redoing my water cooling system, last time i bought stuff anti freeze was the stuff to get, got a mix of all sorts of metals, and i run a large water tank, so might have 10-20 litres of water all together, is there any suitable stand alone corrosion inhibitors i found one but it wouldnt be cost effective 
Anticorrosive AntiCorro-Fluid 50ml £4.07 for 2.5litres
Anticorrosive AntiCorro-Fluid 50ml £4.07 for 2.5litres