2 papaya from nirvana and chronic cutting in a nft gt205

well this is my second attempt with coco the 2 papaya's curtsy of nirvana seed bank and my 1st time using the gt205 nft tank which is a 3rd generation chronic cutting from a good friend.

i have a 1x1x2 tent which im using for the two papaya in 10litre bags i re-used the coco from my last grow feeding them ionic nutrients 2 days water the 3rd and nothing the 4th day unless needed(i lift them and go off the weight of the bags) i will post pics soon, a few lower leafs have yellowed at the bottom on one of the little ladies im not sure what it is, but there isn't any on the new growth so im not too botherd by it yet, should i be ??

the chronic i got from a good friend i put in a rockwool cube untill the roots came through the bottom and then into the gt205 tank in 3x3x7 cupboard lined with black and white carbon filter, extractor fan, and intake coming from the attic and an oscillating fan just above the canopy, she's been in for 3 weeks tomorrow, and i am amazed by the growth rate it, currently running the pump on 15 mins of every hour on 18/6 under a 600w hps with dimmable ballast which is currently on 450w will turn up to full 600w for flowering, also running on ionic grow nutrients at 1.6 ec and ph at 5.8.
I will post pics soon guys let me know what you think and as always any advice is welcome and appreciated thanks guys

And this is the chronic

Is she gonna fill out the space here when she goes into flowering during the stretch??

She should, easily

thanks for the reply haha i dont really want her much taller being so close to the light, but i only did the one just to see what i could yeild versus the 3 in the same space i did before this one, so hope it will be worth it. have you any experience with nft? hydro in general.