Using the kratky method what is best to use

Clay balls And or anything you have that roots can grip that dont hold moisture too much.

Pool noodle - 2” diameter, slice about 1” and have 48 for $1usd

I used clay balls last year and exceeded expectations.

Both will work about the same for the Kratky method. As far as nutrient solution, I use Masterblend, I am thinking about also trying General Hydroponics brand. I prefer the dry mix so you dont pay to transport water. I believe you can find both on Amazon, but Im not sure what is avaliable in your area. If you can find a hydroponics store, they might be able to help. I have been growing salad greens in a DWC bed with the Masterblend.