Dumb question - PH

I have some PH strips here, they're the dual window variety 'for saliva and urine' when I test my CM on them they don't change colour (reading 4.5)There is enough CM on them so I know that isn't the issue and they do change colour when other things are on them, so does that mean my PH is already low?
Or are these not appropriate for CM? Also - I thought all cm was alkaline, I do have a lot around my fertile window (sorry TMI) so am I to assume its acidic (I'm fairly sure I read that it's alkaline tho?)

No, those are the right strips, your pH goes up around ovulation. So if you have some vaginal discharge at earlier or later parts of your cycle it is often acidic but will rise around O.

Some people have low ionic strength too and cant use ph strips.. maybe that's the issue?

Yeah, that can supposedly be an issue for some people. But I do want to point out that we've never seen any benefit from testing pH anyway (soooo many pH opposites going all directions that I cannot believe that it is telling us anything of value any more) and additionaly the stuff that is supposed to cure the "low ionic strength" issue as recommended by IG is VERY dangerous and not recommended by me or anyone else. If you do have low ionic strength you need a digital tester or to give up on testing pH!