Need Diagnosis

I've googles for references to what deficiency this might be but I figured I'd check with the community for a second opinion.

I'm feeding them:
RO water PH'd to 5.5
FoxFarms Grow Big Nutes (6-4-4) 400 PPM

It's odd because it's only happening in the plants that are in the grodan blocks (Sour Diesel and Blue Dream). I'm using the same water and nutes as I'm using for the plants I have in DWC buckets (True OG) and those are perfectly healthy.

RO

and yes I did pre-soak the blocks in PH adjusted water before I transplanted them.

Should I flush and up the nutes to 600PPM?

Cal mag?

GeneBanker said:

Cal mag?

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OOOOOHHHH!!
okay it makes sense now.... This all started soon after I switched from tap water to RO water.

Thanks!

bjjislife said:

It's odd because it's only happening in the plants that are in the grodan blocks (Sour Diesel and Blue Dream). I'm using the same water and nutes as I'm using for the plants I have in DWC buckets (True OG) and those are perfectly healthy.

Click to expand...

You can not totally blame the medium, if the comparison in the opposing medium is a different strain.
I second Gene, The stems say CalMag. Leaves look middle stage in this pic...

bjjislife said:

OOOOOHHHH!!
okay it makes sense now.... This all started soon after I switched from tap water to RO water.

Thanks!

Click to expand...

Ah, yes that makes sense. RO water needs supplemental CaMg.

Epsom Salt is a good, quick, cheap fix. Or you can go get yourself a bottle of Cal+Mag.

I would buy some GH calmag and foliar feed them asap

Hydrowannabe said:

I would buy some GH calmag and foliar feed them asap

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Done and done. Hopefully they bounce back. I was hoping to start flowering next week