This is the second week with nutrients
The one undel the HPS and the small one under the LED are feeded with BioBizz and the last. one with Advanced Hydroponic of Holland ( ph 6.5 each).
The pictures are not too good but u can see that the one under the HPS is too tall but the internodes are not too close. The other two have them closer.
Like the project/experiment ;) with the lights. You can definitely start feeding and it's highly suggested you do so now to help those fruits develop. Start at a 1/4 strength from recommended dosage of whatever you intend to use and week by week increase. You should get a PPM meter if you don't already have one to document how much you are giving. I'd also recommend you raise your lights as they look way to close and you will soon see signs of leaf curl or burnt pistils.