I'm prepping my Coco/perlite for my next indoor auto grow but can't get the run-off ph lower than about 6.5. I'm flushing with ph5.5 over & over but doesn't seem to make any difference. Am I missing something or am I doing something wrong?
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Run-off ph problem?
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Take this for what it is worth, google AI says that 6.5 is actually a good number. If you have that steady reading while doing a flush that means the coco has reset itself to a stable starting point. I don't know if that is entirely accurate or not, but it sounds logical.
Do you have a way to measure the EC? google AI and another coco specific web site also say that EC is a better measurement because it measures the salt buildup in the runoff. That is accurate.
I grow in a 50/50 blend of coco/perlite. When I wash my used coco I use plain PH'd tap water and then a Ph'd solution of water/cal-mag, but haven't ever measured the PH in the runoff. I usually let the runoff drain away entirely simply because of the volume of water.Last edited by golfnrl; 09-30-2025, 11:55 AM.Growing Autos and Photos, Gorilla Grow tents, AC Infinity fans, exhaust, filter, humidifier, and controller, HLG Lamps, 50/50 Coco/Perlite, Autopot system, BlueLab PH Controller, CX Horticulture nutrients
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Thanks for the reply. I'm making a point on this grow of following only ONE SITE for advice and assistance which is GWE. The info says to aim for 5.5 - 6.5 ph for coco and I'm assuming that is measured at run-off. I don't have an EC meter but use a TDS instead. Rainwater+ lemon juice going in sits at about 35 and coming out the bottom of the pot is about 130. I'm kind of wondering just WHY I don't seem to be able to get the run-off ph any lower.
Reading the GWE tutorial on ph & water it implies that the only place it's measured is in the added water, no mention of run-off.
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I am seeing the same as you on GWE. Everything I know about growing weed I have learned here. Either from GWE or the members of this forum or both. I do look at coco for cannabis when I have something that cannot be easily answered at GWE. I think TDS can tell you the same thing as EC just stated differently. My guess is the 6.5 PH with clear runoff is OK.
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That a great tip for everyone starting out 2ShedsJackson. Pick one source of quality grow info to follow and stick with that one. There’s so much info available I see people all over the place making it much harder to figure out when your learning m
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Don't worry about pH runoff. I never measure it anymore and it is not representative of the pH at the roots which is what matters.
Coco has a pH of 6. Start feeding at that input.
I hope your flushing with a calmag buff..coco needs thatFlower Room: 11' x 7' x 7.5'H, 480w AC, 13gal/day dehumidifier, 1.5gal ultrasonic humidifier, 60gal (27gal usable) nute tank, 16" pedestal fan & 18" wall fan. Lighting and climate automated. Hand watering.
Veg Cupboards: Two 4x2x6H cupboards. SF2000 Evo in one SF7000 in other. Climate controlled and automated. Hand watering
Aeroponics Low Pressure Bucket: 20W LED. 5 clones & 20W LED 11 clones
Lights: Mars Hydro FC-E1200W, SF-7000, SF-2000 evo in flower room.
Medium: Coco/perlite, 7.2gal pots, no drains
Current Grow: 5 x Photos Franklin's Orange Zkittles x Sour Diesel in flower room, 3 Franklin's White Widow x Sour Diesel Clones, 13 x Orange ZkittleZ x Sour Diesel clones in Aeroponics buckets x 2.
Last Grow: A mix
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