Green pond water is not advisable, since healthy water should be clear (unless you want some brown tannins from leaves or turf for instance), the green comes from algae. Algae tends to bloom in low oxygen waters, mostly without the precence of waterplants.
It is advisable to use the green pond water to breed daphnia though, just don't let your newts in the green water. Healthy, clear pondwater should be fine. You could also use dechlorinated tapwater. Dechlorinate it by leaving the water in some buckets for 24 hours.