We experimented with several solutions (as we found the tablets expensive and needlessly complex). We tried with our own home-made baking soda solution. It work

We experimented with several solutions (as we found the tablets expensive and needlessly complex). We tried with our own home-made baking soda solution. It worked generally well, except for something like tomato pulp. You'd simply still see it afterwards (red). We gave up after a while, and found a relatively cheap and good brand of tablets. YMMV.