Unglazed ceramic tile

Any ideas on how to clean and maintain my shower floor? The tile is unglazed ceramic…keep getting these crusty white stains. Here is what I’ve tried with no luck:

• scrubbing bubbles (spray and foam)
• vim with scrub brush
• dawn dish soap with scrub brush
• Lysol bathroom cleaner with sponge
• Method bathroom cleaner
• warm water/hydrogen peroxide (1:1) with sponge