One was the water-chemistry group that took the temperature and pH balance of the pond water to test for alkalinity and the presence of nitrates and phosphates.
(One; was; the water-chemistry group that took the temperature and pH balance of the pond water) (the water-chemistry group; took; the temperature and pH balance of the pond water)
One the water-chemistry group
was took
the water-chemistry group that took the temperature and pH balance of the pond water
the temperature and pH balance of the pond water