECin || Calculated TDSin	Calculated ECout || Calculated TDSout
NutesDaphne	2760 us/cm2	1372 ppm	3555 us/cm2	1783 ppm	1970 us/cm2 || 982 ppm	2765 us/cm2 || 1393 ppm
NutesEsmerelda	2760 us/cm2	1372 ppm	3223 us/cm2	1613 ppm	1970 us/cm2 || 982 ppm	2433 us/cm2 || 1223 ppm
WaterBrittania	?	116 ppm	3560 us/cm2	1765 ppm	? || 116 ppm	2770 us/cm2 || 1375 ppm
(Calibration Liquid)	3556 us/cm2	1775 ppm	-	-	2766 us/cm2 || 1385 ppm	- || -

* Water used was bottled water, which claims 116 ppm as the TDS written on the bottle
* EC calculated by subtracting 790 ms/cm²
* TDS calculated by subtracting 390 ppm



So what does this mean for my girls?
They are in week 5 flower, so do these values make sense?
I am using GO nutes, according to this schedule (more or less, I don't have CalMag so adding epsom salts and an amino calcium feed):




Any and all help is greatly appreciated.
One love homies and homettes.

[growmore]

If you cannot calibrate your pen then the only way you can use it is by figuring out the discrepancy in accuracy as you have done, but in reality the meter is reading the electro conductivity of the solution and any error will be not as a definite number (390 ppm) as you found out but as a % error instead.
3.56-2.77= +0.79 difference in EC
1775-1385= +390 difference in TDS or 22% error
The error is 390 when testing a1385 solution but would not be the same with a different strength solution
At 1000 ppm the error would be 220 ppm and at 2000 ppm the error would be 440 ppm. Or 22 %
Hope that helps

[GreenArmadillo]

That's brilliant information mate. Thank you so much!
I'll certainly keep that in mind. Cheers.

[9fingerleafs]

Yes you should do it for practical purposes but the convertions are not linear. That's why manufacturers recommend calibrating with the same (scale) solution the software is for. So a 500 scale pen is going to read more accurately around 500 Ppms. Same with the 700 scale. What you are going to do substracting values is the same that the calibration screw would do.

[GreenArmadillo]

Okay, that's a good start.

As for my values for the plants themselves. Do they look good, or is something off?
Like especially the fact that my values coming out of the soil are higher than the values going in. Common sense had me thinking that it should be the opposite due to the gals drinking up nutes.
I'm week 5 flower, but i'm growing a sativa, so its quite possible my flowering stage will last anywhere between 10-15 weeks.

[9fingerleafs]

I think those values are super high. Dangerously high. I wouldn't go over 1 EC or 500 ppm during veg and 2 EC or 1000 ppm during heavy feeding flowering

[9fingerleafs]

But hot soil like fox farms usually when first watered with 15 ppm water it comes off around 3000 ppm or 6 EC. I just rinse the soil before planting. Mix with perlite 1/4 and give plain 15ppm water until runoff is less than 1000 ppms. This ensures no burn to the little seedlings but i "waste" what's in the soil. I start adding mainly calmag and some bloom P and K once is flowering. I never give the plants more than 750 ppm or 1.5 when mixing he solution. Just adding water to the soil makes the nutrients in there available so EC it's always going to be higher inside the soil and in funoff

[GreenArmadillo]

Guys, I need your help once more.
I fed the girls their weekly nutes yesterday, and honestly, the run off number were alarming. Check it out:
(PS. Both Alicia and Brittania were transplanted to bigger pots over the past 3 days, with some new fresh fox ocean forest, so that is probably the reason their run-off is spiked way higher than Daphne and Esmerelda, who were both transplanted slightly earlier.

Daphne Transplant: 21/3/17
Esmerelda Transplant: 28/3/17
Brittania Transplant: 31/3/17
Alicia Transplant: 1/4/17


Mixed a 3.5 gallon batch:
pH_in = 6.4
EC_in = 1,388 uS/cm² = 1.39 mS/cm²
TDS_in = 640 ppm

*all values calculated by percentage, as growmore suggested to me above: EC = EC_pen-(EC_pen*22%) and TDS = TDS_pen-(TDS_pen*28%)

	Run-Off pH	ECout	TDSout
Alicia	6.25	4468	2090
Brittania	6.00	error (>9999)	5920
Daphne	6.39	2272	1048
Esmerelda	6.34	7360	3385

Should I be worried? The run-off numbers are for the most part way higher than what 9fingerleafs recommended.
Or were you referring to the numbers going in when you said:
"I wouldn't go over 1 EC or 500 ppm during veg and 2 EC or 1000 ppm during heavy feeding flowering"


Either way, I want to know if i'm doing things right, or something i'm doing is wrong.
Reason i'm asking so persistently is so that I can catch my mistakes early and sort them out before they cause real damage.


