On Feb 26, 9:02 am, "TheScullster" wrote:

The question is, will the rest of the water in the system be affected this
way, or is this localised to the header tank?
If it recurrs, the advice on the AF10 bottle was to that the system may need
steralising.
Anyone know what's involved in steralising a CH header tank?

Usually confined to the header tank, I believe. The high temperatures
in the heating flow and return pipes will kill any organisms, but the
temperatures in the F&E tank and the nutrients will encourage the
proliferation of any bugs that get in. I think a scrub out with
bleach, wearing PPE (gloves, goggles, respirator) was recommended.

I had similar problems but switched to a sealed system.