1). Make sure you have a few bio balls in the goose neck (these bio balls help chop water into foams.

2). Connect the pump (or one of the "T" outlet from the main pump) with a flexible hose to the inlet (the larger gray barb elbow) on top of the goose neck shape tube of the skimmer. The small black elbow on the goose neck is for ventilation purpose and you don't need to connect it with anything.

3). Turn on the pump (or slowly open the ball valve) to drive water into skimmer through the goose neck.

4). Slide gate located on middle of the black box up and down to adjust water flow - if you see water level raise more than 2" above the black square box, you slide the gate up to allow more water pass so the water level in the tower comes down allowing more room for foams to accumulate and eventually reach top and deposit into the waste cup. The proper range of water level when running is within 2" from the top of the square box. If it goes higher or lower, you use the slide valve to adjust water flow.

5). The black elbow on the waste cup (the large cylinder container on top of the tower) can be turned up or down - most people use a flexible hose to connect it to an additional waste container so that the dirty waste will not overflow back into the sump when it's full, although you can cap it or turn it up and take the cup out and empty by hand.

6). Generally, it takes 3 to 7 days to fill up the waste cup - if it's full too soon, you adjust either the ball valve or the sliding gate to make the water level in tower lower, if it take more than 7 days to fill up the foams, you adjust it so the water level in the tower higher. It usually takes a couple of times set it right. Once it's set properly it can go for months without having to reset, and it does an amazing job for your reef tank.