I Remove the Quiet[]. When something is not working we want to see all warnings.
That shows there is a 1/0 problem that should be tracked down and fixed.
Next there are warnings about inexact, but I think those can be ignored.
Next it prints "Hola Null"
That goes away if I change Print["Hola ",x;]; to Print["Hola ",x];
But then it only prints "Hola x"
You print "pHcalc { Log[H$257549]/Log[10],..." and that is possibly an
an issue related to local variables inside of a Module.
If I remove the use of Module then the H$257549 are replaced with H.
Next there are lots of errors about "not a number" when x is negative.
Those need to be tracked down and fixed.
Can you reproduce all those warnings and errors?
Can you see the reason for any of those and perhaps see a way to fix one or more of those?
