The only reason I try and stress the whole PH tester thing is because alot of Begginers think that having spots, burns,and miscolored leaves has to be a nutrient deficiency or toxicity. If the plant is not at the right ph, 6.5-7 for soil, some nutrients will be taken in at different rates(and some not at all), creating toxicites/defiencies that cannot be treated with fertalizer or anything else excepting for correcting the PH. Bascially what im saying is that if your having a problem with your plants the FIRST thing i would do is test the PH because alot of problems stem from that.