Here are UK Cast Iron Radiators we recommend that you use an Inhibitor in your Cast Iron Radiators.

Your plumber will best advise on what amount and which one you need, but it something that you should mention to him.

Quality Buildcert approved inhibitors protect against the damaging effects of corrosion and limescale to maintain the energy efficiency of the boiler and extend system life. An efficient system minimises fuel bills and reduces carbon emissions.

Two of the brand leaders that we would recommend are

Fernox
www.fernox.com/fernox+home

Sentinel
www.sentinel-solutions.net/