Yellow in middle of fan leaves.

FFOF soil and letting my tap water sit for 24 hours and check soil by putting my finger 2-3" deep before watering. Inside a grow cabinet with mylar and a pretty big bus
Fan blowing on my 3 42w 2700k cfl. My other plant is fine yellowing is very noticable in the middle of my fan leaves on top and and bottom leaves and none on the edge of the leaf. First time grower had these in veg outside for 1 months and.a half now inside growcab 1 week into flowering. No added nutes and pot is a huge rectangle 24" wide.

Here are pics no yellowing on edge of leaf. My other plant is fine.

Looks like cal/mag deficiency maybe but I'm not a pro. So no real help I'm afraid but someone will know. Or look in sick plants section could be relative

Im new as well but Ive read
Magnesium deficiency occurs on the outer edge of the leaf. None have that sympton

Well if ur a month into flowering and u haven't added any nutes maybe she is trying to feed off what's in the leaves. What's her ppms and ph??

Well the Fox Farm soil cotains nutes and it is brand new soil that it just got transplanted too. I don't have a PH meter working on getting that and my other plant recieves the same water and is fine?

Well no pH meter yet working on getting one. But my other plant receives the same water and both were transplanted a week ago into fox farms ocean forest soil

It's hard to say without the ph and ppm. I heard of people saying fox farm soil can burn and cause lock up. If ur other plants are good then I'm no help sorry. I've had issues and it was my ph being off or my ppms to high/low

Fresh soil is really high in ppms. I use happy frog organic natural and when I run RO water through fresh soil the ppms are 3370 and the ph 6.2ish.

Hmm. Yeah I've read that too on Fox Farms soil but usually they are in seedling stages that they get burnt. Also by PPM what does it stand for? Related to a Ph meter? Noob question on that lol.

There's ppm and ec. Here's the difference and meaning. What is the difference between ppm and EC?
Total Dissolved Solids (TDS) is the best measurement of the nutrient concentration of a hydroponic solution. To estimate TDS, one can use a meter that measures the Electric Conductivity (EC) of a solution, and convert the number to TDS in parts per million (ppm). Many meters will do this conversion.

Total dissolved solids (TDS) is typically expressed in parts per million (ppm). It is a measurement of mass and determined by weighing, called a gravimetric analysis. A solution of nutrients dissolved in water at a strength of 700 ppm means that there are 700 milligrams if dissolved solids present for every liter of water. To accurately calculate total dissolved solids (TDS), one would evaporate a measured filtered sample to dryness, and weigh the residue. This type of measurement requires accurate liquid measurement, glassware, a drying oven, and a milligram balance. Example: 50 mL of the 700ppm solution would leave 35 mg of salt at the bottom of a crucible after drying.

Electrical Conductivity (EC) is expressed in siemens per centimeter (s/cm) or milliseimens per centimeter(ms/cm). It can be determined with an inexpensive hand held meter. Nutrient ions have an electrical charge, a whole number, usually a positive or negative 1, 2, or 3. EC is a measurement of all those charges in the solution that conduct electricity. The greater the quantity of nutrient ions in a solution, the more electricity that will be conducted by that solution. A material has a conductance of one siemens if one ampere of electric current can pass through it per volt of electric potential. It is the reciprocal of the ohm, the standard unit of electrical resistance. A siemens is also called a mho (ohm backwards).

For convenience, EC measurements often are converted to TDS units (ppm) by the meter.

The meter cannot directly measure TDS as described above, and instead uses a linear conversion factor to calculate it. Everyone’s nutrient mix is different, so no factor will be exact. The meter uses an approximate conversion factor, because the exact composition of the mix is not known. Conversion factors range from .50 to .72, *depending on the meter manufacturer, which do a good job of approximating a TDS calculation from the meter’s measurement of EC.

* All ppm pens actually measure the value based on EC and then convert the EC value to display the ppm value, having different conversion factors between differing manufacturers is why we have this problem communicating nutrient measurments between one another.

EC is measured in millisiemens per centimeter (ms/cm) or microsiemens per centimeter (us/cm).

One millisiemen = 1000 microsiemens.

EC and CF (Conductivity Factor) are easily converted between each other.
1 ms/cm = 10 CF

"The communication problem"...
So again, the problem is that different ppm pen manufacturers use different conversion factors to calculate the ppm they display. All ppm (TDS, Total Dissolved Solids) pens actually measure in EC or CF and run a conversion program to display the reading in ppm's.

There are three conversion factors which various manufacturers use for displaying ppm's...

USA 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
European 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
Australian 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

For example,
Hanna, Milwaukee 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
Eutech 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
Truncheon 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

Calculating the conversion factor
If your meter allows you to switch between EC and TDS units, your conversion factor can be easily determined by dividing one by the other.

Place the probe in the solution and read TDS in ppm. Change to EC on the meter and read EC in ms/cm.

Conversion factor = ppm / ec.
[Note: ms must be converted to us: One millisiemen = 1000 microsiemens (1.0 ms/cm = 1000.0 us/cm)

According to the chart below:
1.0 ms/cm = 500 ppm (USA Hanna)
1000 us/cm = 500 ppm

Conversion factor = ppm / (ms/cm * 1000)
.50 = 500ppm / (1000us/cm) ]

The answer is your meter's convertion factor and should be a number between 0.50 and 0.72 To improve accuracy, take ec and ppm readings from your res daily for about ten days. Average the conversion factors. The more data points that you use, the closer you will be to finding your true conversion factor.

When reporting your PPM in a thread, please give the conversion factor your meter uses. For example: 550 PPM @0.7 or give the reading in EC, which should be the same meter to meter.

It may also be advisable to give the starting value of your water; there is a huge difference between RO and distilled water with a PPM of approximately 0 and hard tap water of PPM 300 @.5 (notice the conversion factor so others can work out the EC) or well water with a conductance of 2.1 ms/cm.


A note to Organic Growers:
An EC meter has fewer applications for a soil grower because many organic nutrients are not electrically charged or are inert. Things like Superthrive or Fish Emulsion, blood meal, rock phosphate or green sand cannot be measured with a meter reliably when they are applied or in runoff. Meters can only measure electrically charged salts in solution.

"The solution"...
When reporting your PPM in a thread please give the conversion factor your meter uses for example 550 PPM @.7 or give the reading in EC (the EC shoul d be the same meter to meter).

Very good information ! Thanks. I obviously need to buy more tools to help this grow be successful little by little

Ur welcome glad I can help. I'm learning all this too. I have a blue lab ppm/ec meter that's was around $100 and it works great. I have a Hanna checker ph meter I broke now I'm using ph strips from home depot. Once I can afford I wanna get a blue lab ph meter it's like $120 some places is cheaper. They are great tools to have and it makes things easier.