On the last pool on the signature (a smaller pool), I found this white marks, but can't tell what they could be...
Do the pictures help you identify what could it be? and how to remove them? These white things are located on the edge of the spa... also in the pool ground there are some white stuff... looks like bird poop... but the white ones on the edge are hard to get off..
Brushed them a couple of times already but there is very little improvement..