Soil runoff @ pH 5.0!? How did this happen so fast?

OK, well I found out what the cause of my problems were. I posted about some curling/canoeing leaves and some brown/rust spots I was starting to see on a few plants. I decided to flush and the initial runoff was pH 5.0! I was using distilled water to flush (pH 8.0) and then switched to pH'd tap water (pH 7.1).

Anyway, I flushed the 5 gal container with about 4-5 gal. I ran out of time in the light cycle or I would've flushed more. But I only got the pH of the soil runoff up to about 5.4 after the flush. So, I'll probably need to flush again when it dries out.

So, how did my soil get this acidic so fast? I'm using Fox Farms Ocean Forest cut with a small amount of perlite (10-20%). I also added some powdered agricultural/dolomite lime although the dose was negligible. I used like 5-6 tablespoons for an entire bag of FFOF, so not very much. This plant is only 5 weeks old (from clone). It spent it's first 4 weeks in a 1-2gal container and was just transferred 1 week ago into a 5 gal container with fresh FFOF. So, how did it get this acidic this fast!? I water with pH'd water usually around 6.8. I did initially water with lower pH (maybe 6.0-6.3), but that was only for a week awhile back. I've only fed nutes once (Humboldt Nutrients) and the solution was pH 7.0 and only like 300-400ppm.

I think FFOF just sucks... Am I going to be battling low pH now throughout the remainder of the flowering cycle? What should I do to combat it? Should I water with like pH 7.0 water? Higher?

Peace:rastasmoke:

Well, as I watered some other plants today I noticed that the other plants are also having low pH runoff. One of the White Widows was at 5.1, but it's not showing any of the canoeing or brown spots. The Sour Diesel and the Headband are the ones that are affected by this low pH. I'm thinking nutrient burn also contributed... so it probably wasn't only pH.

Take a breath. :)

Did you check the ppm of the runoff?

Fresh FFOF _will_ give you very low runoff pH. If you've only been in the 5 gallon for a week, chasing pH runoff is going to result in disaster.

I nearly freaked the first time I checked, it was also in the area of 5 out (in @ 7). Seemed impossible, so I did a soil test. Soil tests pegged it at 6.5. The FFOF is buffered pretty well, adding a little additional lime should have helped to stabilize it even more.

I honestly doubt there is a real soil pH problem, other than variation of the water going in. Keep it ~6.8 with the FFOF.

Don't panic too much if they start looking worse, before looking better. Slugging them hard with that 8.0 stuff may piss 'em off. :(

I doubt very seriously it was the Fox Farms Ocean Forest. Why did you add dolomite and perlite? That stuff is perfectly balanced.

Most references show PH of most distilled water to be on the acidic side, so I question the reading of 8.0 or that the water is distilled.

You, by adding stuff to the soil, messed with/flushed out the buffers they put in. Dang it, I cannot get it through to you that you are killing with kindness.:hippy:

Seriously, man I just use ffof and RO water, but PH stays in the 6-7 range on the water. I don't water enough to get runoff until late in the flower cycle. The only fertilizer I recommend is a TINY bit of 16-16-16 slow release at the beginning of the flower cycle. (I am experimenting still, but best results are as stated.)

FFOF has enough good stuff in it to get 6 weeks of awesome growth before needing to supplement nutes....if you don't wash them all out.

Just transplant them to fresh soil. My plants in 3 gallon containers, under a 1000, 3-4' tall use about a quart of water a day in flower. If I over water and flush out the buffers and salts, then everything I put in has to be in balance.

By not watering so much it does not wash out the pots, and by not adding more salts (RO water controls that, but it is not distilled), or fertilizers (salts) the balance stays the same, the plant has a great root environment, and the plant stays healthy. The most I have seen as far as nute disorder on FFOF is K, but that could be because of the 16-16-16.

Want to test it? Pick two plants at seedling stage that are similar in growth and size. Just one treat the way I suggest. Do all the fun stuff to the others. This will be a boring plant, until about week 4 in flower.

This actually is what I consider advanced growing, because you have to chill and let them stay pretty dry. Lots of sips of water so it soaks in, not runs through.

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Originally Posted by EvilCartman

Take a breath. :)

Did you check the ppm of the runoff?

Fresh FFOF _will_ give you very low runoff pH. If you've only been in the 5 gallon for a week, chasing pH runoff is going to result in disaster.

