What mistakes did you make, or what do you wish you'd know, when creating your wildlife pond?

[Trustytoo]

Hoping to have a wildlife pond in place by October to attract and help creatures and birds. Plan is for it to be approx 6 feet by 3 feet in an oval shape.

40cm deep is what I see recommend and with a wide shallow ledge all around where plants can sit. Going for an EPDM liner. With builders sand under it? Don't have any old carpet.

Have watched lots of YouTube videos but each one says something slightly different.

Would like to hear from anyone who has been through the process and can share knowledge or tips.

We have put in a lot of aquatic snails which are multiplying quite quickly, the water is clear and practically no algae so they're doing their job well. We only have a small pond as its a small garden, but we love it. Got a solar floating fountain which keeps some movement in the water.

I should never have planted mace reed in my pond.