I agree with other's regarding probable bacteria bloom if all filter's /material was cleaned at once,,or under tapwater that may contain chlorine.
Sand substrates make cleanup with vaccum easy, but some make the mistake of poking /sifting the sand before vaccuming which can result in that which we wish to remove,,,getting buried in the sand.
Is best in my view to vaccum first,,then sift the sand if you feel you must.
Between cleaning of all filter's /material,and sand or any other substrate for that matter in one go,,bacteria bloom is probable.
I try not to get too aggressive at one time with regard's to cleaning.
Maybe alternate between cleaning filter's one one week,,then the other the following week,then clean the substrate the next week,etc.Not so easy to remove too much good bacteria this way.