I nearly freaked the first time I checked, it was also in the area of 5 out (in @ 7). Seemed impossible, so I did a soil test. Soil tests pegged it at 6.5. The FFOF is buffered pretty well, adding a little additional lime should have helped to stabilize it even more.

I honestly doubt there is a real soil pH problem, other than variation of the water going in. Keep it ~6.8 with the FFOF.

Don't panic too much if they start looking worse, before looking better. Slugging them hard with that 8.0 stuff may piss 'em off. :(

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Yeah, I've noticed this about the FFOF. Almost all of my plants have a runoff in the mid-5's pH-wise. But all the older, larger plants look great.
I don't know exactly what was causing my problems but I think it was probably over-fertilized. The plants that were showing these symptoms were 1 week younger than the large plants (which loved the nutrients)... but these younger plants were a lot smaller and probably couldn't take it.

Thanks for the reassurance. I'm glad I didn't do a serious flush. I flushed the other younger plants only about 2-3 gallons through a 5-gallon. So, hopefully I should have some buffers and nutrients remaining in there.

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Originally Posted by WashougalWonder

I doubt very seriously it was the Fox Farms Ocean Forest. Why did you add dolomite and perlite? That stuff is perfectly balanced.

Most references show PH of most distilled water to be on the acidic side, so I question the reading of 8.0 or that the water is distilled.

You, by adding stuff to the soil, messed with/flushed out the buffers they put in. Dang it, I cannot get it through to you that you are killing with kindness.:hippy:

Seriously, man I just use ffof and RO water, but PH stays in the 6-7 range on the water. I don't water enough to get runoff until late in the flower cycle. The only fertilizer I recommend is a TINY bit of 16-16-16 slow release at the beginning of the flower cycle. (I am experimenting still, but best results are as stated.)

FFOF has enough good stuff in it to get 6 weeks of awesome growth before needing to supplement nutes....if you don't wash them all out.

Just transplant them to fresh soil. My plants in 3 gallon containers, under a 1000, 3-4' tall use about a quart of water a day in flower. If I over water and flush out the buffers and salts, then everything I put in has to be in balance.

By not watering so much it does not wash out the pots, and by not adding more salts (RO water controls that, but it is not distilled), or fertilizers (salts) the balance stays the same, the plant has a great root environment, and the plant stays healthy. The most I have seen as far as nute disorder on FFOF is K, but that could be because of the 16-16-16.

Want to test it? Pick two plants at seedling stage that are similar in growth and size. Just one treat the way I suggest. Do all the fun stuff to the others. This will be a boring plant, until about week 4 in flower.

This actually is what I consider advanced growing, because you have to chill and let them stay pretty dry. Lots of sips of water so it soaks in, not runs through.

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I question that distilled water too... got it from the supermarket. But my pH meter was calibrated and it's a good pH meter.

My plants actually look really good. I'm not killing them with kindness. I never water like this. I usually water until I see a few drops come out the bottom and I do it slowly, so that's all that comes out! I let my plants dry out pretty well too.

The majority of my plants are doing excellent, but these fuckin' Sour Diesels are driving me nuts!! They're very sensitive and they were having some sort of problem. The semi-flush actually helped, so I'm glad that I did it.

Now I'll let them dry out and get back to normal. But I wanted to nip this in the bud... I've heard these fuckers will herm pretty easily... so I have been paying extra attention to them.

Well pay that extra attention more visually than actual doing stuff. You are going to give yourself an ulcer dude. LOL You are too funny

Doubtful your ph numbers are accurate. FFOF is properly buffered near 6.5 to 7.0 ph, I believe. That's where it should stay for a couple of months till the buffers fade.

What are you using to check runoff ph? If it's a color-coded result, (freshwater aquarium ph test kit, ph test strips...) the tinting of the runoff will skew results. :eek:

If using a ph pen, it likely needs calibrating.

Or, you are re-using soil.

Or, they forgot the buffers in that one bag of mix.

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Originally Posted by lampost

I question that distilled water too... got it from the supermarket. But my pH meter was calibrated and it's a good pH meter

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I've noticed a lot of the distilled carried in supermarkets is adjusted up. Probably so it's more suitable for mixing baby formula and stuff. Don't wanna give Junior heartburn. :D

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Originally Posted by EvilCartman

I've noticed a lot of the distilled carried in supermarkets is adjusted up. Probably so it's more suitable for mixing baby formula and stuff. Don't wanna give Junior heartburn. :D

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In researching the PH, I learned that true pure distilled water has PH of 6-7, but it rises as it absorbs carbon dioxide from the atmosphere

Pretty cool huh:jointsmile:

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Originally Posted by Rusty Trichome

Doubtful your ph numbers are accurate. FFOF is properly buffered near 6.5 to 7.0 ph, I believe. That's where it should stay for a couple of months till the buffers fade.

