Those caught my eye at a Petco the other day and I looked at the specs ont he box as well as for the expansions. For the flow rate they give you, they seem to really overrate the pump it seemed to me. Also, when I looked a the ratings for the expansion, it showed the flow going up, which seems counterintuitive to me. If it's the same pump pushing water through more media, I would think the flow would actually drop. Do the expansions have some kind of booster pump in them to keep the flow up?
It is a violation of federal law to use this product in a manner inconsistent with its labelling.