Every watering! That wasn’t the issue it was saving leftover water in that jug cuz once it sat it was making the solution go super acidic! Using in the grow bag would be fine but we’ll see if I have the motivation to split a water jug in 1/2 and add the LABS as needed AND WITHOUT any leftovers to drop on me! Gonna use something diff altogether in the earthbox juniors tho cuz sitting in reservoir will AND ALREADY HAS DONE the same thing it was doing in the jug and would plummet as it sat down there exposed to oxygen!