i use normal tap water, no algae at all in it (i have a silver chain in the res as im told that keeps it at bay?)
Although i lose 2-3 litres per week to evap

With that sort of evaporation I would position the res under a tap

i use normal tap water, no algae at all in it (i have a silver chain in the res as im told that keeps it at bay?)
Although i lose 2-3 litres per week to evap


Right i went to halfords and they said they don't sell a Halfords Coolant Conditioner ?
Anti-freeze will do I suppose.Silver kill coil or 2 drops of PT nuke.
For PT Nuke, would that be for the whole loop or per litre?