Love the support here guys. Thank you all. <3

[9fingerleafs]

That's spot on growmore. Understanding that, one must get to know his soil, plants and water to get the best of them. Learning how they behave under different feeding and watering techniques and doses. I personally think that with a soil like fox farms ( that is very little "dirt" and it's mostly hummus and organic matter with a bunch of beneficial fungi) there's little to be added. We all feed like if we were running hydroponics

[growmore]

9fingerleafs You make a good point about overfeeding when using mix that has a nute value of its own. The only way to use these types of mix is knowing what their inherent nute value is and once you know that, you at least have a good starting point. I grow hydro for the simple reason that with mix you can measure the ppm of your mix but you still have no idea as to what is contributing to that ppm. So I could have a high ppm but have a N deficiency in veg and have a low P and K when flowering.

[GreenArmadillo]

Woah, that's deep.
I see what you guys are saying.

Well, in that respect, is there any form of table or schedule that describes optimal ppm levels at the different stages of a plants life?
I think having benchmark numbers to aim for would make this a lot more doable.
Then as you say, it would be a matter of mixing up your nutes so that they complement the soil, and together give a total ppm run-off that is desirable.
(Instead of blindly following the nute manufacturers schedule)

Really love the details being provided. I feel like i'm becoming so much more knowledgeable.

[GreenArmadillo]

PS. Should I have not fed them nutes that soon after transplanting them to the new FFOF soil? Was that wrong of me?

[growmore]

No you probably should not have. as your ppm reading of the runoff is way to high. Whenever you repot them your first watering should always be with no nutes added until you know what the ppm of the runoff is. With So high nute levels you run a very real chance of damaging the roots and stopping them from taking up water and becoming dehydrated.

[GreenArmadillo]

Damn, my bad. Really glad you told me this!

[9fingerleafs]

Yes. I was referring to the water going in taking in consideration you have a nutrient rich soil (just like I do) so at any point that's the highest I would feed cause there's always going to be new nutrients available from the soil as you provide water and the microbial processes occur on the roots. This is also based on watching numerous professional growers running hydroponics on soiless medium. They follow manufacturers nutrients regimes cause they are made for this kind of growing. We use soil and hydroponic nutrients so we have to be careful cause they're not designed to be used this way. This is a big problem not addressed on the main site (I think) and creates a lot of confusion among new growers. I've flushed happy frog soil to the point of <200 ppms and a week later the runoff is around 1000ppms.

personally I go very easy on the nutes except for calmag cause my water is 10-15ppms and very ph volatile. I'd advise you to water small amounts of low EC water at first without any runoff. The runoff is a must ify ou give nutrients all the time cause you don't want to saturate the medium. But this is not the case if you want to use what's in your medium. I wouldn't worry much about those numbers cause of the soil. Give them low EC Water with lots of runof for now and go easy on the nutes. You have to find what works for you and give the plant the chance to feed from the soil. I'd come to the conclution that in the future I will use coco to have more control over the nutrients

[GreenArmadillo]

Awesome!! With all that was said, it seems I should only be giving water for the rest of this week as well as the next.
So tomorrow was a water-only day anyway, so that's what i'll do. And instead of giving them a nute feed on Saturday, i'll only give them water. (My bottled water is already at pH 6.5 with a small amount of nutrients @ 116ppm so should be light enough). I'll be watering until I get minimal run-off, maybe less than 10%, and test the pH and EC/ppm.
Then next week, Tuesday is a water-only day. Based on my run-off ppm/EC on Tuesday, i'll come back here and post up, and see if I should feed the gals nutes on Saturday 15th of April. That will have given the gals 2 weeks of no nute feedings, since they all have some new FFOF to use up after having been transplanted.

Sound about right?

