Glad to hear that your going sand. You have another issue with the UG filter to deal with. Can you take that out if you move the Cc over to one side of the tank? As stated above remove in sections allowing the new sand bed time to build up bacteria. if you had more LR
this would not be as big of an issue. Seeing you have little lr
you need to do this slowly and in steps. Are You getting LS
or play sand? If you just dump the sand into the tank your going to have a hugh sand storm so you should try using a PVC
pipe and pour the sand into the pipe moving it slowly along the bottom to get the sand spread.