Runoff PH significantly lower than initial nutrient solution PH

Hey everyone, hope you’re all doing well.

So every time I water, I adjust the PH of my nutrient solution to 6.5. I am only watering about once a week, maybe every 5-6 days, bc my soil stays pretty moist. So I have been feeding with every watering considering the nutrient solution recommendation says twice a week, but that isn’t possible for me bc I don’t want to overwater. My plant is in week 8 surprisingly and is an auto flower. The reason she is so small is because of early stunted growth that was not able to be caught up with during veg. I water with 1 gallon and get about 15-20% runoff.

My plant is doing great and has never had any nutrient issues that I can tell of. Very lush green color. But every time I test the runoff, it’s like 5.5/5. Even last night, I watered with a PH of 7 and it came out at 5. How is this possible if she looks so healthy?

I’m using FF Happy Frog soil, and am using Big Bloom, Tiger Bloom, tapering off of Grow Big, 1 tsp of Cal/Mag per gallon, and just introduced Beastie Bloomz yesterday. It doesn’t show signs of lock out at all so I’m really confused. Is it a salt build up and I need to flush? Or is the PH in the runoff lower because the plant is actually retaining/absorbing the nutrients, therefore causing the runoff PH to drop? (If that makes sense). Please let me know what you think!

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Runoff pH will creep down and eventually become unmanageable as nutrient salts build up in your soil over time. Recommend following the FF flushing schedule.

I would ditch any type of bloom booster. They are not needed and are more trouble than they are worth. They only worsen the pH problem you are seeing. Bloom boosters also corrupt your PPM readings, as the NPK ratio gets out of whack.


Thank you man. Do I need to get a flushing solution to use or can I just use water? And do I just water until 100% runoff? What PH should I use, 7 bc she’s in flower so a little higher? Am I able to flush the day after watering? And do I use nutes after flushing or what’s the process for that when it comes to giving her nutes again?

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They make the process more efficient and quick.

More than that. Flush until runoff PPM is down to ~300 to 400 PPM. It will take a few gallons.

Straight RO or distilled. If using tap water, pH it to 6.5.


Feed lightly immediately following the flush. let the soil dry out, then resume feedings as necessary to maintain a runoff PPM of 1,000.

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If I’m using RO should I PH it? What about spring water?

You can’t pH RO or distilled. There are no ions in the water for a pH to exist. They have no pH and take on the pH of the medium into which they are introduced.

If the PPM of your spring water is > 100 PPM, then it should be pHed to 6.5.


Okay thank you man! About to flush her now wish us luck

Would it be better to flush her now, an hour before lights go off, or in 7 hours when the lights come back on?

Doesn’t really matter.

Okay thanks brother

The FF feeding schedule I’m using says ppm’s should be around 2,300 right now. Is that too high?

Of course they do. They get paid to sell more nutes, not less.

Yes, it is. I maintain ~1,000 PPM throughout my grows and get plants like this:

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Wow that’s :fire::fire::fire: so if I should wait until it fully dries to give a full feeding, how much should I feed after flushing? And will just distilled water work? I don’t have any money to buy any flushing agents right now

Distilled will work, but it will take more gallons to get PPM down to ~400.

Feed as necessary to maintain a runoff PPM of ~1,000. You should expect to get back to 1,000 over a couple of feedings.

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So when I feed it right after flushing, should I do a full feed or no?

So even using their recommended feedings, should my ppm’s be at 1,000? Are they trying to kill my plant or ? How do they have it listed so high??

I just flushed 3-4 gallons. My ppm’s are right under 1,000 but my PH is still 5.5. Do I keep flushing?

Hey bro, sorry to blow you up. Just an update though, I have literally watered it with 8 gallons I think at this point, and the PH is still 5.5. It will not come up. PPMs are much lower, like 800-900, but no matter what I do the PH won’t come up. I’m watering with a PH of 9 at this point, and when it runs off it’s still 5.5. I don’t know what else I can do at this point. I assumed my runoff was just 5.5 because of the soil, but with what you’re telling me, it should be the same as the water I’m giving it. Please let me know if you know of any solutions.

Also, if I finally do get it to test 6.5, it’s going to be by watering it with a ridiculously high ph water, like 10. And then I feel like once I get it to read 6.5, if I then water it again with correct 6.5 ph, it will for sure just read 5.5 again. What the hell do I do bro? What is going on?

You may need to use Sledgehammer or Florakleen to get the PPMs down to ~300 to 400. Your pH isn’t going to move much until the salts are washed out.

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Hey bro, thanks for all your help. I finally got the PH down to around 6.5. Took about 10+ gallons. The last gallon, I fed, and backed off some of the nutrients. It was sort of confusing bc the ppm of my final runoff was pretty low, I can’t remember like 400-600 or something, and that was with the nutrients I was using to feed. So I don’t really get that. But either way, hopefully we are looking good now.

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