It can't hurt.
I just never do it for organic growing, never felt the need. But I don't really use much bottled organic nutes so maybe bottled organics might build up in soil and need flushing.
I never flushed my plants when I used pure blend. I did when I used salt nutrients, it's one of the reasons I switched to organics as was a pain in the ass to flush and was a waste of water in my eyes.
7 days seems like a stretch to me. How is your humidity levels since we last talked about it yesterday?
These plants are still really getting their root structure established and rely on humidity to help absorb the moisture they need.
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I use the Hydrofarm. My neighbor bought a high end Apogee. We checked side by side under HLG, Growers Choice 720, Phlizon 640 watt and several smaller LEDs. My cheapie was within 10 at the worst and averaged 5 ppfd difference.
A hell of a lot better than a guess. I’ll promise.
I put a baking pan in the tent and added a bit of filtered water in it and that raised the humidity by about 10% on avg, so its doing better. At this very second it's reading 45% RH at 77.5F. As far as the plants in the back go, 7 days for a tiny unestablished plant in a 3 gal pot is pretty normal for me at least. The soil an inch below the surface has a bit of moisture, not too much though, but I just stuck a moisture meter in there and it still reads at a 10 about halfway down the soil. I will say, however, that I did probably over-drench the soil when I planted the clones. I got a little carried away with trying to even out the soil around the clones when watering and ended up giving them quite a bit more water than was probably necessary (my tendency for perfection often shoots me in the foot like this). I don't exactly remember but I think I gave both of those three gallon pots around 2 gals of pH 6.5 water each and didn't even realize how much water I had used from the bucket until after I watered them in. Come to think of it I hope I didn't accidentally flush out my soil.