I have used them previously. As I am I liked that they were Canadian. I was using distilled water at the time and a bit different medium but I have had no issues and everyone I know that used them had success. That being said I went with green planet nutrients and the medi one line because it was organic and I really like the results comparably and the smoke even with me botching some things and not adjusting for lesser quality water. I felt Grotek was good though and I wouldn't not recommend them and I remember them being priced well