What are you using to check runoff ph? If it's a color-coded result, (freshwater aquarium ph test kit, ph test strips...) the tinting of the runoff will skew results. :eek:

If using a ph pen, it likely needs calibrating.

Or, you are re-using soil.

Or, they forgot the buffers in that one bag of mix.

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I guarantee that pH is correct. I have an Oakton pH pen that I calibrated before and checked after. It was dead on! I also confirmed with a ph test strip. The ph numbers are accurate unfortunately! I did notice the nitrates were off the charts! Total hardness looked about 400 ppm.

I thought the same thing... They forgot the buffers in this bag! Who knows. I've heard others say they had low ph (5.0) runoff from FFOF too, with little problems. I think FFOF is over-rated! I'll use something else next time. I even added my own buffers (albeit a very small dose, 5-6 tablespoons per bag of FFOF.

The fact that redtails was unable to save a ph-skewed plant scares me. Is it too late to sprinkle some dolomite lime on the surface and hope it will infiltrate the soil?

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Originally Posted by WashougalWonder

Well pay that extra attention more visually than actual doing stuff. You are going to give yourself an ulcer dude. LOL You are too funny

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Yeah, I'm taking this shit pretty seriously. I'm unemployed right now so I've got nothing better to do. Also, I put a lot of money into this, probably $1500-2000 when all is said and done. This is my first crack at this too, so yeah, I need to make sure things are going right.

Do you rinse the ph probe between use? Nutrient build-up can occur there, too.

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Originally Posted by lampost

The fact that redtails was unable to save a ph-skewed plant scares me. Is it too late to sprinkle some dolomite lime on the surface and hope it will infiltrate the soil?

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Fresh soil, and a transplant. If you're going to lose them anyway...
I've transplanted ladies in late flower to save 'em, but you could very well pay a price. If not careful you can break branches or roots, they can go hermie and might not finish completely before you have to harvest them. (fully formed nanners) If no stress, and all goes well...slow/stunted growth likely till harvest. Might even stretch a tad if there's enough nitrogen in the fresh potting soil, but buds will likely be underformed.

If getting desperate, and you know for a fact you are losing the soil buffers, (ph swings, nutrient lock-out) I might be tempted to grab a gallon of water, and add a cup of lime and disolve as much as possible. Add it to the pot slowly. Flush it through with another properly ph'd gallon of water, so it's not all sitting on the top layer...and keep your fingers crossed.

^thanks!

I doubt FF forgot the buffers so I'm hoping it was just kind of a hot bag. Hopefully, the plants will show recovery soon. In my research it seems like a lot of people get pretty low runoff from FFOF. A lot of people are also saying runoff pH is a terrible indicator of soil pH! So, I'm gonna take it slow and hope that the plant starts looking healthier. I think the symptoms were from nute-burn. I'd given them the same dose as my larger plants and I don't think they were ready.

Anyway, nothing to do now but wait. I'll keep you all posted as to what happens with them. Shit, I should get a grow log going soon so I don't have all these scattered questions everywhere.

OK after all of my research I think this simple over-fertilization. Here is some info taken from a sticky post on rollitup forum:

"1. Over-fertilizing - the most common cause of leaf cupping aka leaf margin rolling, leaf margin burn, and leaf tip curl/burn is the overzealous use of too much plant food in relationship to factors such as plant size, vigor and rate of growth. The first unit of a plant to show moisture stress is the leaf at its margins and/or tips, reflected by margin rolling (cupping) or burning. Sometimes copper colored necrotic spots show in the leaf also. A hard, crispy feel to the leaf frequently occurs as well, as opposed to a soft and cool feel of a happy leaf. When you have a high concentration of salts in solution (or in the root medium) compared to lower salinity levels found in the plantâ??s tissue, water is actually drawn out of the plant across the root gradient in order to fix the ppm imbalance. IOW, this is a natural, osmotic response that serves to equalize salinity levels on both sides of the rootâ??s epidermal gradient. Back off on the amount and/or frequency of plant food. Too much plant food can also burn the roots, especially the sensitive root tips and hairs, which then creates another set of problems such as nutrient deficiencies. A note for the bio folks - as soil dries, the concentration of the remaining salts rises further exacerbating the problem. Leach (flush) your pots once in a while to get rid of excess salts."

