Indoor Hydro/Fogponic grow - first grow diary - need advice.

[CruelSun]

Wow you got it going on!

Nice build!

Thank you!
It has been a lot of work so far, and there is still lots more to do.

 

[CruelSun]

After processing in the bubbler for a while, my tap water ends up at about pH 7.5. I'm using GH three part and mixing on the light feed chart, week 3. After adding the nutes, resulting pH is around 6.5. on the first batch I adjusted to around pH 6 but then I struggled to keep it from climbing above pH 6.5 for the whole week. I think with the next batch I will adjust to pH 5.5 after the nutes and see where it ends up from there. I'm currently using 40 gallons in the system.

 

[CruelSun]

@Moe.Red

Trying to get a handle on the chemistry here...
On my fourth round of nutes now, I've been taking lots of notes. It seems that I have to put about 10 g of pH down into this 40 to 50 gallon system daily to keep the pH between 5.5 and 6.5. does that seem excessive?

Water processed through the bubbler for a week Comes out at pH 8 plus, Saturday It was pH 8.2.
After draining as much as possible from the system, refilled to the 50 gallon mark. PH is now 7.7.
Added nutrients (GH three part, medium feed, week 3) pH went to 6.9.
Added 20g of GH pH down dry concentrate. pH went down to 5.9, then moved up to 6.2 and then 6.7 within 24 hours. Sunday morning I added 10 g which brought it to 6.1 and then another 10 g but failed to get a reading once it settled. Monday morning it was back up to 6.3 so I added 10 more grams. 9 hours later 6.3 again...

At this point pH down will become a line item in the budget... Am I doing something wrong here or is my water chemistry trying to send me the message that I need an RO filter?

To my eye these girls look peachy! Lush green. No issues that I can see. And they're growing rapidly.

The plant that looks a little thin is just the last one that got flattened out and tied down. So it looks thinner than the others.

Bottom duct is 6 in pulling air out of the top of the tent and outside up to the roof line of the house. My wife HATES the smell, so I have to do what I have to do... The 4-in duct goes through a homemade filter box to filter out pollen, mold spores and critters. It brings fresh air from outside to the lower level of the tent. No fan on the fresh air duct, but the negative pressure created by the 6-in ducted fan pulls a good stream of air in. In the last week or so, the lush growth and warmth from the light have been starting to make the main floor of the house smell like pot. As soon as I got the ductwork completed and the fan on,The pot smell disappeared entirely. Now I can't smell anything until I open the tent. Exactly what I wanted.

Each duct has a gate valve or blast gate to shut off or regulate Airflow. Also shown is fan controller, temperature controller and humidity controller, all inkbird brand, Wi-Fi/ app controllable.

 

[CruelSun]

@Moe.Red
@Mikedin
@Aqua Man

Is there a particular sub-forum where I can get some help with hydroponics? My plants seem to be doing really well but I'm having some difficulty with pH.

 

[Aqua Man]

@Moe.Red
@Mikedin
@Aqua Man

Is there a particular sub-forum where I can get some help with hydroponics? My plants seem to be doing really well but I'm having some difficulty with pH.

Have a read here and any questions feel free to tag me.

Marijuana pH Levels for Growing Weed: A Basic Explanation

In this article, we discuss proper pH levels for your weed plants; alkalinity, soil pH, tap water, and the effects of nutrients on pH when growing marijuana

www.thcfarmer.com

 

[CruelSun]

@Aqua Man

Read and understood, thank you.

Understanding is one thing, but my experience level on this is very low. I'm on my fourth round of nutrient solution in a 40 to 50 gallon RDWC. It seems that each successive round of nutes is harder and harder to keep below 6.5... I'm using what I consider to be excessive amounts of pH down (10-20g of GH pH Down dry concentrate), daily.

Tap water is pH 7.6 / PPM 55-95
I store 50 gallons in a drum with 2 air stones for a week to off-gas chlorine, until the next nutrient change. After bubbling for a week, it's pH is 7.8 - 8.2.
With nutes mixed in, solution is pH 6.9.
Adding 25g pH down brings it to 5.5 or so but 24hrs later it's at pH 6.3 or higher...
Last night pH was at 6.6. added 15 g down and this morning pH was at 6.6. I added nothing this morning to see how far up the pH would go and 8 hours later it was at 6.8 this evening.
Since mixing this round of nutrients on Saturday morning, I have added 95g of pH down.

The only other thing I've changed in this round of nutrients is that I added hydrogen peroxide for the first time. I used about half of the recommended dosage cuz that's all I had on hand.

 

[steamroller]

Have you considered RO water?
My guess is the KH in your tap is high and causing the pH bounce.

 

[Aqua Man]

@Aqua Man

Read and understood, thank you.

Understanding is one thing, but my experience level on this is very low. I'm on my fourth round of nutrient solution in a 40 to 50 gallon RDWC. It seems that each successive round of nutes is harder and harder to keep below 6.5... I'm using what I consider to be excessive amounts of pH down (10-20g of GH pH Down dry concentrate), daily.

Tap water is pH 7.6 / PPM 55-95
I store 50 gallons in a drum with 2 air stones for a week to off-gas chlorine, until the next nutrient change. After bubbling for a week, it's pH is 7.8 - 8.2.
With nutes mixed in, solution is pH 6.9.
Adding 25g pH down brings it to 5.5 or so but 24hrs later it's at pH 6.3 or higher...
Last night pH was at 6.6. added 15 g down and this morning pH was at 6.6. I added nothing this morning to see how far up the pH would go and 8 hours later it was at 6.8 this evening.
Since mixing this round of nutrients on Saturday morning, I have added 95g of pH down.

