Not sure of the diodes. Need about 40w more. 80w would be better if using the same lights, as Id sat a 160w Samsung LED would outperform your current set up, with the same watts.
I dont know your sq/ft?????
NEVER let the medium go totally dry.
I use both a moisture meter, a cheap one from Lowes/Walmart, Mositer-PH-Light Meter, and have also been growing long enough to know by the weight, but I still use both methods, and I never let the needle get to the Moist line. Always only LOW MOIST, then I water.
If you let the medium get to dry, you will concentrate the dissolved solids, and when they get rehydrated, can potentially burn the plant. If you also feed at this time you can suffer a double whammy. Never let your plants get really dry. Leaves can also fall off.