It has the eshopps psk-nano rated for 300 gph, 3/4" vinyl tubing and a ball valve closed just a hair to help stop the gurgling noise. I am actually on pushing around 200 gph through it. First chamber has my temp probe Purigan and a grounding probe, second has a heater and third has the over flow in it (go as big as you can, I already had this one on hand) for the return I had to cut the back of the lid a bit and ran 5/8" tubing over the over flow (with a slight bend) and hose clamped it to the included right angle for the return hole (I had to warm the tube with hot water to soften it a bit so I could slide it over the piece). Hopefully that made some sense. If not and my thread doesn't shed anymore light let me know, ill check back tomorrow and snap a few quick pics