Can I use ph strips from pets mart ?

No reason not to, something is far better than nothing

You could use the strips for testing the pH of what you will put into your medium either regular watering or if your doing a feeding but as far as making sure your soil is at the right pH, it will be handy to have a probe on you to see how it's doing. I do think that you can use the strips for your soil but you have to mix your soil in water I believe and let the soil settle(i would research more on this if that's the case). You can also buy those soil tester kits (think its called rapi-test?) that have the pills for each macronutrient as well and test your soil that way but this process takes longer then if you had a probe. Hope this helped :)

Hello.. Hope all is well.. Yes this will do exactly wot u want.. Bit more ticky on exact accuracy but wit practice u get same results..it will b ok and better than nothing till ur order comes.. Stay safe.. 👍