I did not buy my ferts from Tom. I buy them from aquarium fertilizer .com. Which I think deal with Tom. I am not sure about the expiration date on the fertilizers. I have to check the bags they came in. Can you tell me about how long they are good for? Also how long do they last when mixed in the fridge & some of the fertilizers get hard when placed in the fridge, but moldy when not chilled. Dry ferts still the only way to go!