Yes, I agree with the last 2 posts-JonMon and Mark. You WILL have to strip whatever is on your deck currently. My goal in life is to work with wood products that don't have to ever be stripped. We are still stripping the exterior of our clapboard house that has 130 years of peeling paint build up. That is how we came to learn about Allback Paint. Linseed paint has been used for hundreds of years. If you ever tour Mt Vernon, President George Washington used it. However, the new products are greatly improved by purification process. Linseed products protects and nourishes the wood and leaves it breathable so there is never trapped moisture and a plastic coat to peel. The draw back is the slower dry time. There are no chemical accelerators. This fact makes the product "GREEN" for the environment. Hot dry days are a perfect time for painting Boiled Linseed. To find out more about Purified Boiled Linseed try the link posted or call Soren or Collete at Viking Sales. They have been most helpful to me. Be sure to ask them if your climate will allow the Boiled Linseed products to cure properly. I live in the mid-central states. We had 30 days of 100 degree weather this year. I am still researching Floor Shield USA and Lifeline Endure at 1-800-548-3554. If I cannot find a longer lasting product that doesn't need stripping to re-coat than the AllBack products, I will definitely be using the Linseed Varnish mentioned in the link. Strip a deck once and you're desperate to never do it again. Here is a link that might be useful: Silent Paint Remover and Allback Paint

deck All wood is pressure treated

Semi-transparent stain generally isn't very durable as deck stain. It's most often used for vertical surfaces. It also isn't very long lasting on sunny surfaces. If you are going to stain the deck, your best bet may be deck stain!

I would have left the entire deck light and natural, let it complement the mortar and fit with the natural outdoor environment, but since you have already stained the top rail you may be stuck with staining the entire deck. I would start with stripping the stain from the top rail and see how it impacted the color. Then I would re-stain with something that has a more natural feel, (Walnut, Chestnut)