Great question! we all try to outdo our last grow and become better!!   we used an RO system when i was working at the local hydroponic store (not on weed) it would really only put out about 5-6 gallons per hour. thinking about it nw, it probably needed both filters replaced. The brand was Hydro-logic similar to this one but i think ours was a "200"

https://www.amazon.com/dp/B01MYVS35X?tag=housegrail-20&linkCode=ogi&th=1&psc=1