Test kits Pond vs Fresh water

[scotch]

I recently read a thread where it stated that a pond ph test kit would expire before a fresh water ph test kit would, anyone know why? Also will there be a difference in results between the two for PH, Nitrite, Ammonia, Nitrate?

 

[Fishguy2727]

That doesn't sound right. All the kits are the same except that master pond kits will come with a liquid salt kit.