Would like to point out that this was not caused to a PH Balance, but a suspected reaction with my aluminium radiator.
Was a balls-ache at first, numerous cleans of the blocks and fittings and new pipe installs.
Though I wasn't overly impressed with the PH reasoning at first Mike had helped me throughout with replacement coolants, (more pastel, and then his water + dyes), pro cleaning kits, replacement pipe (rebuilt like 4-5 times!) - Hell, he even tried to send me a replacement radiator.
He went above and beyond for me.
His responses have sometimes be perceived as blunt on the boards, but in reality - hes a cracking chap and his advice is concise.