Preface: I don't really know what I'm doing.
So I decided to grow some kweik lettuce in my ebb & flow hydroponic setup. In addition to that, I'm growing a variety of chili peppers, mostly superhots.
It's been about 40 days, and I've had good growth so far, but I tasted some today and it was possibly the most bitter thing I've ever tasted.
It's growing in coco coir in an ebb/flow system, with a nutrient solution at a pH of ~5.8 and a TDS of ~800PPM, flooding twice a day at 7am and 1pm. Lights are currently on 18 / 6 cycle, running a 600 watt HPS lamp, with some thermal insulation around it that keeps the ambient temperature in the tub about 23 degrees C.
My suspicion is that it's too hot for the lettuce and that's causing the bitterness, but I also suspect that it may be a nutrient thing as well.
Can anyone shed any light on whether my suspicion is correct, and if there's a way I can save it before it's at maturity?