I also run drip clean in a drip to waste setup using rockwool. I drip to 1% to 2% runoff. Basically the only reason I runoff at all is to ensure the rockwool is saturated. Drip clean is some amazing stuff. It removes the need to flush during the grow, it saves tons of money because you use less nutes, it's so simple. I still flush for 10-14 days before I harvest though. Not for salt buildup, but to clear nutes out of the plant.