Hi guys and gals, first post. I have a little spot on one of my leaves, what could it be?

[SweetSkunk]

What are you growing in, and exactly how hard is the water? Do you have a pH and hopefully a TDS or EC meter to check hardness? Mineral rich water will become an issue if it's bad enough,...cumulative amounts of CaCO3, usually not in available forms will start to drive pH up, interfere with nute uptake,... the spots are odd looking, not the usual color for Ca defc.,... the neem spraying, too muc too often can get the leaves touchy for reactions,...
If you're growing in soil, or peat based soilless, even coco, checking in-pot pH is critical,... As for ROor Di water, you can blend it with your dechlorinated tap water, but you'll need that EC/TDS meter to do it,..... BTW, how close is that light, and what's the T and RH% in there?

I'm growing in biobizz light mix. The water, although untested as I have no pH or EC checking equipment (but will make an investment soon), is 273 mg/l CaCO₃ according to my water board.

I don't think the neem is too much of an issue as I don't over do it and none of the other plants have an issue.

I have 3 x 600w cool tubes connected to a thermostat so if the temps do peak above 30C they will shut of and cool for a few minutes. The temps rang from 17C at min and 30C max. The lights are 15-19 inches from canopy and the RH IS 30%

 

[namvet25]

Hi AFN,

I previously posted here about a sick plant. It was suggested it could be a burn mark which I've ruled out or a PH problem.

The problem is spreading so I need some advice.

I am running:

• 12 plants in 15L (3 gal) pots
• 3 X 600 HP's
• Light mix
• Tangs easy feeding schedule

So my next step would be to start checking the PH, which I've only ever done once in a failed Coco run.

How would I go about this? I would obviously need a pH probe and pH water tester. How would I go about calculating pH up or down with my results from measuring the soil and nuted water?

Let's say, just as an example, my soil is pH 6 and my water+nutes was 7.5. what calculations would I do to determine the required amount of pH up or down? And what pH up or down should I use?

I seem to remember in the Coco run that it was not advised to use either the up or down (not sure which one) as it was made up of one of the NPK elements.

Any advice on the pH or what's wrong with my plant would be great!

Many thanks and sorry for the long post

First thing you need is a good PH tester and make sure your intake water is near 6.5.Always test after you add nutes.The best ph up and down is made by General hydroponics and this is available at any gro shop or Amazon.You should also be using cal/mag to prevent other problems.

 

[Rev. Green Genes]

-- Calculation ->>> If your runoff pH is higher than your starting (water) pH, use this equation to determine your soil pH:*
Soil pH = Runoff pH + Difference

--- If your runoff pH is lower than your starting pH, us this equation:
Soil pH = Runoff pH - Difference.

For example, say your the starting pH of your solution before it goes in is 6.5 and the pH of your runoff is 7.0. The difference is +0.5, so using the above equation:
Soil pH = 7.0 + 0.5*
Soil pH = 7.5

If your starting pH is 6.5 and your runoff is 6.0, your difference is -0.5 and using the above equation:
Soil pH = 6.0 - 0.5
Soil pH = 5.5

 

[Waira]

whoa! -- that's seriously hard water,... that needs to change ASAP, or the pH will become alkaline as well, and start more problems,.... what are you feeding, and how much/often?
temp and RH% is not good either,... how far away are the lights?

**edit** I merged the threads, no need for multiples,... noted on the feeds/schedule,... you need the right gear mate, no way around it....

 

[SweetSkunk]

whoa! -- that's seriously hard water,... that needs to change ASAP, or the pH will become alkaline as well, and start more problems,.... what are you feeding, and how much/often?
temp and RH% is not good either,... how far away are the lights?

**edit** I merged the threads, no need for multiples,... noted on the feeds/schedule,... you need the right gear mate, no way around it....

Yer we get really hard water here!
I have done multiple grows with this water, however they have all been under someone else's "rule" and done their way, which was awful (no nutes, replanting autos, 40+ plants in 10L pots etc etc)

So now I run:

• 12 x 15L smart pots
• Bio Bizz light mix
• 3 x 600 hps 5 inch cool tubes
• I follow Tang's easy feeding schedule which uses sensi advanced nutrients A and B as well as carboload and overdrive.

The original issue, with he yellow/brown spots on the leaves doesn't seem to be affecting new growth which is a good sign?

Temps I thought were good, It never goes above 30C with lights on and is usually 26.5-30C lights on. Lights out it goes no lower than 17C ( I have a little greenhouse heater in there on a thermostat)
RH i have always had a problem with and nothing I have done seems to help. From hanging wet towels to an actually humidifier. Although this only seems to be a problem as seedlings when the RH is better to be higher?

