I'm doing my first dwc and I change my bucket out every week with fresh ro/di + nutes. If anything I get a spurt of nice new growth after I change the bucket out. I take the root ball, lid and air stones and put them in an empty bucket for a few minutes while I take the bucket I have been using to a sink and clean it out with hot tap water and a stiff brush. The only issues I have had is I burnt my main cola lifting the lid/plant out of the bucket, and it hit my hps bulb, burnt one side completely, but the plant fixed itself, like if I would have fim'd it, the nodes below grew bigger to compensate. Also I added 5ml/gal of molasses, that was a mistake, turned my res and root ball into goop, ruined airstones. I think if I wouldn't have caught it it would have killed the plant. I used way too much molasses. 1ml/gal would have been better I think.