I actually ran root riot, rock wool, and peat pods all at once to see what would preform better and the peat pods where the worst with rock wool second. Your right re holding water but if on a continuos drip they all hold it. It took me a bit to drop the floods down, thinking they would dry out but nope. Once I get decent structure I can cycle pump or run continuos with no real discernible difference. Also I start at 5.6 5.7 and let it slowly rise over a week or two depending on stage. I never add back or top and just change out as need which again is 1-2 weeks, sometimes 3 if I get lazy and there’s still water in the res. I assume the res on the water farm bucket is quite small?