There was an idea to have an option to set the starting points and the bonus value during the pond definition.
Anyway, it should be assured that no future pond game becomes unbalanced because of badly chosen parameters (e.g. starting with 50 points and bonus 5000). That's why this proposal has been created:

x = starting points (multiple of 40)
x/40 = bonus

The current parameters (20000, 500) follow this rule as well.