Not Pasco but Polk.
Near Lakeland...
Check "Nolan's Aquarium Superstore". (check google or yahoo). Its on 92 on the east side of Lakeland. Awsome place, and has LiveRock for $5.99 Baserock for $2.99 special rock for between $10.99 and $14.99. An amazing collection of healthy fish, snails, anenomies and corrals (even seahorses and octopus if your that way inclined). Knowlegeable staff and a freaking kickbutt aquarium selection.