I have an aquaponics system to provide our above ground vegetables such as lettuce, spinach, silver beet etc. I have found that over summer, even when shaded the growing media is getting too hot for the roots and the plants die off (this year, 2 weeks > 42C). I am starting to covert the 1/2 IBCs to having 100mm coarse gravel with well in middle covered with weed mat, then about 150mm sand, topped of with a mixture of soil and compost and composted chicken/cow manure.
Does anyone have any experience with wicking beds? And can they provide some guidance.