I have recently stopped using any kind of pink toilet flush, it causes gunge.
I have tried the bio washing capsules, I did not find any problems but also did not find any advantages, I did not persevere with them to draw any meaningful conclusions, sorry.
I am now trying a couple of squirts of washing up liquid in the flush reservoir, no pretty colour, no nice scent, but it seems to be effective as a rinse agent, early days, but I will be using washing up liquid until I find something better.
My view is that the qualityperformance of the bowl sanitiser additive is the most important factor, right now I am using the Aldi product with acceptable results.