There wasn't really a complaint as such Andy, the whole point of my recent "experience" was lowering the fertiliser dosage to see what happened. Gsa appeared on some plant leaves, which was the reason why I posted in this thread.From the pictures the plants and fish all look fine to me. Is the complaint about GSA on the back glass (it's hard to tell in the photo)? If so, I'd scrape that down and do a water change and declare victory really.
Having said that there's always room for improvement. 🙂