I've inherited a cooling tower made by CCT of Texas. It was built in 1993 and hasn't had any maintenance done since installation. I had the chance to crawl around in this pig to look it over and found large amounts of scale built up everywhere,distribution piping,walls and fill media. Once cooling is no longer needed I will be shutting it down to do repairs and cleaning. The fill media is about 5 feet deep with the bottom layer being ceramic block.

What would be the best way of cleaning the fill media?

I'm afraid just spraying something on isn't gonna do anything for the layers underneath.

What cleaner would you guys recommend?

I need to use something environmentally friendly since this will eventually be pumped out onto the ground.

Any help is greatly appreciated.