I was speaking to a man who was repairing my split shower wall, and he said that detergent based cleaners would be likely to cause chemical damage to the plastic used for shower trays etc. He recommended using CIF cream cleaner and don't worry if you feel that it is "gritty": he said that it does the job well.
Incidentally, I was interested to find that he often converts 'wall-board' lined showers to sealed plastic walls. I don't in any way wish to be considered to be advertising, but I was really impressed with his work and the services which he provides (mainly warranty work for all of the major van makers)
Maybe the moderators could post whether it would be ok fo me to post the web address of his company?
Regards to all