Little yellow spots

Hello all,
I have searched a lot in the forum but could not find out what kind of problem I am experiencing here.
I am running a flood and drain hidro system with 3 tables, one for veg time and other two for flowering time.

IAM using Coco with perlite and vermiculite as medium.

If somebody can help me identify the what s going wrong I would appreciate that.
Thanks a lot
Flngrower

What are u feeding them?

It looks to me like just the slightest bit of tip burn, which means you are feeding them well Coco is not my thing though so others may know better. They look good overall though.

Welcome to RIU

diablo42 said:

What are u feeding them?

Click to expand...

Hello diablo42, I'm using general hidroponic. Micro gro and bloom.
It comes to my mind that could be the salt buildup in reservoir?

I got one more picture. With the tip and edge burnt.
Now, seeing that leave i could say it's potassium deficiency. But how? If im giving the vendor's specified amount of nutrients.
I just flush them now and check the run off. It says pH 6.7 ppm 1100.
What I suppose to do now? Adjust pH and see what happens? Flush again? Change all my reservoir water ?

Replies are very appreciated
Thank you all

If you're running hydro and your runoff is @ 6.7 pH....this is the problem. If it were me, I'd get this fixed first (my pH), give your plant/s time to settle and then attempt to fix what bothers you; remember you're in flower so go easy. Good luck.