The pH of a solution is a measure of the concentration of hydrogen ions in the solution. A solution with a high number of hydrogen ions is acidic and has a low pH value. A solution with a high number of hydroxide ions is basic and has a high pH value. The pH scale ranges from 0 to 14, with a pH of 7 being neutral.
No, or at least not yet. there small and dont do much improvment. If they were much bigger and sucked better, including some touch-ups here and there, they would have a bigger effect on removing sea urchins.