they are hungry, feed every time or every other time, i personally feed every time with salts but get your 300ppm of cal mag in there, then veg or flower to raise it to 1000-1100 ppm

need to let em drink the water and food before you water again though, other wise the salts build up, also when you water. you want like a 5 or 10% runoff, abit of water needs to run out to help remove any un-used salts