I'm pretty sure this is it. The low pH (5.0) runoff is probably not causing any problems. I'm convinced that runoff isn't a great indicator of actual soil pH. All the symptoms are probably attributable to the over-fertilization with organic nutes (Humboldt Grow & Bloom Natural). Unfortunately, they may get worse as the soil dries out over the next several days. Although I gave it a semi-flush and this may've helped.

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Originally Posted by lampost

The low pH (5.0) runoff is probably not causing any problems. I'm convinced that runoff isn't a great indicator of actual soil pH.

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Runoff ph indicates the interraction between soil ph and water ph, and yes...it is an invaluable indicator. Nutrient uptake is limited on the outside edges of our ph. Lockouts will occur.

Are you adjusting the water before adding the nutrients? Every nutrient I've ever worked with is acidic (FF included) to some extent, and will lower your ph.

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Originally Posted by Rusty Trichome

Runoff ph indicates the interraction between soil ph and water ph, and yes...it is an invaluable indicator. Nutrient uptake is limited on the outside edges of our ph. Lockouts will occur.

Are you adjusting the water before adding the nutrients? Every nutrient I've ever worked with is acidic (FF included) to some extent, and will lower your ph.

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Well, the plants that had the problem have only had nutrients once. And I mix the nutrients and then later adjust the pH, however, I probably won't even adjust pH anymore. Tap water is at about 7.8 and after nutes it can come down to 7.1 or so. Just a 1/4 tsp of pH down per 5gal will get it at 6.9-7.0. I'm watering on the high-end of the range or neutral...

What I meant was Humboldt Nutrients doesn't lower it that much... not as much as I expected. It can lower about 0.2 - 0.7 pH so far from what I've seen depending on the nute combo used and the concentration at which it's mixed.

I agree that runoff pH is helpful.. but I think the pH is probably different at any given location in the pot... so even though it may be at 5.0 when it comes out of the pot... all hope may not be lost

Well, plants are doing OK. It's about 6-7 days after flush. I watered with pH 6.9 water and runoff was 6.0!!! Wooohooo!!

I'm CERTAIN that my pH readings have been correct. Last week when I first got the pH 5.0 on the Headband I measured the runoff on the healthier plants and they were all like 6.0 - 6.5.

The problem was too much nutrients too soon. When flushing I used a test strip to determine the nitrate of the runoff and it was like 300-400 pm (extrapolated since it was out of color range of test strips). Now it came down to about 20 ppm.... that is a HUGE difference!!

I've heard the curled up leaves edges may not recover! That's kinda weird, makes it hard to see how much they've recovered. But I think things are back on track now for the Headband!

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Originally Posted by Rusty Trichome

Runoff ph indicates the interraction between soil ph and water ph, and yes...it is an invaluable indicator. Nutrient uptake is limited on the outside edges of our ph. Lockouts will occur.

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What Rusty is trying to say is shown in this handy PH nute uptake chart from the charts and graphs section of the problems section of the growing section. Glad you're back on track.

^Thanks.. I'm familiar with that chart.

I'm still not convinced that runoff pH is consistently a reliable indicator. I don't think the pH of my soil swung 1 point in the last 6-7 days, whereas the runoff did. Nonetheless, I do think it's a good "tool" and I'll continue to check it.

So glad to hear you've got it all figured-out. Good luck. ;)

I have this same exact problem. FFOF and runoff at 5.4. My two sensi star plants which are in 5 gal buckets in the 4th week of flower got flushed with about 20 gallons of 6.8ph water. Runoff PH didn't budge. AT ALL. Biggest/Oldest fan leaves are crunchy and orange and dying. I don't know what to do.

My White widow is now showing rust colored spots on it's big fan leaves. Sooo, flushed the crap out of it last night. Again, 20 gallons, but I used HIGH PH, 7.5~8. Runoff stayed at 5.8 the entire time. I even added in 6 Tablespoons of lime. No budge. I'm pulling my hair out.

My other two plants, a midnight kush and a power kush are on the same feeding schedule, with the same soil...no problems. Just the sensi and the widow so far.

Any suggestions?