Just a little update for whoever is interested in how this is turning out-
At 2 1/2 weeks the root systems are getting large, the mediums that were used to clone with are staying moist from the wet lava rocks. They are very healthy and are growing very fast.
The pH was adjusted at around 1 week down from 6.3 because he doesn't have a meter yet and 10 days later the pH was 5.7 and didn't require adjustment.
The system is using a lot of water- my brother thinks a lot of evaporation is happening because of the waterfalls and the fan exchanging the air in the rez. The TDS wasn't really effected all that much by it because of the massive amount of water in the system. About 10-15 gallons in 2 1/2 weeks with small plants, can't wait to see how much it uses when the plants are flowering!
We added 3 gallons of water and the TDS didn't move LOL so I have to make him 15 gallons of RO water and I hope that's enough to bring the water level back up to where it started at.
The stability in the system is incredible though- having to check the system once every 7-10 days at this point with absolutely no problems has been very nice. He needs his own meter so it doesn't have to go unchecked for so long, but for now everything is more than fine. It used up 15+ gallons and the TDS went up by a factor of 2... Pretty damn sweet.
I'm really liking how it's performing so far!
Some new pictures will be coming as soon as they get a little bigger, thanks for reading!