Luckily today the cooling tower water condition is improved. I can see the water quality geting better and clearer. Thanks to some aggressive blowdown and extra backwash via the sand filter. The early detection of which heat exchanger contaminated the cooling system helped a lot in hindering the leaking soya bean oil. That heat exchanger has already been straight away quarantined and dismantled. Just now, the plates were immersed in hot caustic to clean and remove scale sticking on it. Tomorrow, gasket will be clipped onto the plates and the heat exchanger will be re-install. Hopefully, the heat exchanger will be ok and would not leak internally or externally. I also hope by Saturday, the cooling tower water quality will be alright.