You will need a suitable plastic container a small drill or similar, an "L" shaped uplift, and a 100mm by 12mm overflow pipe.
Place the container at the side of the aquarium.
Drill two holes just slightly higher than the depth of the aquarium.
Push the "L" shaped uplift into one of the holes.
Push the 100mm by 12mm overflow pipe into another hole. The main idea is to create a system where the uplift draws water from the aquarium and empties the water into the container. The container will eventually overflow and water will return back to the aquarium via the overflow pipe.
Fill the container with water from the aquarium.
Start the flow in the uplift and make sure that both the uplift and the overflow pipe work as they should.
Place a lid on the container to keep the temperature stable.
Carry out frequent water changes in your main aquarium to make sure that the water is suitable for sensitive fry. When your fry is big enough to live with the adults, they will already be perfectly adapted to both temperature and water conditions of your main aquarium.
never breed pleco's but i use old fishing line for everything i breed. i just ball it up and fill one side of the tank with it. Or cover the bottom of the tank with it a few inches deep and weight it down in a few spots.