Just an idea I have rolling around my brain... (small space with lots of obstacles)
For my 125G that I am rebuilding. Would it work to have a series (8 or 9) 4" PVC pipes stood side by side along the back of the inside the tank for bio. The idea is to connect them so that water flows in through a series of slots or holes in the first pipe, then out through a connection at the bottom to the second, out through the top into the next, and so on until the flow reaches the filter intake. Fill all the pipes with Bio balls creating an inside the tank bio pre filter. All the pipes would be capped at both ends (removable caps for the tops), and connected with short sections of pipe to allow flow to the next pipe. The pipes would be as tall as the tank, and since the back wall of the tank will be black, the whole setup would be near invisible behind a wall of plants..
For my 125G that I am rebuilding. Would it work to have a series (8 or 9) 4" PVC pipes stood side by side along the back of the inside the tank for bio. The idea is to connect them so that water flows in through a series of slots or holes in the first pipe, then out through a connection at the bottom to the second, out through the top into the next, and so on until the flow reaches the filter intake. Fill all the pipes with Bio balls creating an inside the tank bio pre filter. All the pipes would be capped at both ends (removable caps for the tops), and connected with short sections of pipe to allow flow to the next pipe. The pipes would be as tall as the tank, and since the back wall of the tank will be black, the whole setup would be near invisible behind a wall of plants..