By the way, what about CalMag. Should I be adding that to my water-only feeds?
I recently received some GO CalMag+ through the mail, so I can finally give the girls some. I had calmag issues during the early flowering phase, so I don't wanna risk getting them again.
And should I be watering until excess run-off during any of these water-only feeds? Kinda like a mini flush?


It might be important for me to add that I have had some leaf issues and symptoms these last two weeks, so it all might be related.
If you have the time and don't mind, could you hop over to my thread about my leaf symptoms, and check out the most recent posts. I think I have some deficiencies/lock out. Something's definitely not right.
I'd really appreciate it.

forum.growweedeasy.com/forum/growing-community/62637-1st-lemme-say-hi-then-lets-diagnose-mid-lower-leaves-sick-blotches-brown-edges/page2

Armadillo love.

[9fingerleafs]

I think you should add a little bit now and then it's always good. About the pot size and plant size and flowering progress in going to take a guess at it.
In my opinion you got there a long flowering sativa that needs more light than it has and due to this slow progress the plant has outgrown the pot which means very little medium left which means it may lack some nutrients. If I where you I'd start some new seedlings and give this plant time to do what it needs to after transplanting to a bigger pot and giving more light (if posible) but mainly try to learn so you don't make the same mistakes. Get some more plants and keep experimenting. Don't put all your eggs in the same basket

[GreenArmadillo]

That's excellent advice man. I'll take it to heart. I appreciate you taking the time.
I've got some auto seeds just waiting to be planted. Unfortunately I don't have any space to plant them now, so waiting on my current grow to end, so as to use the same grow room.

Hmmm, it's interesting that you mention the light levels being a major cause of the problem. No1 has brought that up until now.
I thought 700 watts was good, but obviously as you say, these particular gals are craving some more light.

The way I see it, I have very few options:
1) Keep everything the way it is, but just take the nute feedings a lot more relaxed, and monitor the ppms
2) Order an LED grow light (the con here is that it will take 1 month minimally to arrive here by mail)
3) Buy a proper HPS grow light (the con here is that it will drive up my room temperatures quite a bit. I'm currently averaging 23.5 C during the day. And I live in a hot country where the weather is rapidly going summer-heat-mode. My car was 28 C today when I got in after work, being parked in the sun)
4) Buy an additional T5 light fixture, adding 150 watts to the grow room.


Honestly I wasn't prepared to spend any more money on this grow, as I have spent so much already, but at this point if it really is required then I will definitely do it.

[9fingerleafs]

I'd say option 1 makes more sense. More observation. Sometimes we change thing so fast we cannot see how the plant reacts. I wouldn't spend any more money on light

[alltatup]

GreenArmadillo I think your current experience is so typical of what we go through. We never know when we start out how much it's going to cost to get our grow space to optimal efficiency and environment for our plants. Eventually, we get it set up according to our needs. Now that I've read this thread, I think your girls will prolly bounce back.

[GreenArmadillo]

Tell you what, after reading the responses to this thread I made up my mind a couple of days ago to buy a proper HPS grow light.
So I drive down to the ONLY shop in this country that sells grow lights. (I know, isn't that CRAZY! Only one shope. )
The sad part is that they had sold out all their reflectors. So now i'm waiting for a new shipment to arrive. Fingers crossed they'll have it in tomorrow.

They sell 250 watts, 400 watts, 600 watts and 1000 watts. I'm thinking of buying the 600 watt ballast with reflector and bulb.
They sell the 600 watt ballast in two forms: normal and dimmable. I really want the dimmable, but the price increase is insane!
The normal ballast with reflector and bulb will cost me $300. The dimmable ballast would add $120 to the bill.

I can't wait to get a professional grow light. I feel bad for my girls not having the light they need, and they definitely deserve it.
I wish they sold LEC here, but it's a shame they don't. HPS is the next best thing (unless the grow shop guy shocks me and ends up having ordered LEDs too )

Pray for me and my babies, dear friends.

[GreenArmadillo]

100% my friend!! It's rare for a person to find something to do that they are generally passionate about. This passion makes the money spent well worth it. =)

[9fingerleafs]

it eases me to think how much weed ive already gotten out of that money and how much more ill be able to grow with my setup as is.... not so expensive after all, not like buying expensive weed

[alltatup]

True dat, 9fingerleafs!! I forgot how much I had to spend on a qp!!! Hey, I don't feel so guilty anymore!!!

