Indoor PH Problems When Flowering Begins

[ketchieshoobie]

Hello all!

I have a recurring problem growing autos. I germinate the seeds at a 95% success rate, grow very healthy seedlings up to about 3 weeks old. Then when flowering starts in earnest I always end up with nute lockout and what appears to be low PH problems. I faithfully PH my water every time I water (RO, bubbled at least 24 hours). I start feeding them at ~2 weeks.

It normally takes a few weeks of higher PH levels in my water (6.5-6.7) than normal (6.2-6.4) before the plants start to recover. I know this is reducing my yield. Also it just drives me crazy. Some strains wind up with no fan leaves remaining.

Is there something that changes when flowering starts that causes the plant to react as if the PH were too low? Does the start of flower production put a big stress on the leaves for food? Other ideas?

Soil is OF with perlite. Nutes are Dyna Grow Bloom.

Thanks,
KS

 

[stashmouth]

Ketchie-
Perform a run off test and post the results here. Help will come in a hurry.

 

[ketchieshoobie]

Thanks, will do. They are asleep now so will post results in a few hours. I was already planning a run off test tonight - good call!

 

[Mellow Yellow]

I have read that feeding your plants before they sex is not good. I know I added some Cal/Mag to my water at about 3 weeks old and that helped. The last grow I did, I had issues as well.

I was told that if your using LED's, they need some cal/mag at about that time.

 

[stashmouth]

Personally, I think your soil is just a tad low on ph, but we'll know after the run off test. Put the water in at about 6.6 or so and catch the first 4oz of run off for the test.

Probably not WAY low, may just have to adjust ph on water going in.

 

[Peekineeze]

It sounds like you might be having the same problem I am. My Ocean Forest wouldn't maintain a descent PH so I added pulverized dolmitic lime to the soil mix and now my runoff is perfect. From what I was told by the helpful peps here on AN is that low PH is a common problem with OF. Unfortunately my plants are still having issues but one thing at a time I guess. I won't be buying Ocean Forest again. I've heard good things about Pro Mix and Sunshine Mix so I will see if those brands can hold a descent PH. What symptoms are you having specifically?

 

[ketchieshoobie]

Run-Off Result

Water in was 6.6 (Hanna Digital) and the run off was consistently 6.75 across five plants. Not what I expected.

So go back to 6.2-6.4 ph for water?

Why would it be so high? I use baking soda to raise my ph, is it continuing to buffer the soil up after watering?

 

[ketchieshoobie]

Peek,

The symptoms start with spotting on the fan leaves (like low ph) then progresses to a calcium def (rusty spots). I wonder if the RO water is my problem. Our tap water has a high ppm and a high ph (7.8) or I would just use tap water. Maybe I should always add epsom salt to the water instead of occasionally doing it...

KS

 

[Peekineeze]

Peek,

The symptoms start with spotting on the fan leaves (like low ph) then progresses to a calcium def (rusty spots). I wonder if the RO water is my problem. Our tap water has a high ppm and a high ph (7.8) or I would just use tap water. Maybe I should always add epsom salt to the water instead of occasionally doing it...

KS

I spoke too soon. Your soil sounds fine. My runoff was 4.5-5.0 after adding 6.8 water. Ocean Forest is usually slightly acidic but if its that close to neutral you shouldn't be getting nutrient lock. I wish I could give you advice but I can't figure out my own plants. You said you have some rust spots? Do you have cal/mag?

 

[JM]

Run-Off Result

Water in was 6.6 (Hanna Digital) and the run off was consistently 6.75 across five plants. Not what I expected.

So go back to 6.2-6.4 ph for water?

yes

Why would it be so high? I use baking soda to raise my ph, is it continuing to buffer the soil up after watering?

yes i find baking soda carries up and holds for a long time in soil... stay in 6.3- 6.5 range...

have a look at a few charts:





also... do you have any pics? can you describe the symptoms that you get that makes you think ph issues?
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