No, but I would advice using anything other than petco's sand.. it's not actually sand, and it's not inert, it's a manmade gravel and will raise your pH. Any of Caribsea's "sands" are fine and come in similarly sized bags.. 5lbs is all you'd need for a 4gal tank.
Is that right? I've never had a problem related to their sand, I really think this is non issue. It's not the only substrate to buffer the water in some way, if it even does at all...
I give my fish coffee