Understanding Run Off Numbers vs Feed Water Numbers

I’m growing in soil with perlite added in a 7 gallon pot with extra holes drilled all over and on the bottom. I’m using GH 3 part nutrient solution mixed in rainwater as listed on the bottle. Plant sits on drip through lift which sits in a collector pan with a pull out tray collecting the water. Yesterday I poured 1 gallon of feed water in and 3.5 cups came out. INPUT = PPM 1100, EC 2.0, PH 5.23. I put in lower PH level feed because my SONKAR Soil PH meter showed my soil was just between 6.5 and 7.0 and I wanted to get it to drop. OUTPUT = PPM 420, EC .8, PH 4.73 Guessing my soil meter is off?
This morning thinking those output numbers were to low, I fed again only 1/2 gallon of feed water getting 1/4 gallon back out. Feed water INPUT = PPM 1020, EC 2.0, PH 6.02 OUTPUT = PPM 390, EC .8, PH 4.64.
This is Orange Bud a week into flower. Are these numbers wrong, or am I confused on what the out out numbers should be? Thank you for any help. This is my first grow. Mark

What meter are you using?

Welcome to the forum.

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Thanks for the welcome, The in soil tester I use is a SONKAR 3 in 1 Light, PH, Moisture meter. I use APERA PH60 and a Bluelab Conductivity Pen for in water testing. I did calibrate the PH60 recently. Here is what she looks like.



Ignore what you see from this meter. The pronged meters are inaccurate and worthless. Rely on your Apera meter.

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Thank you, that was the plan. I didn’t think that two prong $10 thing would be very accurate, but I was hoping for something close, oh well. Any suggestions on what I need to do next? Thanks again!

Adjust pH going in to maintain runoff pH between 6.3 and 6.8.

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Still not getting the numbers up on the run off. Is this plant taking in this much, or am I misunderstanding what should go in vs what comes out?
This morning I fed 1/2 gal with PPM 1440, EC 2.9, PH 6.0. Four cups came out the bottom with PPM 560, EC 1.1, PH 4.90
I waited an hour or so, then fed again 1/2 gal with PPM 1460, EC 2.9, PH 6.25. Six cups came out the bottom with PPM 580, EC 1.2, PH 4.83
After lunch fed another 1/2 gal with PPM 1520 EC 3.0, PH 6.5. Seven cups came out the bottom with PPM 690, EC 1.4, PH 4.70.
I know the PH should be 6 or 6.5 coming out the bottom, so should I be putting in a higher PH feed, or could it flip on me and go too far the other way?

Feed at a higher pH until you achieve a runoff pH between 6.3 and 6.5.

Feed as necessary to achieve a runoff PPM of ~1,000.

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Thats a pretty low pH. You might want to look into flushing it to bring it back up to a cozy 6.5
I know if it was my plant i would be pulling my hair out. I had a few that were 7.9 and had to flush.

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This is what she looks like tonight. I just ran 1/2 gallon of rainwater PH at 8.0 through it and got PH 4.98 on the run off. Lights out now, so back on it in 12 hrs.

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6 days later…


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Wow! Big difference… looks like you got it together. Sometimes you just have to fush the soil out real good. You actually could’ve taken it straight to the sink to flush it out with straight tap water to get the pH up from 4.7 to 6.5 and once the run off pH is in a normal zone you can feed high PPM on the last watering…
Are you about 2 weeks into flower in that pic?

Om so im reading this tread .and my question is when yous say feed with higher PH is that with nutrients or just or without…more like a flush with PH water

The picture is 2.5 weeks in flower, She’ll be 3 weeks in flower on Sunday. She’s pretty wrapped up in a SCROG net otherwise I might have taken her out to the deep sink next to the tent. Thanks for the tip, I’ll remember it for the next run if needed.

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If your EC/PPM numbers are up, then PH’d water only. But if all numbers are low, Feed (water with nutrients) with the correct PH level.

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We are at the same stage. This is my first cannabis grow and they are starting the 4th week of flower yesterday.

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She’s looking good 4 weeks in flower. I just added a second net to help with support. Latest output numbers were PPM 1010, EC 2.0, PH 6.62

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Just finished week 5 of flower. 3 more weeks to go, more or less.

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Thats looking beautiful! You did great!

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