Ruh-ro, whats this?

[Bassman59]

Got this problem going on with one plant real badly in DWC. Two others starting to get 1st look towards the same. But my 4 other plants are all looking fine.

I have had problems during the grow.

They are:

1. huge ph swings - cured with nute change and going from straight RO water to 5:1 RO/tap (400ppm tap).
2. Had res temp problems early, somewhat cured for two weeks then got a chiller Fri nite and res temps are great now.

I was adjusting ph 3-4 times daily before. Now I only need a small change 1-2 times max.

here is the problem child, followed by the one that may be doing the same thing as highlighted in colored boxes.

and the highlighted ones:

Rest of grow looks fine:

 

[JB42]

Not too familiar with the set-up, but here's a bump anyway, looks like it could do with some help. But obviously it a PH fluctuation problem, it'l locking out different nutes at different times, sort that, sorry cant help more

 

[PrairiePoet]

What are your pH swings in what time frame? How big are your tubs, and how much water is in them? How much water do you have to replace each day?

pH should be moving through the day. But it should swing too far out over a day or so. For me, during veg it goes up, during flowering it goes down. Might be opposite for you, depending on brand of nutes.

 

[Bassman59]

Since adding the chiller, changing nutes to AN Sensi A & B, I no longer have big ph swings.

It appears by a few folks these plants had a Mag deficiency. Probably caused by using straight R/O water, coupled with the ph swings causing Mag lockout.

Yesterday I got some cal-mag and added at the "light feeding" schedule of 1 tspn per gal. I also foliar sprayed epsom salts on all three twice yesterday and once this morning.

It's been 20 hours and I cant see an improvement, but I dont know that it's worse either.

Should I prune off the really bad leaves on the one and hope for recovery or should I leave it alone? **Btw, on the really bad plant, the two really bad leaves are directly opposite each other and same node.

If this was the cause (likely is) I dont know what the recovery time is.

 

[PrairiePoet]

Since adding the chiller, changing nutes to AN Sensi A & B, I no longer have big ph swings.

It appears by a few folks these plants had a Mag deficiency. Probably caused by using straight R/O water, coupled with the ph swings causing Mag lockout.

Yesterday I got some cal-mag and added at the "light feeding" schedule of 1 tspn per gal. I also foliar sprayed epsom salts on all three twice yesterday and once this morning.

It's been 20 hours and I cant see an improvement, but I dont know that it's worse either.

Should I prune off the really bad leaves on the one and hope for recovery or should I leave it alone? **Btw, on the really bad plant, the two really bad leaves are directly opposite each other and same node.

If this was the cause (likely is) I dont know what the recovery time is.

If it is a deficiency, then it should stop, once you have it covered. What you are looking for it is to stop getting worse. New growth should also not show the signs.

Not sure how much that helps.

 

[JB42]

Yeah I think your right mate looks like mag deff which is one of the worst, if not sorted it could kill the entire plant.
New growth could still show the deffs, you need to wait a week , even two in some cases to see the improvement. Yeh I'd remove the damaged leaves because they will never recover anyway, they will just die off an it will be easier to see if its recovering when its all green again.