Planting Up a Barrel Pond

A few years ago, I built a half barrel pond and everything was fine for the first couple of years, until I got blanket weed. Unfortunately, it would stick to the pond liner making it impossible to really remove so I decided to start from scratch. I took everything out last year and whatever was left of the blanket weed on the stones/bricks/baskets, should be well and truly dead.

When looking at what to plant this time round, I was watching this video.



The number of plants he used seems more than other recommendations. Would nine be too many?