I recently purchased 2 of the 100 ml pre-bagged products. I was going to use one and have one for backup because you can recharge the stuff. I am using the c360 marineland canister filter and the bag is too small for the tray. I was thinking about throwing both of them in there. With both it will pretty much cover the entire tray. I guess what I am asking is can u use to much or will it just maybe extend the use before recharge is necessary. Can too much be bad?