Using pens with acidic ink could literally burn the photos on the pages of your scrapbook. Such pens with highly acidic ink are felt-tip pens. It would be better to use Stabilo markers. This is because these markers don't have any acidic ink content. Plus, these markers usually come in different colors, thus it would provide you with enough room for creativity. After all, designing the photos on the pages of your scrapbook with text markings could do wonders on the total design and layout of your scrapbook.