ph question with bubbleponic grow

I am doing a bubbleponic grow for the first time and i am having problems with a few of the leaves...some are turning yellow and dying now im thinking that its just the original leaves dying off from shock because they were clones i used, but im just being cautious of my ph levels, is there any way i can test it without buying the expensive reader, not that i cant afford it i just cant get one quick enough to save my plants if it is the ph level, i was thinking of maybe a pool water tester kit

anyone has any similar problems?
simple solutions

you could use a pool kit but due to color chart reading I recommend a meter thats accurate, but atleast u will have an idea.. i use the ph strips for soil all the time and i just keep in mind that they can fluctuate .5 either way. remember u want ur ph round5.5-6