I think the question is hypothetical as he is researching the subject but hasn't got a setup running?
Generally if you have a bucket of water and you add nutrients, it will stay at a certain ppm and ph. If you add more nutrients the ppm goes up, if you add ph down the ph will go down but apart from that if the water stays untouched so should the ppm and ph.
If you were to actually grow plants then fluctuations don't mean that much, if you pay real close attention it can give you an idea of what is going on ie if the plants want more or less nutrients but generally for any beginner grower I would suggest you monitor the ppm and ph and adjust it when needed to keep it in the right range, never mind what it means, just adjust and keep the plants happy.