Indoor grow with Fox farms coco loco.
8 Autoflowers in 5 gallon fabric pots. Using two 700 watt LED lights. I’m having an issue of leafs turning light green and dying. Only in week 7 of the grow and I’m worried that my blue land ph pen may be off and giving wrong ph reading and I’m getting lock out do to the wrong PH? The pen is two years old and still calibrates fine. But it does take some time for the reading to level out when I test my nutes. I use RO water and Lotis nutrients also. Anyone have experience with blue labs ph pens going bad after a couple years?
Mine is older and fine. Once calibrated, you can check it any time against the 7.0 to see if it holds true. It always takes around 1 min to level for accuracy. @low has had it go bad on him. The only one that I can think of on here.
The pink splotches and decay, to me, indicate Fe excess. Weird cause you’re using RO that has none. I think you need a support ticket to dig into this more.
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COPY/PASTE the below list into your forum post.
Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so; Or post
NA (non applicable)
-What strain, Seed bank, or bag seed (photo or auto)
-All Nutrient used
-Age of plant
-If on 12/12 then, Number of days actual flowering and date of flip
-Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
-Vessels: Type and capacity of container (fabric, plastic, etc)
-PH and TDS of Water, Solution, runoff (if Applicable)
-PPM/TDS or EC of nutrient solution if applicable
-Method used to measure PH and TDS
-Indoor or Outdoor if indoor, size of grow space
-Light system List brand and wattage/spectrum
-Actual wattage draw of lights
-Current Light Schedule
-Temps; Day, Night
-Humidity; Day, Night
-Ventilation system; Yes, No, Size
-AC, Humidifier, De-humidifier,
-Co2: Yes, No
If growing Hydro some additional questions:
-DWC? RDWC? Autopots? Ebb and Flow? Other?
-Distance of liquid below net pot (DWC)
-Temperature of reservoir
-TDS of nutrient solution
-Amount of air to solution
Got me to thinking, @Budbrother (I won’t be doing that again! 
).
I installed an ro system for watering my gals, and eventually stopped using it. I couldn’t seem to get my Ph and ppm in sync.
Just found this:
“Reverse osmosis (RO) water can potentially lead to excess iron in plants if the source water contains high levels of iron. While RO systems are designed to filter out many impurities, they may not completely eliminate all iron, especially if the concentration is significant.
Symptoms of Iron Toxicity
Excess iron in plants can cause several toxicity symptoms, including:
Stunted growth
Leaf discoloration (yellowing or bronzing)
Reduced overall plant health”.
https://www.sciencedirect.com/science/article/abs/pii/S0176161724000889
Thank you the reply. I do have high iron in my water and have a softener system that helps keep my iron low. But. Had ran out of softener salt and now think they may have been my issue. I’ll have to keep and eye on it.
Thank you for the reply.
@Fields , best of luck. We’re all on a journey 
The one thing about growing anything is that there is no such thing as growing everything… without a little help.
Some folks here have met my beloved Nancy 
Using softened water could be harmful for your plants too. But I would also think a properly working ro system would strip this to be acceptable.
I agree, check the meter against a known source like calibration fluid. Assuming you have made sure your calibration fluid hasn’t been contaminated or diluted, this should confirm or elimate issue with the ph tester.
I would also like to check you have reasonable ppm/ec to accurately test your solution. If it’s not 150ppm or higher i don’t think your tester will display a proper ph.
I would add that checking both sides of the scale is important. Usually unnecessary, but I calibrate with both 7% and 4% solutions. Make sure your storage solution is fresh. They have an expiration date (I learned this the expensive way).
That meter doesn’t calibrate without using both. I still use my expired bottles without any issues. As long as you don’t contaminate them. Did have some issues calibrating during winter when they don’t read exactly 7.0 or 4.0 cause of temp. But had that problem before they expired also.
I used the RO Buddy and their pump system had a well that was saturated with iron. The RO Buddy worked well. Checking with a ppm pen can let you know when the filters aren’t working…RO should be very low ppm…add a “Di” filter as well…the ppm should be “0”.
Great post man!!! Thanks.