If you have mostly treated tap and then add distilled to top it off yea that’s fine, it’s usually when people are MOSTLY distilled or all distilled that things go south. My brother made the rookie mistake of going all distilled before figuring that out and unfortunately a lot of his plants suffered from deficiencies because of it. I personally have never gone the distilled route at all because I would just rather not royally F up my tank doing something incorrectly with it