Originally Posted by newb101 are these holes or brown spots?

Originally Posted by newb101 sounds and looks like a magnesium deficiency or too much iron.

• Heat Stress
• Over Watering
• Nutrient Solution Burn
• pH Fluctuation
• Ozone damage
  
• NUTRIENT PROBLEMS
• Root stunting
• Symptoms localized at shoot growing points
• Nitrogen (N)
• Phosphorus (P)
• Potassium (K)
• Magnesium (Mg)
• Zinc (Zn)
• Sulphur (S)
• Calcium (Ca)
• Iron (Fe)
• Manganese (Mn)
• Chlorine
• Boron (B)
• Copper (Cu)
• Molybdenum (Mb)
• Sodium
• Silicon
• Cobalt

Heat Stress Look closely, and you'll see the brown leaf edges that are indicative of heat stress. This damage looks allot like nutrient burn, except it occurs only at the tops of the plants closest to the lamps. There's only one cure for this... get the heat away from the plants, either by moving
the lamps or moving the plants.
Over Watering Don't be throw off by the fact that the plants in Figure 2 are sitting in still water, this is actually an H2O2 solution used to try and correct the problem. Adding an airstone to the tub would also help add O2 to the solution.


Nutrient Solution Burn There's a good chance that this bud was subjected to nutrient solution burn. These symptoms are seen when the EC concentration of hydroponic solutions is too high. These symptoms also appear when strong nutrient solution is splashed onto the leaves under hot HID lamps, causing the leaves to burn under the solution.
Note that if the plants never get any worse than this here, then the plants are probably just fine.
Many hydroponic gardeners see this problem. It's the beginning of nutrient burn. It indicates that the plants have all the nutrients they can possibly use, and there's a slight excess. Back off the concentration of the nutrient solution just a touch, and the problem should disappear.



Figure 5 is definitely an over- fertilization problem. The high level of nutrients accumulates in the leaves and causes them to dry out and burn up as shown here.

You must flush with clear, clean water immediately to allow the roots to recover, and prevent further damage. The find the cause of the high nutrient levels.
pH Fluctuation Both of these leaves in figure 6 and figure 7 are from the same plant. It could be over fertilization, but more likely it is due to the pH being off.

Too high or too low a pH can lock up nutrients in the form of undisolvable salts and compounds, some of which are actually toxic to the plants.