italian-

Stinky is steering you straight, but I will add a little. What you have there is a phosophorous deficiency. But doubling the recipe is not necessarily the answer in your case. Do you have an EC pen? If so I would like you to check your EC daily and tell us if it is rising, falling or staying about the same. With that heat you may be transpiring too much water and your nutes may be so high they are getting locked out.

But a P deficiency is kind of rare, unless something else is going on. With that heat, have you looked at the roots lately? You might be suffering from root rot blocking any nutrient uptake.

Finally, lets try and get a cover or something on that ballast. We are taking about life threatening electrocution hazard over there.