Problem with Leaves - Please Help!

Hello everyone at RIU! Having some issues with my leaves. I'm thinking it may be a cal/mag problem, but would love some other opinions. I have attached a pic. Hopefully not a mold problem of some sort. Most of the leaves look great, but I can see this becoming a problem. I am running a 10 unit recirculating DWC set up. Using tap water that has sat overnight to dechlorinate. Using Advanced Nutes with 2 600 w lights in a 4 x 8 tent. I haven't used any cal/mag due to me not using RO water, but maybe need to do so. Your information is priceless RIU, so please help me out! Thanks!

ive had the same problem from the leaf pic, the grey spots was all crisp and brittle, i wasnt able to fix the problem i even flushed 3 times

Looks more like phosphorus D to me, but it could be mold IDK i never had to deal with it.

This is all too common. You've got to do more than guess what might be the problem. If you're serious about growing like I am you would invest in the essentials; ph meter, moister and nutrient meters. This will help you out big time!

Autobahn101 - I may be asking for too much as an opinion of what is happening. If I could do more that guess what the problem is, I would not be posting my problem here.... ya think. I have been growing for more than eight years. You think I have a set up like this and am not "serious about growing like you". And I guess a "moister meter" is really an essential in a system than the roots are in water and nutrients 24/7. Yes... I have ph and ppm (or nutrient meter as you would call it). Please do more than assume someone is a nube before you try and give NO help. Sorry this is so common. I apologize if a little straight forward... but come on.

Thanks for the info Decepticon... So what was the outcome of your grow when this was happening?

Realize this is old thread but did you ever diagnose the dry gray leaf problem? I'm going through the same thing. Thanks!