Amnesia Haze Auto flower - Runoff extremely acid! Help

Hey all!

I’m experiecing a situation very strange and although ive looked a lot for help with long time growers and in a bunch of places i couldnt nailed it.

The situation is that the flower was gorgeous, i mean everything was just perfect until 07/08 when the runoff PH went down to 5.4 (entry 6,3). Since that day, it never came back and the plant started to show the signs of stress and deficiences.
On 07/18 i did a flush to reset and the final runoff was 6.0.
Two days later on 07/20 i gave ferts with PH 6,3 and the runoof was 5.1!! I mean… how is this possible since the soil was suposed to be “empty”.
Today, 2 days later again, i watered with 6,8PH in an attempt to equilibrate things and the PH runoff was 5.0. I have just an idea that there must be some microorganisms, bacterias or etc in the soil and/or the roots activyt that may be resulting in a acidic enviroment. The problem is how to correct.

Strain: Amnesia Haze Auto
Age: 11 weeks
Flowering: 4 weeks.
Ferts: Biobizz and Rapidtsart.
Soil: Inert, Peat + Perlite (70/30)
Pot volume: 10L
Vent in and out OK.
Light: 120W Quantum board.
Grow size: 2x2

I always control the PH and PPM of entry and the runoff.

I was thinking in maybe abort biobizz and change now to mineral nutes that i already have, the entire Remo line, since the absortion will be faster and its easyer to correct some aspects and also considering that the problem might be something related to the microorganisms due to biobizz.

I’ll post the pictures on day 07/08, 07/18 and 07/22

I’ll apreciate a lot if somenone can help with this situation.
My last run was a banana kush auto that end up with 52g.

Thanks a lot.


Your growing an auto it needed to be in a bigger pot the one you have it in is only 2.5 gallons I don’t believe you can transplant it since it’s an auto I will get some help to you hang in there and good luck I’ll be watching to see how they finish @Mark0427 @yoshi @pptrsha1

1 Like

i have transplanted autos a few times. it didnt seem to hurt all of them. i like 5 gal grow bags but i have seen people do great stuff in 3 gal. heck even solo cups! until you do it you wont ever know for sure. :grin:

1 Like

Peat is what’s causing your acidity issue. Bacteria would help but the kinds that work in a hydro style environment like this are pretty expensive. I personally wouldnt recommend using peat for cannabis. 3 gals is about the recommended size for coco. And is the better alternative to peat.
Peat soil has a pH ranging from 3.7-5.2 with an average pH of 4.5 (acidic), does not contain pyrite, ash around 1:13% - 43.88%, and the content of organic C ranges from 32.55% - 57.35%.


@Budz seriously ? You going to have to devalue the chemistry trigonometry formulas and put it in plain English, everybody is not on a professor level if you had no idea , IJS , maybe 2 of of us finish college :thinking:!!


Hey man!

Its not the first time, and always used the same soil of the same brand. And thats why its intriguing me.
I keep everything under control, the notes are always complete and with the all the infos. I measure the parameters very carefully…
Yes, peat is acidic, but you can mantain the enviroment PH cnotrolled with the water and feedings. But not this time. Seems like something changed in there and i dont think that keep pushiung the PH on entry will solve nor its the best way…

And whats your opinion to solve the problem?

1 Like

Thats a new for me… Never heard that this size of pots was not good for autos. Ive run a few and always was ok. Ill put it in motion next time.

1 Like

Ok so here is my o2 on this with autos. Ive grow autos in 5 7 and 10 gallon fab pots so far. W0 gallon does give a bit bigger plant takes alot longer than a 7 gallon to finish and the 7 took like 2 weeks longer than a 5 dif so each step up added about 2 weeks xtra time. If it was me from now on i will do autos in 5 or 7 gal max as 10 was not that much of a difference in weight off the tree. 7 gallon i got best out of so far. Here is 2 plants sane age and all one in 7 gal 1 in 10 gal and the 7 gal buds are triple the size but the 10 gallon just started packing on a bit the other been going strong for almost 2 weeks

10 gal fab pot :point_up:

7 gal fab pot. :point_up:

See the differences same exact age and all.


Good info, bro!

But what about the main problem, the acidity of the soil? Know how to solve that?



I don’t have pH issues. There are about 7 rhizo and a couple myco in my soil. Have yet to have my coco go out, it’s not peat. Coco coir has a neutral pH range of 5.2–6.8. prevention is the best medicine.

1 Like

@kaptain3d @Arrow @CMichGrower @BobbyDigital @PurpNGold74 @Covertgrower @Myfriendis410 one of these guys might be of best assistance.


Soil acidity can be addressed by top-dressing the soil with dolomitic lime.


I use baking soda when I have excess stomach acid? It helps ease my heartburn. Never needed to use it on plants with heartburn, but you likely have some on hand and may be worth a try before they die? You got a PH tester and can make sure you don’t go overboard with it.

Be warned going back a few years 4 or 5 you read a lot of organic growers talking about using B.soda. Come forward to about 2 years ago. Mostly see people complaining about excess salt build up from baking soda.
You can raise soil ph with lime. Didn’t read exactly what medIum you are using. Be careful. Seen measurements from 1 tablespoon to 3/4 tsp per gallon of soil so use caution and start low. It will take a couple water/feeds to see the rise. It’s a over time effect use patience don’t use hydrated lime or liquid. I use this:


Yes, it will definitely build up if excess is used or with continuous use. A short-term use to get things back to normal might be ok??? Just a thought I had for a quick fix to excess acid. It is heartbreaking to get into flowering and have it all go to shit.


I would do a soil slurry b4 I added B.soda. I don’t have enough experience to really argue one way over another. I just read a lot. I think to raise or lower ph of nutes lime juice and baking soda are prolly ok, but to raise the overall ph of your soil you will have to amend it. Is acidic soil a temporary problem?

1 Like

Do you have a recommended application rate for 5 gallon containers filled with peat. I am day 55 in flower and pH of runoff on a couple of plants has dropped from 6.5 to under 5.5 over a two week period. Or, is it too late for it to do much good? Let’s Grow Some Purple Kush

1 Like

I think I’d let it ride now. 5.5 isn’t bad either.

Not to sound like a smart ass.but have you checked your calibration ?? Your meter may be off. I’ve seen guys with 10 dollar meters chasing there tail all day. Just a suggestion. If you’re not using a BLUE LAB you’re guessing!

Thanks OK I will ph to normal 6.0