Sure. The G10 is like most small sensor cameras - it does not have a large dynamic range. Dynamic range (for in case you did not know this) is the largest difference in dark and light areas that can be captured on the sensor. If it is limited like in this camera, it means if you do not underexpose the shadows the highlights will most probably clip (blow out - i.e. loss of detail in the highlights) in a typically lit tank.

This is from practical experience trying to photograph my tanks using a variety of cameras. My Canon 1Ds Mark III has a very large dynamic range, meaning I can take a photo of the tank and adjust it in Lightroom afterwards and pull back the blown highlights and boost the shadows to get a more pleasing photo. With the G10 I could not do that - if I take a photo of the tank the tops of the live rock is always blown out beyond recovery. So what I used to do is to expose for the highlights (i.e. make sure the histogram moves to the left and is not bunched up on the right hand side). This way I do not blow the highlights and I get a more pleasing photo.