Duke,
The pink timber (H1.2) is not for use below ground level or in wet environments, especially where salt water is involved (Salt water is very good at rotting/rusting our stands ). Next time use a grade H4 in ground and H3 above ground (for external use).
I can see you have already concreted so the best option would be to give the timber a very good coating of external acrylic paint, even then I would be bit concerned for the long term use.