If you have the room, I would give it more time. I had 2 that I messed up (soil) and one of them is now some how out growing my others. And the other one is trying to catch up. Gives you something to learn from for sure.
As for the brown on the siding, whats your ph levels been like? Water Temp? And how often are you givng them cal/mag? I could be wrong, but I think it might mag issue.