Chem_Geek, do you know what label Odyessey product is sold under? From their site:
Ultrachlor is also available in drums and totes through Odyssey's re-sellers including the Dumont Company (www.dumontchemicals.com), Bell Chemical (www.bellchem.com), Florida Chemical (www.florida-chemical.com), SPIES (www.spiespool.com) and UNIVAR (www.univarusa.com) in the State of Florida.
Their site also notes:
The Odyssey bulk manufacturing process is unique. Chlor-alkali technology has been used for years to produce chlorine and caustic out of salt and water utilizing an electrolysis process. Odyssey takes this technology one step further by combining it with a Powell continuous bleach plant. Odyssey's process is superior in that it utilizes demineralized water and evaporated salt with membrane cell technology. The result is a much purer grade of caustic and chlorine relatively free from impurities. The resulting chlorine and caustic is taken directly off the cells and combined in a Powell continuous bleach plant to produce a superior quality product. Of the handful of companies who employ this technology around the country, Odyssey’s cell room has been in operation by far the longest.
So, it sounds like commercial bleach is much more often UNfiltered, than filtered.

Without a trustworthy brand label, I don't know of any way for the consumer to know what they're getting. I used to buy truckloads of bleach made by Allied Universal, who is a direct competitor for Univar. I was serviced out of their Ranger, GA plant. But I know that they had plants in Miami and other Florida locations, and did a LOT of pool store deliveries, with UN-filtered bleach. In fact, the way many of the Florida pool stores re-registrations were set up, they could fill their tanks with filtered bleach this week, and then purchase from Allied or another un-filtered producer next week.