I only run one plant at a time so I store rain water in two, 5 gal buckets. I dip 2 qt containers in and store them in the tent to temper over night. I mix my nutes and pH each qt after. I tried to store pH perfect water but it fluctuated and i had to readjust so i dont touch the water till im ready to use it.
That sounds really cool about the rain water. Do you have a special system to collect it or just put a bucket out?