Absolutely. Purity is often stated in important ways. One way is by grade. Food grade, pharmaceutical grade (both good), technical grade (often not a good one), reagent grade (good), etc. Those specification are not just % purity, but have specific tests for specific possible impurities.
The one you linked says it is food grade (in text, not on the package, that one might be wrong) and 99.95% pure. Both are good for our purposes. It also says on the package that it meets water treatment standards (water chemical codex) which is also good.
oddly, 99.95% is way more reassurance of purity than is 100%, which is not a stated purity of a chemical supplied by a chemical company. Such companies would have 95%, 99%, 99.99%. Not 100%, which is more like an ingredient list on a consumer material.