I see Felixxx's point with the old water. But I would use it. It is only half tank of the 180.
and the daily water changes will sort that out.
and the daily water changes will sort that out.
felixxx;4714296; said:it wont solve anything per se but might give you a second reading. although if your tap tests 0 and your tank tests 2 then the test is almost certainly functioning. as miguel says if you can keep up with 50% daily you should be able to deal with most fishkeeping problems