I have only been growing for nearly 7 years now and the only ph pen I have ever used is the cheap and cheerful 1 that cost me £4.99 from ebay, I renew it every year or so. and I always and I mean always produce top quality smoke from it at ph 6.5 in soil. You know the saying... if it aint broke don't fix it lol. It seems to work for me, like natureboy said, I'm not gonna argue with anyone on here about it either. Got more important things to do like rolling a doobie

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My last crop and my cheap and cheerful ph pen