yes like squid said, you need to test the waters ph, and to test the runoff, you need to water enough to cause the pot to saturate, with about 10% runoff. When it runs out of the pot, have it run into something like a bucket, and you can put a ph strip or digital ph tester in the runoff water. Needs to be around 6.5. When you test your water going into the pot, it needs to be the same. To raise your water's ph, you can use baking soda. To lower it, you can use apple cider vinegar. I just used the vinegar and it works awesome. just a couple drops to a gallon of water and you should be good(depending on what your waters ph is reading). If a newbee is ever asking questions on this site about how to grow, youll always hear muddy or anyone thats good at it say that ph of water and soil is the most important thing to monitor when it comes to MMJ. If you want a good grow, definately take that advice, and everything will be just fine. Almost every problem that plants have when it comes to burning/nute lockout is directly due to ph. So if you dont have nothing to test with, GET ONE! (im not yelling, just want to make sure you know the importance)