Hi Mark, We promote a step back mopping system which is ideal for cleaning polished porcelain tiles, we use waffle microfiber floor cloths which are far more effective than traditional type microfiber mop pads and can be used with just water to maintain porcelain tiles. for deep cleaning grout lines we recommend a heavy duty degreaser which is non-caustic and non-corrosive, dilute the solution 5-1 then scrub the grout lines with your grout brush, give me a call if you want Mark let me know what you are using and i will be happy to gives you more info.