I can explain the ammonia ....
0.5 of ammonia is not much & can easily be test error. Also, chloramines (disinfectant in tap water) breaks down to ammonia+chlorine with any dechlor ... those are bound & harmless, but will read positive (like 0.5) in a salicylate test (like the FW
API). So I wouldn't worry too much about the ammonia. <To prove it to yourself ... mix Prime with plain tap water & test for ammonia .... If you really need to test for free ammonia, buy a Nessler kit (Salt water ammonia - 2 reagent bottles) ... but it really is not necessary>
The nitrites coming down from 1 to 0.25 is just right for a 80% pwc
I have no idea what is happening to the pH or nitrates ... something is off in your fridge filter??
To be safe, you need to parameter match the water with a big pwc
like 80% .... That means testing the change water against the tank water BEFORE you put it in .... If the parameters are off, you need to do a series of smaller pwc
's, or put the change water in slowly ... like over 1/2 hr+ so the fish can adjust. <The cory prob got a bit shocked with the para change but had now adjusted.>