Problem I keep running into

[DogterB]

Problem: started with a little leaf tip discoloring and progressed to this. I was out of town 1.5 weeks and came home to her in this condition. I run into this in early flower. Previous grows I thought that I had too high of Ca in my water along with the lime in the soil. I cut the soil with 25% pro-mix to try and lower the Ca amount and have switched to RO water but the same problem has arisen yet again.
-Medium/grow method: DIY octopot wannabe, 7 gallon fabric pot with net cup in reservoir. Soil is homemade with 1:1:1 compost, base potting soil, and coco coir, with Dr. Earth Homegrown and Flower Girl, EWC, epsom salt and lime mixed in. Soil has baked for several months before use. When potting the soil, I put several tablespoons of Dr. Earth Homegrown and Flower Girl in buried trenches.
-Feed and supplements used: soil mixed with Dr. Earth Homegrown and Flower Girl mixed in, along with some EWC, epsom salt and lime. A little dynomyco at seed planting. I topdressed with EWC and watered in with LABs a few weeks ago. Only have added some Southern Ag Garden Friendly Fungicide to the res a couple of times. Otherwise water only to this point.
-Water source: RO/DI water using an AquaLife RO Buddy on my tap water
-Strain and age: Sour diesel photo by Seedstockers. Day 75, F 32
-Climate: 3x3 tent, temp 76-82F, humidity 64-69%. 12/12 light cycle
- Light used: Mars Hydro FCe3000, ~16” above net, at about 60% brightness. Photone app reading ~750 ppfd, slowly bringing it up.-Additional info: First real attempt at a scrog. Any help is appreciated, as always!

--Pictures

 

[DCLXVI]

What is the pH in the res? Perhaps it does not matter. Just the only thing I can think of right off.

 

[DogterB]

What is the pH in the res? Perhaps it does not matter. Just the only thing I can think of right off.

Aw man, I just checked and it’s in the 5 range, I only have pH drops to check with. I do have an air stone in the main res, runs 15 min every 3 hours or so. Is it the air stone? Water pH is 6.5 coming out of the filter, again with drops to test.

 

[DogterB]

I have drained all the water and replaced it with fresh water, pH’d at 6.5. Fingers crossed this is the issue. If so, how do I avoid this in the future? I checked some water jugs I had filled last week and they were all around 5.0 pH also. Is it just from the water sitting too long?

 

[DCLXVI]

RO water will absorb CO2 from the air and become acidified. A light mix of nutes can help hold it steady. I like to use silica as a pH buffer. It raises and holds very well. It is also good for plant health if you are not using it.

Is your reservoir water a blend? I was going to write more but I'll put it in your thread.

 

[DogterB]

RO water will absorb CO2 from the air and become acidified. A light mix of nutes can help hold it steady. I like to use silica as a pH buffer. It raises and holds very well. It is also good for plant health if you are not using it.

Is your reservoir water a blend? I was going to write more but I'll put it in your thread.

Ah, maybe that’s the issue, using RO and it sitting? I don’t know what you mean by is the water a blend?

 

[DCLXVI]

Oh I was curious if the water is tap/RO blend. If it's straight RO and sits open to air it can acidify. If it's blended there is probably enough "stuff" in it to prevent that and then the problem might be something else.

 

[orange wing]

Hi pal it will be something on this chart you say your ph is falling whats your ec and water level if all is falling it will be what DCLXVI is saying

 

[DogterB]

Oh I was curious if the water is tap/RO blend. If it's straight RO and sits open to air it can acidify. If it's blended there is probably enough "stuff" in it to prevent that and then the problem might be something else.

Yeah I’ve been using straight RO. Should I try blending in some tap with it?

 

[DCLXVI]

Yeah I’ve been using straight RO. Should I try blending in some tap with it?

Man o green has a fix. I just can't remember what he suggested. It's not letting me tag him right now either. I store my RO in the gallon jugs it initially came in from the store with the cap on. Limited air exposure until I'm ready to mix.

You could either store it in closed containers, mix your nutes closer to the time you collect the water, or use the light nute mix Man-O suggests. Hopefully he will swing by. I know it's mentioned in his threads somewhere to add a small bit of something, just 50ppm.

@Mañ'O'Green ! Ah! There it worked.