I coated my bridge and decking with G4 followed the instructions to the letter 3 coats next one just as the last is going tacky and so on , and yes it looked fantastic , got the photo's some where to prove it ,
lasted for a year may be a bit more but slowly the water got in under it and now its all but gone. Its not as though you can re-paint it on top of the pond or filters and mine is to big to remove so I've let the wood go natural . if you could redo it before it peeled though it would be great.
as for my pergola I used sadolin classic and had no problems , heard from many friends about this sometime ago . and I believe they do black

make sue it dry before putting near the pond just to be safe.
there is also a company something to do with Kasuri who also make pond safe paints .