I recently started to do some hydroponics, I found this at a garage sale is this hydroton http://i.imgur.com/evEMVsq.jpg
It appears to be. Looks dirty. Smash one open and look inside to confirm.
If youÃ¢ÂÂre starting with an Ã¢ÂÂEbb & FlowÃ¢ÂÂ system or with the DTW systems, then Ã¢ÂÂhydrotonÃ¢ÂÂ is the perfect choice for you. Because water flows between them with ease, supplying roots with nutrients and oxygen.