As far as harvesting goes and if you want to flush that's up to you I wouldn't feed so heavy at the end though. IMO if you're getting any salt build up I would flush it. When I was doing hydro I did flush for the last few waterings a week maybe two because I don't like all the chlorophyll. I switched to organics and make my own soil now, so I don't have to do any of the things we're talking about anymore. I still get that yellow look at the end though, natural life cycle. The purple in this is because of 40 degree nights. overall I think your plants look great and you're doing a good job.
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