Originally Posted by Salttanker
he manufacturer would be a good source to speak with about this one
That's usually a good place to start. It really depends on what your testing and who makes it. Many test kits can cross over between FW
but don't assume so without verification. Check the label as well, some will say outright.
Nitrate and nitrite are usually safe in most cases. pH and ammonia are main ones that may not be suitable for both.