Help! Autoflower day 21. Overdosed on calmag, ORANGE spots on lower/middle leaves 2 days later

[kreikrei]

Hi!
I am a beginner grower. I topped the plant on day 20. Maybe thats why its a bit droopy.

Setup:
3x3x6 tent
400watt lights (mars ts1000 and 240w kingbrite board)
3 gallon pots, Biobizz light mix+ biobizz nutes
RO water (and biobizz calmag)
Environment - 22-25celsius and 55% humidity, lights on 24/0. Ppfd/DLI in normal range for this stage. Also have a decent osciallting fan and 2 small pc fans.

Problem:
During my first big watering (day 19 and 2-2.5 liters of water for 3 gallon pot) I accidentally gave about 250ppm of CALMAG
Why? Because I didnt know PPM meter doesnt measure organic calmag correctly.
I thought I put in 50 ppm (RO + calmag), but the true number is closer to 250ppm of calmag.

1 day later first 2 leaves got orange spots
Now - 2 days have passed and 3-4 leaves have orange spots.


Is this PH lockout? Or a deficiency? Should I give nutes or the opposite - do a flush?

I havent given any nutes yet, I will water today/tomorrow.
The plant was given 80% RO and 20% tap water for the first 18 days, no nutes.
Only feeding was 2 days ago with 250ppm (Ro +calmag)

Thanks guys and happy growing!

 

[Creeperpark]

Just drop the cal mag down to "almost nothing" and start giving bio biz nutes at 1/4 the manufacturer recommendations. Wait until the watering day before you do it. Catch some of the runoff from a clean tray and check the EC and pH.

 

[kreikrei]

Just drop the cal mag down to "almost nothing" and start giving bio biz nutes at 1/4 the manufacturer recommendations. Wait until the watering day before you do it. Catch some of the runoff from a clean tray and check the EC and pH.

Thanks.
Ill probably just mix 80% RO with 20% tap to get 50-100ppm.
Can I ask a more general question?
When would a flush be needed in a situation like mine?

For example, I give very little calmag and 25% nute solution, but the orange patches spread without stopping until next watering days. (Probably in 3-5 days) Do I assume its a PH lockout, because the feeding didnt stop whatever is happening and flush?

How much info you need in general to deduce that a flush is needed? Assuming you dont own a ph pen.
Thanks again!

 

[Creeperpark]

The only way to truly know when to flush is by taking a sample and testing it. If you knew what the ppm and pH are, you would know everything you need to know to make that choice.

On a watering day, water your plant well and then wait about 30 minutes. After 30 min. take some distilled water from the store and add about 250 ml of the water to the already watered pot and catch it in the bottom drain tray. Test it and tell me what the EC and pH and I will tell you if you need to flush or not.

Now, friend if you don't have a pH or EC meter then that's what your problems all stem from. When you ask the grower most of them will base their answers on the experience gained from having meters. Get your meters to test all your liquids. .

 

[kreikrei]

The only way to truly know when to flush is by taking a sample and testing it. If you knew what the ppm and pH are, you would know everything you need to know to make that choice.

On a watering day, water your plant well and then wait about 30 minutes. After 30 min. take some distilled water from the store and add about 250 ml of the water to the already watered pot and catch it in the bottom drain tray. Test it and tell me what the EC and pH and I will tell you if you need to flush or not.

Now, friend if you don't have a pH or EC meter then that's what your problems all stem from. When you ask the grower most of them will base their answers on the experience gained from having meters. Get your meters to test all your liquids. .

Thanks for the detailed answer.

I actually do have an PPm/TDS meter, but it turns out, they have problems measuring ORGANIC nute ppms. And I use biobizz organic line. So I have to rely on using the syringe precisely.
Reading forums about deficiencies it seems that very often PH is the leading cause, not deficiency. And often people make it wors by just adding more nutes.

I think a good PH pen (heard Bluelabs is decent) is actually a very good investment, I should buy it.

If I remember correctly, Biobizz has said that measuring their runoff will show incorrect results, since its organic? I guess one more argument for a PH pen

 

[Creeperpark]

Any liquid you use in horticulture should be monitored. All liquids can show electric conductivity whether they are useable salts or not. Just because you don't know the individual nutrient content of the salts doesn't mean it's not important to monitor your EC. If I'm using an organic mix that has 4000 ppm to start with I can watch it decline or increase over time. In any horticulture setting one needs to monitor both the pH and EC. Unused salts are still salts that will become available with water and so by monitoring your EC you can see this because the soil is always changing. I hear organic growers don't need to monitor their media and it's just not true. All liquids readings can give very valuable information to help see what state the soil is in and how pure the water is. A good commercial grower knows his EC and pH when he has a problem in a greenhouse setting. Test everything until you know what's what friend.

 

[X15]

I would definitely recommend letting your plants rest for 4-6 hrs per day. “auto flowering” or not, 24 hrs of light just isn’t a good situation my friend. And a waste of electricity.

 

[X15]

Or more. I offer them as much lights off time as I can… taking into consideration their make up of course, origin. It’s great to find out what the parents went through if possible too.