PH level important?

It's incredibly important. If you're water is too far out from the acceptable range the plant will not be able to access vital nutrients. The sweet spot if between 6-6.5. I'm lucky my tap water comes out at 6.5👍🌱

It's good to test and know your in the right range, so test strip or drops are an easy cheap option. Most tap water will be around 7 and once you add nutrients is still in an ok range for a soil grow - but it is good to test and be sure. PH up and down are easy solutions but as others have said iits pH down you usually need and vinegar will do (literally a ml or 2)

don't buy the specific ph-down or up.. it's a waste. a 100-pack of strips that resolve to 0.1pH is good enough to learn your tap and tap+feed pH levels with plenty of leftover to spot check for a couple years, lol. I rarely check it anymore but it is supremely important... pH can cause any and all deficiencies and toxicities on its own. Distilled white vinegar is often around a house. That works well. If you have a pool, you have HCL, a VERY strong acid. Apple cider vinegar is fine with soil and even provides some other useful stuff too. Don't use that with hydro. stick to the distilled white vineager (5%). Usually you don't have to ph-up, but you can find a base and use it. sodium carbonate or the like should be avoided (Na+ is bad), but can be used a more than a couple times safely. Calcium Carbonate, or garden lime, is a better way to go, if you have issues with acidity... you can amend your soil with it to start a grow off.

PH is probably the most important thing. Spend some money on a good tester, most of them will also do EC. PH in the wrong ranges can really kill a grow, don't assume that your tap water is 7 either. Mine in Denver is around 8.8 ph with lots of metals in it.

Yes man! Super important!!! Get yourself a good ph checker. I use one for my soil. It helps rule out other problems you may have later on. Soil should be no higher then 7 and no lower then 5.8. Good luck man!