I agree, the water isn't good, expecially in the 3th image. All the water materials with real settings I used (self made or from Thea Library) was too reflective and the water surface was too blue. This is a particular pool with a cobbles surface completely white and my client didn't like the blue color on it. Anyway, you're right, isn't so good to see.
@Rombout: I used XSI only for base modeling. All the scene composition and materials are made in Thea Studio. After the render I add some post, nothing special, just a little tone and curve correction, a bit of vignetting and no more. The images are a bit blurred due to a noise reduction filter I used, because there are too noise after 40 minutes of cooking.
Here is a comparison between original-retouched image: