The reddish brown spots and leaf discoloration of that sort can be caused by either over watering or iron deficiency.

You said you are in hydro.

What type of hydro system are you using?
What is your watering frequency?
What additives are you using?
How often do you check your ph and ec?

If you water your hydro plants 24 hours a day they can get root rot. The roots will start to get brown and limp. The water will smell kinda like pond muck. Your plants may seem like they are in decent health until they fall over all of the sudden and they are dead. this occurs if the rot has gone too far before being treated.

If you do not have root issues get yourself some botanicare's cal/mag and follow the directions.

You may also want to try some aquashield or some other product with bacillus therinjensis (BT) to add to your res to keep water cleaner for the week.

Jay Frost

What type of water are you using? For example: tap, distilled/RO, etc.. The reason I ask is because I use watermill express water and used to have a similar deficiency. Like Element4NorCal says, it's either an Iron (Fe) or Magnesium (Mg) deficiency. Fe affects the new growth but not the lower leaves while Mg affects the middle and lower leaves first. Iron occurs on occasion, but Magnesium is much more common. I used to use General hydroponics CaMg+, but due to a switch in nutes, I now have Ca and Mg in seperate formulas to better fine tune the feed. Best of luck!

I already got GalMag and added it this morning. After reading all last night it seemed like it could be Calcium, Magnesium, or Magnese from the pictures I saw so I already did the CalMag. I'll see how they react to that. But in case the problem is still there...

I am using a Rainforest which is like a combination of DWC and Aeroponics. The roots are always hanging into the solution and there is always an Aeroponic mist above the waterline. I am using bottled RO water, the most expensive part of this whole process.

I am using the GH "expert" schedule, currently on the "Bloom" formula at about half strenth. I check the water every day. Yesterday it was 1100 PPM, 5.8 PH, 69.9 degrees. Water was changed on Monday.

When the light comes back on I will look at the roots, I haven't done that yet. If the CalMag works will some of the damage clear up or will new damage just be prevented?

Calcium is semi-mobile.
Magnesium is mobile.
Manganese is not mobile (I personally would not consider this one, but that's just me. Mn deficiency is rare).
Unless the damage is slight, leaves will not recover from deficiencies.