Going from 90 to 120 gallon tank do I use my current sand bed as is? Do I clean it then put it back in? Or just toss it and buy new? Current substrate is not sand I think it's crushed shells only about an 1" deep. I do have a deep sand bed in a 30 gallon fug that it will not be touching, hooking into new tank.
Thx
Thx



