Please help with ec/ppm runoff questions

Hello everyone, I am new to this forum. I’ve only been growing on and off a couple of years. I have some questions please. Regarding EC/PPM, input and runoff.

Currently I have one plant- Godfather OG Auto. I bought photo seeds from North Atlantic Seed Company but it turned out to be auto.

Tent is vivosun 2’3’. Led lights- SF 2000. Coco loco medium. 5 gallon fabric pot. FF nutrients and cal mag. I don’t follow the ff schedule (I’ve noticed it’s too much) so I use half what they suggest. Watering with spring water (my tap water is well water and hard). Ph down to adjust ph to 5.8 to 6.2. Temp is 70 rh is is 50. 3rd week flowering noticed leaves have brown tips and don’t look great to me. Bought the apera ph/ec/ppm combo meter and tested my runoff today- ec was 6.2 and ppm was 3021 (on the 500 scale-another thing that confuses me with all the numbers I’ve been reading). The water going in was ec 1.1 (only added cal mag and ph down) and ppm 521, ph was 6.2.

I’ve been reading all day and feel more confused. I’ve had success growing in the past however I still need to practice my drying and curing techniques because I seem to ruin it all. The hay smell never goes away but that a whole other topic hehe. I just really want to get this process right, I truly enjoy growing. Please tell me what I should do. Should I flush, should I use an additive to flush with, what should my readings be according to my meters scale. I’d appreciate any input, thank you!

Plant doesn’t look bad but showing some N toxicity. This can affect flower production adversely.

EC (Electrical conductivity) is the base measurement that gets converted into PPM: both 500 and 700 scale. 500 scale is called the NaCl scale (salt) and the 700 scale is PCl (potassium salt). We use 500 scale here. EC of 1.0 equals 500 ppm NaCl scale.

Soil buffers salts differently so can get away with somewhat higher levels in it. That said; the way to utilize your meter effectively is to measure runoff TDS and either feed or water only depending on the amount. For example: measure 1,000 ppm (EC 2.0) in runoff. That tells you to feed. When runoff hits, say, 2,000 ppm (EC 4.0) then water only until TDS drops.

In coco I would also follow those numbers.

Your meter requires maintenance to keep it from failing. You absolutely need calibration and storage solution. Never store PH probe dry and never use anything but 4.01 calibration solution or actual storage solution. Bluelab makes a kit that does a good job.

Your light is marginal: good for one plant FYI.

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Thank you so much! So I’ll just water with ph adjustments (no nuts) until runoff is back to normal. No need to flush? I appreciate the info that makes more sense to me now :grin:

This was a thing a couple of years ago but makes more sense and less work to simply modify watering/feeding until everything is back. It will seesaw back and forth but the plant should handle it fine. If you were doing hydro it would be a different deal but coco will provide some buffer.

FFOF often sees TDS’s in the 4,000 to 5,000 ppm range for example.

You are also doing well to keep the TDS low as Autos tend to burn more easily. Upping your light will increase uptake and help with denser flower. Autos often trend toward looser flower and lower light intensity doesn’t help. You want around 200 watts of quality LED’s to properly flower out one plant. I’m currently running 5 plants under 4 homemade fixtures at 200 watts/panel. This is where I’m at now:

I’ll likely yield 12 zips for the right 3 each and 8 or so for the little ones on the left. Crystal, Gold Leaf, Afghan, Sour Diesel, Durban Poison. All photos, Jack’s 3-2-1 in Autopots.


That is beautiful! I would want to stay in there forever :blush: thank you for sharing, that’s a whole other level…

After watering with 2 gallons and no nutes today my runoff is down to 2.2 now. I am guessing I should resume feeding with nutes tomorrow? This is by far the most fun hobby I’ve ever taken on, what a great ride! Thanks again Myfriendis410!

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Coco Loco is not Coco Coir and should be treated as soil as far as pH. Been down this road so many times. I use all 3 from FF. Happy, Ocean and Loco. I would stay between 6.2 and 6.5 using Coco Loco.


oh wow I just read the ingredients and I feel like such an idiot…I’ve never used coco loco before just straight up coco with perlite but this one has other stuff in it…should have read more thoroughly…thank you for clarifying this changes things…

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Yup, and due to conflicting info on the web, I called them directly and asked and it is not an exact % per bag, they vary. The rep I spoke with said no bag will have less than 30% coco fiber and no bag will have more than 50%. So there is quite a swing there. I got me some pics too

Dont. It happens. Glad I happened to be here!


Good catch on the Coco Loco: I missed that.

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