Question: How do I force simplification of products of square roots of positive integers

In an atomic physics calculation involving the quantum theory of angular momentum, there appear polynomials whose coefficients involve square roots of positive integers, for example

sqrt(6)-sqrt(2)*sqrt(3) 

Maple does not cancel such an expression to zero because the code allows for the possibility that a square root can be positive or negative.  In the physics context all these square roots are positive.  Is there some simple way to induce Maple to cancel such expressions by enforcing an assumption that the square roots of all integers are positive?

More generally, again making the assumption that all square roots of integers are positive, is there a simple way to to standarize products of square roots of positive integers, like

sqrt(2)*sqrt(3)*sqrt(5)*sqrt(7), or  sqrt(6)*sqrt(35), or sqrt(10)*sqrt(21)

to a standard sqrt(210)?