Thanks, we go the extra mile to keep people happy.
The best thing that you can do for your stoker is to fill it once and never add water again. In the real world, that means fix any tiny leak immediately. Check especially around the coil gasket. You can develop a leak there and never even know, as the water will evaporate quickly. Coil patch plates are available for stokers which have had leaks and won't seal anymore.
Introducing fresh water into a boiler because of a leak is a quick way to rust it out.