Help whats wrong with my plants leaves turning yellow (first grow)

[SKMARTIN6]

I need help, first grow in coco coir in 4 x 4 tent, 3 gal smart pots, general trio & cal-mag nutes ( using feeding schedule from GWE site & viparspectra V1200 led light. Started light on veg the march 2nd and switched on bloom the 18th (have both on now). Every thing started out good, have 3 plants Sensible Seeds Auto's (1) Super Uzi & (2) Wicked Widow. Started seedlings March 2nd everything was going great till the 18th when one plant started to look like it had nute burn so flushed with just ph'ed water. Then on the 23rd another plant started to look like it had nute burn also, then just the other day the third plant started the same thing. As of now I'm not sure it was nute burn but from pics on GWE could be either potassium or magnesium deficiency. Started out with just tip of leaves turning brown that's why I thought it was nute burn till the leaves started turning yellow. The first 4 pics are before they started to turn the last 4 are what 2 look like now 3rd one is not that bad yet. I flushed with plan ph water twice but hasn't helped. Looking for help to try an save my girls.

[SKMARTIN6]

Sorry pics are ass backwards

[Mr.furley]

Pictures in natural light really help us help you!
what's your PH in and out story and what's your watering schedule/practice?

[billyboy]

Flush with a pint of cal-mag immediately !

j/k :-)

[Canuck147]

All your problems started when you switched your light - adjust your light or turn it just to bloom.

[SKMARTIN6]

Mr. Furley I'm using the feeding schedule on the grow weed easy site by nebulahaze, ph-ing per suggested @ 5.5 to 6.5 been staying around 6 most of the time and I checked the out a couple days ago it was at 7. Billyboy are you saying dump a whole pint of cal-mag with water or straight? Are you serious? Canuck 147 actually I noticed the brown tips on the first plant the day I turned both veg and bloom lights on together. I did turn the veg light off last night just to see what that does. The weird thing about all of this is it didn't happen to all three plants at the same time, noticed the first one turning on march 18th then the second one on the 23rd then the other a few days later. On the 24th & 25th I flushed all of them with just ph water then on the 26th & 27th used just 1/2 strength nutes. Didn't water last night coco was still damp.

[Mr.furley]

Your out pH needs to be the same number as your in pH. If you give 6.0 PH'ED water in and it's coming out at 7.0 then you have a problem at the root zone.
You can flush your plants container with 6.3 Ph'ed water next time they need water, I'd do all your plants at the same time to reset the medium in them all. Give water a gallon at a time, checking the runoff till it matchs the input.

billyboy that is not good advice to give in my opinion joking or not!

[PRIMO]

You said you thought it was a magnesium deficiency. Have you given them any cal-mag?

[SKMARTIN6]

Mr.furley Thanks I'll do that tonight, I had flushed before but wasn't checking PH out. PRIMO yes I have been giving them cal-mag per nebulahaze feeding schedule for coco-coir per the GWE site. When it first appeared it started at the tip of the plants so by the pic's on GWE I thought it was nute bure, but then the leaves started yellowing so I thought it might be potassium def. then as they got yellower thought it could be mag. def. Confusing as HELL. So that's why I'm here getting expert advise. Again it's just funny it didn't happen to all of them at the same time, it was days between each one having the problem. I know even if I can save them I probably won't get much but I just want to see them grow up to be big girls. I've gone to far to lose them now. Thanks I'll keep you all posted. Mr.furley so just keep putting 6.3 ph water till it comes out the same as it went in no matter how much water it takes? Also is tap water ok, been filling up jugs leaving tops off for several days to get chlorine out.

[Mr.furley]

Yes one right after another nice and slow. Check what you runoff is after you have empty each gallon. Make sure to "catch" a little in a small cup or dump out the old water each time, it will slowly start dropping.
Tap water is fine just make sure it's room temperature.

[SKMARTIN6]

Mr.furley Thank you sir, I'll let you know what happens.

[MadMike]

One thing to consider is that when the pH is out of range, some nutrients aren't available even if they are in the medium. A quick flush with a high Cal Mag watering won't help most likely. This chart gives a great simple look at pH and nutrient uptake. With your pH of 7.0 phosphorous becomes unavailable for instance. It seems to me that roots that are water logged will also have uptake problems - potassium in my case recently. Another factor can be light stress. I find that my plants will show deficiencies first in high light areas of the tent.

Your symptoms look like Potassium deficiency to me - pretty classic and one I've had to deal with on multiple occasions.
Follow Furley's advice. I would add that when I flush I have been trying to do it slowly. I add some plain water, let it drain, add some more, let it drain, etc. It takes time but you're more likely to full saturate the soil so their won't be pockets of coco that don't get flushed. I finish with a 1/2 str nute mix to put something back into the soil. Then I would let it dry out for day or two (depending on your temp/humid). Then I would repeat and see if the pH has changed.

I find moving the pH to be a slow process for myself so it may take more than one flush to fix it.

This is just how I've been doing it and others here might have some alternative ideas.

[SKMARTIN6]

MadMike Thanks for your input I'm going to work on it tonight.

[SKMARTIN6]

Mr.furley Just to update, I flushed the plants last night. Started with the one that had the yellowing first used 6gal. water couldn't get it any lower than 6.6. It got to that after the first gal but wouldn't go any lower. I wasn't thinking but when I made my coco coir I only did one block and I didn't have enough to fill all 3 pots so I went to a nursery an got a bag of Bush Doctor Coco-Loco coconut coir with perlite and mixed with the coco coir I had left, probably half & half. I think that is one of the problems with that one, it doesn't drain very fast.The other two only took 2 gal each, actually the out water after the first gallon on both was just under 6ph. They looked good this morning. My question to you is should I water w/ full strength nute or half, also should I go ahead an remove the yellowed leaves?

[Mr.furley]

Let your pot dry out till they are light as a feather when you lift them till you water again.
The one that you can only get to 6.6ph only give it 6.3 water, 1/2 nutrient and calmag next time, and the others mix your nutrients as normal and ph to 6.3.
The next time your 6.6ph plant drys out you should be able to feed as usual and it should have drop to 6.3ish then
Do you alternate ph'ed water and nutrient feed? How often do you water?

[SKMARTIN6]

Mr.furley Per the feeding schedule I was going by on GWE I think this week was when I was to start alternating water and nutes but has probably had more ph water than nutes because I was trying to flush but I guess I wasn't doing it right. I have been watering everyday. I read to stick your finger in it to check if it is still wet. I was having over heating problems before an they were drying out pretty fast but have that under control. I will start watering as you suggested. I really appreciate all your help. I'll keep posting my results.

[Sheesh]

Did you rinse the coco coir a few times before planting? Coco coir can have quite a bit of salt in it even if the maker says they rinsed it. Rinse it yourself 3 times, IMO. Coco coir should also be buffered with cal-mag before planting. This will help stop the coco from sucking up and keeping all the cal-mag. Read up on rinsing and buffering coco. Coco should be PH'd to about 5.7 to 6.1 IMO and the runoff PH is not as important as the PH in. Make sure you are adding all nutrients and supplements before you measure and adjust PH. Make sure your ph meter is calibrated and providing true readings. The other thing to think about is a ppm meter so you know what nutrient strength your strains can handle.

[SKMARTIN6]

Sheesh Thanks for the input but yes I did all that. I think & hope I got everything under control.