Ok, if you didnt have any live animals in the tank even after 2 weeks, the tank will not be cycled. You have to alive products in the tank to produce the bacteria to cause the tank to cycle. So just dont be surprised if your water readings sky rocket, it means that your tank is cycling and you will have to do 20% water change every day till your readings are back to zero. I had my 2 axies in the tank while it cycled, very stressfull for me and my axies, but they weathered it just fine.
As for the sand bottom, they will eat some of it but they can pass sand very easily. I had sand in mine but when I got them a 55 gallon tank, it was just easier to keep the bottom of the tank clean having a bare bottom, so I didnt put sand in it. Took them a few days to get used to the bare bottom tank, but they are doing just fine now.
What kind of test kit do you have to check water readings? Do NOT get the strips, they are not reliable. Get the test tube type.