The only cycle speeding products that will work are the ones that are kept refrigerated and have a shelf life. Bacteria can't live indefinitely. They must be refrigerated too. Any product that travels by truck, sits in warehouses and on shelves has probably seen temperatures of well over 100 degrees for long periods. Can you imagine this stuff traveling by truck for 400 to 500 miles through the mid-west in the dead of summer? Temps of 110 plus and then add another 50° or more to that for being in an unrefrigerated truck. Of all the products I have heard about, Bio Spira seems to be the only one that works and it only works if it has been properly handled and refrigerated. I haven't tried it personally but everything I have read leads me to believe it works. I will try it on my next tank.