I do plan on getting a reverse osmosis system but not till after this run. I guess that will resolve all the issues Im having?

Thanks for taking your time to post! Much appreciated!
Regards,
SS

Edit:
The lights are 15-19 inches away from the canopy

 

[Waira]

... lights are too close, should be about 24" t this stage,....

.... new growth being OK isn't a indicator that the problem is solved; it depends on what nute' element defc.'s are in play...the plant can scavenge certain mobile (within the plant) nutes from older established growth, but not all,.. some are poorly mobile (Ca), others are immobile (most of the micronute's) meaning once locked into the tissue, they can't be translocated to support newer growth
here's the deal: actual in-pot pH is critical to know because it determines in part what the next step is... if the pH is off, it needs to be corrected first, or nute(s) will remian locked out, rendered unabsorbable,.... if you feed more, matters may worsen!
So in your case, I suspect off-pH in the pot, and maybe another influencing factor, how much ionic load is in the soil,.. too much build-up may not burn right away depending on what's in there, but it can start to interfere with uptake of other nute ions,... With no pH probe, you have to rely on the dubious run-off method; we have an improved one here in the colored "sticky note" section above this one,... that's where Rev got that pH calculation guide probably,... AN nutes are "self buffering" only when in solution, not after they go into the pot,.. and that hard water is totally overwhelming it buffering capacity anyway,.... You'll need to get low ppm water to do it right, and to flsuh if necessary,... those self-fill water machines usually produce great water for this, much cheaper too!,....

 

[SweetSkunk]

... lights are too close, should be about 24" t this stage,....

.... new growth being OK isn't a indicator that the problem is solved; it depends on what nute' element defc.'s are in play...the plant can scavenge certain mobile (within the plant) nutes from older established growth, but not all,.. some are poorly mobile (Ca), others are immobile (most of the micronute's) meaning once locked into the tissue, they can't be translocated to support newer growth
here's the deal: actual in-pot pH is critical to know because it determines in part what the next step is... if the pH is off, it needs to be corrected first, or nute(s) will remian locked out, rendered unabsorbable,.... if you feed more, matters may worsen!
So in your case, I suspect off-pH in the pot, and maybe another influencing factor, how much ionic load is in the soil,.. too much build-up may not burn right away depending on what's in there, but it can start to interfere with uptake of other nute ions,... With no pH probe, you have to rely on the dubious run-off method; we have an improved one here in the colored "sticky note" section above this one,... that's where Rev got that pH calculation guide probably,... AN nutes are "self buffering" only when in solution, not after they go into the pot,.. and that hard water is totally overwhelming it buffering capacity anyway,.... You'll need to get low ppm water to do it right, and to flsuh if necessary,... those self-fill water machines usually produce great water for this, much cheaper too!,....

I'm going to invest in a soil probe. Can you recommend a reasonably priced pH tester for water? I'm going to get an accurate 8 for the soil.

In terms of water, what water filling machines do you mean? Surely i need RO to ensure its "pure"? I'm in contact with a company at the moment; hoping that i can adapt their system to allow me to fill my 200L water butt.

Cheers for your help !
SS

 

[Mr Green Fingers]

I'm going to invest in a soil probe. Can you recommend a reasonably priced pH tester for water? I'm going to get an accurate 8 for the soil.

In terms of water, what water filling machines do you mean? Surely i need RO to ensure its "pure"? I'm in contact with a company at the moment; hoping that i can adapt their system to allow me to fill my 200L water butt.

Cheers for your help !
SS

Hi Mate, I use an ETI PH Pal Plus for testing the PH of my water and solution, really good meter and only needs to be callobrated to 7 so only need to but the 7 buffer, you will need to callobrate this meter weekly to keep it accurate and also I store mine in storage solution when not in use but I think you need to do this with all meters, hope this helps!

 

[SweetSkunk]

Hi Mate, I use an ETI PH Pal Plus for testing the PH of my water and solution, really good meter and only needs to be callobrated to 7 so only need to but the 7 buffer, you will need to callobrate this meter weekly to keep it accurate and also I store mine in storage solution when not in use but I think you need to do this with all meters, hope this helps!

Cheers mate I'll be getting one with the accurate 8.

 

[Mr Green Fingers]

Cheers mate I'll be getting one with the accurate 8.

No worries bro, if your in UK this is by far the cheapest I found it
http://www.britelite-hydroponics-uk...ge=product_info&cPath=113_73&products_id=1132