hi there, i don't know what clearex is. my opinion is when you decide to start your flush, then just change to ph adjusted water and let all the nutes be flushed out that way. no need for any other additives. it is just like in autumn when the plants are done with their cycle, it tends to rain alot, in turn, flushing the plant. plus it is cheaper and you won't have to add anything to it. just flush away and enjoy!!!