[GreenArmadillo]

In the meantime, here's my latest readings:

(4/4/17) Water Only pH_in=6.3 EC_in=150 TDS_in=70

	pHout	ECout	TDSout
Alicia	?	?	?
Brittania	6.33	7247	3350
Daphne	7.24	1638	750
Esmerelda	6.07	5782	2694

(9/4/17) Water+CalMag+Molasses pH_in=6.5 EC_in=600 TDS_in=277

	pHout	ECout	TDSout
Alicia	6.07	4155	1937
Brittania	6.24	3120	1562
Daphne	6.20	1763	814
Esmerelda	6.35	4196	1887

Tomorrows a water+molasses day. Should I water with zero run-off? Or minimal run-off? Or 20% run-off?
The ppm numbers seem to be steadily dropping since I stopped adding nutes. Things are going in the right direction, am I right?
I really hope so. Daphne has been dropping a lot of her leaves, all beige, crispy and dry. The rate of leaf loss seems to be getting lower now that i've dropped nutes, but honestly she's at a pretty worrisome stage. Not many leaves left. I'm sorry bae. =/

[9fingerleafs]

Without pics of the plants I can only assume if they're doing great keep those numbers the same. If hey get burned then flush more often of give less nutes. About the runoff I wouldn't worry about that unless you where flushing. Enough to measure ph and ppm it's enough.

[alltatup]

And you should expect leaves to be yellowing and dying at this stage!! Show us some pics!!!!

[GreenArmadillo]

Woah, you blew my mind with that pH analysis of the straight water. I didn't notice that pattern. hmmmmm, as you say, perhaps the soil is out of range. Should I flush with my bottled mineral water, or car battery water (distilled)?

[GreenArmadillo]

My latest readings, to be added to the fray:

(12/4/17) Water+Molasses pH_in=6.97 EC_in=204 TDS_in=89

	pHout	ECout	TDSout
Alicia	6.65	1984	845
Brittania	6.77	1782	826
Daphne	6.70	1779	820
Esmerelda	6.52	3894	1790

(15/4/17) Water+CalMag+Molasses pH_in=6.25 EC_in=575 TDS_in=265

	pHout	ECout	TDSout
Alicia	6.50	2015	938
Brittania	6.72	1462	675
Daphne	6.71	1877	864
Esmerelda	6.61	3116	1440

(18/4/17) Water+Molasses pH_in=6.27 EC_in=215 TDS_in=99

	pHout	ECout	TDSout
Alicia	6.71	2287	1065
Brittania	7.07	627	289
Daphne	7.26	1251	576
Esmerelda	6.77	3471	1588

My stand out personal notes from my grow journal from these last 10 days are as follows:

* The girls seem to be picking up after stopping the nute-heavy feeds. The buds are looking pretty sweet, although not nearly as big or juicy as one would hope, but lovely and plentiful nonetheless.

* I removed Daphnes splint from when I unintentionally supercropped her, and MAN has she made up for it! She's made such a solid joint out of the bent stem.

* The grow shop did not receive any reflectors, and said he won't be receiving the shipment for another month most likely.

* I decided to make due, and added a four-way split CFL set-up as supplemental lighting. 155 watts of 2700K CFLs were added to the middle of the grow room.

* My total grow room wattage now stands at 855 watts.

* I started giving my girls a light supplemental watering (750-1500ml) in between their water+molasses day and the water+CalMag+molasses day.

* I started having a close-up look at the trichromes to see where i'm at. Pictures will be posted in a separate thread.

[9fingerleafs]

Great upgrade

[GreenArmadillo]

Nice one fam. Gotta say, there is something magical about CFL's and their absolute simplicity. <3

[GreenArmadillo]

Here's some pics, from newest to oldest, as requested. =)
(some of these pics are disturbing, i'm sorry)

18/4/17




12/4/17



9/4/17




4/4/17



1/4/17

[alltatup]

Such a beautiful sativa, my brotha!!!

[GreenArmadillo]

oh my days, sooooo many bud sites, haha!
Tall and sexy girls know how to front it. =D

[GreenArmadillo]

Here's the thread I just posted about reading trichomes:

http://forum.growweedeasy.com/forum/growing-community/81782-is-it-just-me-or-is-reading-your-trichomes-really-hard-pre-harvest-help-needed

[CCisme]

We have some of the best spare bathrooms man lolol

[GreenArmadillo]

hahahahaha, oh man.. You got that STRAIGHT UP!! =D