Is run off PPM important?

My runoff is very high compared to my feed water. Is this a problem? They look healthy except for a little bit of yellowing on headband leaves lately.

I’ve experimented on one by overwatering with 600 PPM last 2 days until 500 ML water runs off and that has brought runoff down to 1000. But I don’t know if that’s The best practice.

  • What strain, WW, HEADBAND, blueberry
    Rockwool 6x6 on top of slabs In tray
    In 4th week of flowering.

  • PH of Water, 6.2 feed. runoff 5.2-5.6

  • PPM, 900 feed. Runoff 1400-1700

  • Indoor

  • Light system Spiderfarm 2000 LED at 80%

  • Temps; 70-73 F

  • Humidity; 55- 68

  • Ventilation system; No just fans and open window on warm days.

  • De-humidifier, yes

  • Co2; No

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A soil grow? I can be normal, particularly later in your grow when salts have built up. 1,400 to 1,700 is a good range at that stage in flowering when nutrient demand is at its peak.

You can run PPM back down in a soil grow by feeding only water for a week or so or by performing a flush.

That is fairly normal in a soil grow as @MidwestGuy said.

I grow in Fox Farms Ocean Forest with added perlite and worm castings. I get runoff ppms in the range of 3000 or so at the start of a grow. I don’t really worry about runoff ppm unless I am seeing some sort of problem. As the soil is depleted the runoff ppms will drop unless you start getting salt build up in your soil, again as FixerPower mentioned.

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Not soil. Rockwool

You are doing a media grow. Runoff TDS should be taken at every watering and runoff numbers should be kept to around 1,000 ppm.


So after flushing with ph+ 6.0 plain water a few days my PH rises from low PH 5 range into the 6 range and everything’s great for a couple days then ph starts falling and Runoff PPM started Climbing( nut lockout?) even though im watering with 6.2-6.4 water at 700 PPM until i get 25-30% runoff.
Its like im rinsing out these cubes on a weekly basis which seems not great for the plants cause it drops the PPM to 300-500 for a few days.
Any ideas what’s wrong?

When a plant slows down uptake in flower you will see a drop in PH both caused by salts sitting in media and organic material (roots) breaking down which drives PH down.

The other factors are growing out of VPD range or weak lighting. Both can affect uptake which will affect PH.

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RH has been between 48- 60% last 3 weeks. I believe the spider farmer 2000 light is sufficient because i had to dial back To 75% at one point when it was burning the top leaves 30” away.
Is it ok to continue rinsing this much? Or should I raise the PH of the feed water even higher ?

Late in flower it’s pretty much a waste of time.

This can also be a phosphorus issue: it regulates light management on the leaf surface.

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