Cant drop PH in FFOF , ladies looking beat up

Hey guys! Its my first grow and I’m having some issues I was wondering if you guys can help. My ladies are about 3.5 weeks old and are having major nutrient deficiencies. Im growing 6 auto flower females. Northern lights x blueberry.

Im using Foxfarm Ocean Forest soil approx 3 cubic feet of it.
My soil mix is 75% FFOF, with 25% perlite
I heard fox farm has a tendency of going fairly acidic with the peat moss in it so I added 2 cups of powdered dolomitic lime to the the whole batch of soil to keep it from going to low in ph.
I also added 4 solo cups of diatomaceous earth to the batch also. I mainly added it for the gnats normally found in FFOF , but it also adds silica and holds some moisture.
I’m using 5 gallon fabric bags.
Mars hydro 1200w LED light
RO Water

My grow room has plenty of moving air and circulation. Thats nothing I worry about. The RH is around 50-55% with temps of 24-26 Celsius (75-80) Fahrenheit.

I did a slurry test on the soil before I planted the seeds and I was getting around 6.3 ph of the soil. However I forgot to redo it after added the powered lime. ( I just realized this today lol). Im thinking this may be part of my issue. I Went away on my trip just after my seedlings poked their heads up . I pre phd my water so my roommate just had to water while I was gone for 2 weeks. I didn’t think he had to feed any because fox farm is rich in nutrients , and microorganisms. I didn’t realize that plain RO water that was phd to 6.2 would sway very much. But when I got home, I tested the water he was feeding them and it was around 7.9-8.1! Plants at the time had grown a bit however had some rust spots on them and couple burnt looking ends on them. I immediately started feeding my plants 6.2 ph water every couple days . Maybe a liters worth each. They have still kept growing but deficiencies are continuing .I did a slurry test and found my pots were sitting at around 6.9 ph. I thought maybe giving them a gallon of 1/4 dose of fox farm nuts phd to 6.0 would help , just enough water to have a small runoff. that was a day and a half ago. I Redid a slurry test and got couple of them down to 6.7 but they still look like crap. My question is when the get thirsty in the next day or so should I flush them heavily with 5.5 or 6.0phd water and waste all the good micros and nutrients in the soil just to bring the ph down? I Also read giving them a TSP of vinegar or apple cider vinegar to a gallon jug will help. Thoughts/ suggestions? I will post pics tomorrow. Since they are auto flowers 3 out of the began early bloom . I would like to figure this out sooner the better!

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I know I have 2 ladies in one pot, that might be an issue but its for of an experiment.

I would definitely flush and get that ph in range. I would also do a ph runoff test. Not a slurry test. If your ph gets to low or to high, nutrient lockout ensues and they can’t intake the nutrients in the soil anyway. It’s best to get you ph in range now. I am not the expert here, but I have learned a lot from the experts here. My understanding is not below 6.5 and not above 7.0 ph. Anywhere in that range is good for soil. It doesn’t have to be exact.


Welcome looking at the pictures the new growth on the plants look healthy is your pH meter correct it could need a calibration. I would start and make sure my meters telling me the truth. Good luck

When I tell you what happened so don’t kick your self … OK ?

When you gave it Dolomite lime you mad the soil p h go up.
That’s why your p h is so high. I’m not to sure on how many flushes it’s going to take to get your p h down to 6.5 or so.
Mite just be easier to transplant into soil without Dolomite




I got 'a tell ya that was a great answer and you have come a long way that’s for sure. 1


@garrigan62 Thanks to you I had that answer. I am still learning and I have a ways to go. But I read, read and then read some more.

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And that’s exactl how we all learn … READ !


How much water should I flush with and what ph should I flush at ? I added the dom lime as a
Precaution to it wanting to turn acidic! I think I t back fired lol . And my ph pens are calibrated fine , I appreciate the answer backs !

I think flushing with the desired ph water is fine. It’s probably going to take about 3 gallons or more. Really the trick is to continue flushing and checking ph until your run off is at the desired ph. Your plants might show a little sign of overwatering but they will recover fast. The next time you are ready for water you still might find the ph high. And you might have to flush again. I have flushed my plants 3 times in the last week and a hafl trying to get my ph up! lol

General consensus about 3x the amount of pot size. So a 3 gallon pot would require 9ish gallons of water ran through to get a good flush.

As far as setting ph of flush, it really depends on what you’re trying to do. In most cases setting ph about where you want target to be is good enough. I have also had success setting a couple tenths on the other side of target from wherever it currently sits, for the first couple of gallons. Then as ph came closer into target range I adjusted ph of my flush water to target range.


@dbrn32 Thanks for that. I just thought that since he wasn’t flushing to get rid of nutes and was only trying to lower his ph, that he didn’t need such a heavy flushing. There I go again learning something.

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That’s a lot of water ! Should I use my RO water? It’s a pain in the butt getting it but I can . Or should I use my tap water , let it sit out for a day so the chlorine can evaporate off it ?

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You may be entirely correct. Thats kind of why I posted part of maybe taking a look after couple gallons.


Depends on what’s in your water. Letting tap water off has and then adjusting ph is probably good enough. Maybe you start with that and finish with ro if it’s a concern.

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Thanks ! Since ima flush them soon should I wait for them to dry up a bit more or start it now.

They are likely going to be little droopy regardless, so you may as well flush now. Just give them opportunity to dry out after. Also, please try to omit the language too. Thanks!

Thanks ! And sorry about the language . Just a habit.

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Hey guys I’m not sure if I should start a grow journal or keep posting on here. Just an update on my grow. Im learning lots, learned humidifiers plug carbon air filters. Heres couple pictures of them.PNG|281x499

anyways the last few days I’ve been having issues with the bigger 3.

as you can tell them look sad (I think) they look over watered. The one in the front of this picture was fed with a plain watering last night of 6.5, runoff was 6.7. The ppm runoff was 557 which is fairly low I know but the previous feeding was around 770ppm (1/4 strength) and it was getting slight nute burn. I watered her with about 6 litres of water which gets me about a 10-20% runoff. Other than the droopy looking leafs look fine, no deficiencies that I can see. She looked fine at lunch but I come back after work and she looks depressed as hell. picked up her 5 gallon fabric bag and it was still pretty heavy. when I watered her last night her pot was super light so I knew it was time to water.

She doesn’t look too bad but she was watered 2 days ago and just started to droop tonight which I thought indicated she was thirsty but pot is still fairly heavy.

she was also fed 2 days ago just like the girl above but she’s drooping even more, her pot is still heavy too.

They are showing signs I think of over watering but not really deficiencies that I can see. what is going on? I wait till they are pretty dry before I water and I wait till they indicate they are thirsty . Am I under feeding them nutes? I know I should be up to around 1000ppm but I was getting nute burn that high , even though fox farm indicates I should be feeding around 2000ppm now which is crazy. Please Help!! temp is around 23-26 celsius with a R/H of 30-40%, led grow light is 26 inches away.

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any suggestions?