The TF-100 has the FAS-DPD and is the best value as it has larger bottle of each of the reagents... and comes in an easier to manage box.
I store my test kit inside the house. I test my FC withe the OTO or the FAS_DPD nearly everyday. I use the OTO for most days if the FC is expected to be in the 0-5ppm range and use the FAS_DPD when I am doing my weekly full test or if I think the FC is greater than 5PPM. The TF will last at least one season. I am on my second season and I only running lowish on my CYA test solution (the big 8 oz bottle).
I store my test kit inside the house. I test my FC withe the OTO or the FAS_DPD nearly everyday. I use the OTO for most days if the FC is expected to be in the 0-5ppm range and use the FAS_DPD when I am doing my weekly full test or if I think the FC is greater than 5PPM. The TF will last at least one season. I am on my second season and I only running lowish on my CYA test solution (the big 8 oz bottle).