I've got some young plants here that aren't doing so well. They're about 4 weeks old and look to me to be nitrogen deficient but I don't think that's the problem. I'm using the same soil I always use and this has never been a problem before. I don't usually start giving them nutes for another 3 or 4 weeks. I'm using the pills to check ph and that looks to be somewhere between 6.5 and 7. Any thoughts would be much appreciated. Thanks.