Leave Standing Water in Kiddie Pool after Flush?

i'm using a kiddie pool that's about 5' in diameter to catch runoff. works great for feeding and flushing. i'm almost 2 weeks into flowering of 3 big shrubs. plants were bone dry 2 days ago, so i did a mini-flush, watering until i started to get runoff, just to get the soil completely saturated, followed by a good feed. plants are happy.

i left about 4 inches of runoff water in the pool, mostly out of laziness. when i went to wetvac it out this morning, i noticed that the plants had drunk more than half the standing water. i can tell that they drank that much since the vermiculite and soil that overflowed from the top of the pot during flushing stuck to the outside of the pots to mark the original water line. i'm sure some of it was evaporation, but 2" of water doesn't evaporate in 2 days.

is there any harm in NOT removing that water? after all, the taproots at the bottom are in search of a constant water source, right? as long as i let it dry out between heavy waterings or flushings, i should be good, right?

think it would be ok to use this as a watering technique when i'm out of town for several days? just fill the pool up with 4 inches of water or so before i go?

dont leave standing water. its bad.

Standing water for too long is bad, it'll drown the roots and whatnot. But i always used to leave my drip trays near overflowing with water, within a couple of hours it would have been evaporated or used

happy to report that after 2 months, leaving a few inches of standing water in a kiddie pool after feeding three 15-gallon pots is perfectly fine under 2X 600-watt HPS lamps on for 12 hours. temps run around 75-85F. i usually feed 17 gallons total for all three 15-gallon pots and end up with 2-4 inches of runoff in a 5ft diameter kiddie pool. standing water gets sucked up or evaporated within about 2-3 days.

also works great on the veg side with about eight pots/bags that are between 3-5 gallons under 10X 4ft T8s. 17 gallon feed leaves 1-3 inches of runoff in a 4ft diameter kiddie pool. standing water gets sucked up or evaporated in 1-2 days.

as long as you keep the pool relatively clear of dried leaves and other organic matter, you should be okay. i haven't had problems with soggy roots, pests, or mold. i had gnats for a week prior to starting this practice, but haven't seen them since, even with all the standing water. yellow sticky traps seemed to get rid of them in just a few days.

i don't see any reason to discourage anyone from this practice.