The line you used is just fine for the Soyokaze (Gentle Breeze) 31, but you might also want to know that the rod will handle a furled line as well. You might give one a try if you care to throw a bug or two, or anything else heavier than the nymphs you were using. The furled line that works well for me on Gentle Breeze is an 11 ft. Bushi from Moonlit Leaders (the Bushi floats well, with flotant).

Since you appear to be fishing on still water, you might experiment to find out the max length of line you can effectively throw. Try adding some Amnesia (I use 15 lb.) between your line and your tippet, three or five feet of it.

My other favorite rod is a Sagiri, and it has much the same feel as Gentle Breeze although the Sagiri is a bit longer.

You will be surprised by the large size fish your Gentle Breeze will handle, but do obey the Light Tippet rule to protect that little rod. I use 4 lb. mono Stren spinning line.

I love my Gentle Breeze and I think you may grow equally fond of yours. Have fun.

~Paul