The only other thing I've changed in this round of nutrients is that I added hydrogen peroxide for the first time. I used about half of the recommended dosage cuz that's all I had on hand.

Switch to phosphoric acid. You can probably find it super cheap at any hydro shop.
i have a feeling the dry gh ph down is citric acid or mostly citric acid and that reacts with bicarbonate in your water breaking the acid down and releasing it as Co2. This makes for a very unstable PH as the acid breaks down very quickly.

phosphoric is cheap and very stable… sulphuric is another option but a bit harder to find

 

[Aqua Man]

Also 50-90ppm in your tap will have a small buffering capacity so when using a weak unstable acid like citric it will really show.

Even with phosphoric acid you may need to add a small amount of buffer like potassium bicarbonate, potassium silicate or a hydroxide. But try phosphoric acid first to see. Ideally you should be around 0.2 ph drift in 24 hrs

 

[steamroller]

My reading says both the liquid and dry GH pH down are phosphoric acid [ food grade].

 

[Aqua Man]

My reading says both the liquid and dry GH pH down are phosphoric acid [ food grade].

If thats the case then a larger buffer will be needed.

also if using tap water do not forget the ph will rise roughly 0.4 in the first few hrs out of the tap with aeration

 

[SSgrower]

If thats the case then a larger buffer will be needed.

also if using tap water do not forget the ph will rise roughly 0.4 in the first few hrs out of the tap with aeration

I am not doing bad at coco/perlite learning about good "bagged" cana or Royle Gold. I am mixing FF Coco Loco 30% to canna and the macro photo's I recently took and posted show my improvement but, your hydroponic knowledge is always on point, I salute you @Aquaman

 

[Aqua Man]

I am not doing bad at coco/perlite learning about good "bagged" cana or Royle Gold. I am mixing FF Coco Loco 30% to canna and the macro photo's I recently took and posted show my improvement but, your hydroponic knowledge is always on point, I salute you @Aquaman

I really need to make my way back into some grow threads but life is hectic and hardly time to post lately… i dod see some pics the other day and looks like you killing it brother

 

[CruelSun]

6.8 last night, added 20g of this, 6.7 this morning.
Not sure if it matters but this product is 15 years old. Stored in dark cool environment.

Test strips are brand new, bought them to verify readings of pH pen.

Will go to hydro store this evening if I can. Busy day...

Thank you all for your help so far, this is getting frustrating but the girls look great!

 

[CruelSun]

In the above picture, the test strips indicate tap water between 7 and 8 and nutrient solution somewhere around 6.
So my pH pen appears to be reasonably accurate so far. I've also tested distilled water which the pH pen reads as about 7.1. takes a while to get there but that's pretty good I think

 

[Aqua Man]

6.8 last night, added 20g of this, 6.7 this morning.
Not sure if it matters but this product is 15 years old. Stored in dark cool environment.
View attachment 1341078
Test strips are brand new, bought them to verify readings of pH pen.
View attachment 1341079

Will go to hydro store this evening if I can. Busy day...

Thank you all for your help so far, this is getting frustrating but the girls look great!

Yeah thats citric acid, sulphate and urea… that a more organic in a sense approache. Good for soil grows to adjust PH for mixing. But just not stable enough for hydro.

grab some phosphoric acid and it should drastically improve. In the end you may need a bit more buffer but start with the acid

 

[CruelSun]

Eeeek!! The powdery mildew is back!

Effing nube mistake... Got so preoccupied with the pH and how wonderful the plants look on the surface. I forgot to keep digging around and looking for hidden problems. I treated the clones for powdery mildew when I got them. The original clone pictures showed it and @Mikedin alerted me to it. I treated them immediately with milk and then with potassium bicarbonate when I acquired some a couple days later. The symptoms went away, but I should have been more vigilant, especially when the plants got bigger and taller with thicker undergrowth. But, It gave me an excuse to take off work today 😂... I still need to get to the hydro store to get some phosphoric acid, so that will happen at 10:00 a.m. when they open. In the meantime, I have sprayed them all down with potassium bicarbonate.

I do not want to make this mistake again, considering that I certainly have powdery mildew spores in and around the tent and on the plants, should I be treating these girls prophylactically, and how often?

 

[CruelSun]

How often could I, or should I, treat these plants with potassium bicarbonate to be sure I have killed the powdery mildew?

I have stabilized (?) the pH with some phosphoric acid for the moment. I'm going to change the nutes tomorrow, so we will see if the next round of nutrients can be more pH stable...

 

[CruelSun]

Have you considered RO water?
My guess is the KH in your tap is high and causing the pH bounce.

I have, and it is always a possibility, but I'd rather just use tap water if I can get away with it. I acquired phosphoric acid yesterday and I am changing the nutes this morning . I'll make sure I flush the system real well to get all the old solution out so I can start fresh.
If I can't stabilize the pH with phosphoric acid, I will dig into learning about buffering.
If I go with RO, wouldn't I need to add a buffer to that because of the low alkalinity?

 

[CruelSun]

@Aqua Man

Changed the nutes Saturday. Once the nutrients were mixed in, pH 7.0.
It took 60 milliliters of phosphoric acid to lower the pH to 5.5.
30 hours later PH was 6.6. added another 15 ml phosphoric acid at 11:00 p.m. on Sunday night.
So far Monday 6:00 a.m. and 6:00 p.m. pH 6.2... dare I to hope that it has stabilized?

Thank you for your help.