Growing Lettuce on Raised Beds

[kitaka]

Dear All,

I am currently growing lettuce in a sand and paddy shell mixture in the Caribbean and is being irrigated using drip tape. I am confused on when to irrigate with the nutrient solution and when the irrigate with water only and how frequently. Any suggestions would be appreciated.

The hydroponic solution I am using is as follows:
For four (4) liters of water:
A. CONCENTRATED SOLUTION OF MAJOR nutrients
GRAMS
Mono-potassic Phosphate 190.0
Magnesium Sulfate 400.0
Potassium Nitrate 440.0
B. CONCENTRATED SOLUTION OF MINOR NUTRIENTS
GRAMS
Fertilon combo 20.0
Boric acid 4.6
C. CONCENTRATED SOLUTION OF N C
GRAMS
Calcium Nitrate 590
DOSAGE
Solution cc. per 1 liter of water
A 5.0
B 2.5
C 5.0