+1 for SEBpro PL. I also have been dosing my defoamer slightly diluted onto the top of the mash with a pump sprayer if it's foaming during the cook. It's also easier to knock down foaming in the fermenter with a sprayer.
Its not the buckets. yellow tinge could be caused by iron oxide in small amounts or you could be having evaporative loss concentrating non-alcohols in the product to the point that the color changes. your condenser may have welds that need to be re-passivated