Can you use liquid chlorine with a de filter?
Yep, I use it all the time, and have had no problems. FYI, "Liquid Chlorine" is Sodium Hypochlorite. Next time you're in the grocery store, check a bottle of Clorox ultra bleach's ingredients. Sodium Hypochlorite, right? 6%? Yep! Same stuff. Clorox even has a guide on their website on how to use bleach as a Chlorine source for a pool.
There is a big difference between Clorox bleach and swimming pool chlorine. Swimming pool chlorine comes in either 12% or 10% strength. This is what you should be using. To use the weaker product with other inert ingredients is costing you many more dollars than you think. For one, you will have to use triple or quadruple the amounts of the 6% to accomplish the same job. There are no or little inert ingredients in "good" chlorine. There are over 94% of other ingredients in Clorox that you probably do not want introduced to your pool water. However, it can be used in a pinch. Your health depends on using quality products.