Wonder if any1 has encountered this before or have any suggestions.

Problem I have is that the Blue antifreeze looses its colour i.e. the 40/60 mix turns clear????

Radiator & expansion bottles are at correct levels. No obvious leeks, level is dropping but only about an inch every 3/4 months.Which aint drastic.
Engine is definitely not overheating as temp guage is A ok.

I flushed the system out about a month ago & used a different manufacture antifreeze to try resolve.Same problem a month later.
Did notice when i was flushing the cooling system that the water was slightly brown,presume this is from some rust somewhere.
I did replace the radiator myself about a year and a half ago due to a stone piercing a hole in the original. straight forrward job, dont think i messed anything there.

Any ideas would be much appreciated. Could a slight leak or water pump cause such an issue?

never come across that one, tho my car is currently loosing about an inch every 3 or 4 weeks - Mazda diagnosed that the waterpump itself is leaking ... not a cheap fix.