Plumb a single overflow to two zones

A tank with a single overflow can still run to two zones of a sump.  I recommend running the drainline into both the skimmer section and the refugium zone, and I'm often asked how this is accomplished.  Using gravity and a few extra fittings, you can direct water to two different zones from a single drain pipe.

I was able to demonstrate this configuration in my booth at MACNA 2012.  These images capture the method, using a tee fitting, some elbows and a ball valve.  Initial plumbing will take an extra 20 minutes of your time but lasts the lifespan of your setup until you opt to upgrade.

Installing the Aquahub ATO kit

With the new set up, I've tried to avoid holding anything back and went "all in" so to speak. So I got busy one night, wiring up this ultra safe system by Aquahub. The way it works: You have two float switches wired in series, which are powered with a 12v DC power supply. When the switches are down, a relay opens the flow to a 110v power cord to supply power a pump that can push top off water from a reservoir into the sump. As the water level rises, the float rises and cuts power to the relay, which stops power to the 110v cord shutting off the feed pump. If one float fails, the second one is a back up to make sure power is cut to the feed pump.

How to Prime a HOB overflow

A HOB (Hang On Back) overflow or weir is a device used to drain water from the aquarium safely into a sump.

You need to prepare yourself, as this is about 30 seconds of your life that will get your heart beating faster than you'd expect.

  • Get a piece of flexible airline tubing, about 30" long.
  • Get a large cup filled with RO or tank water.
  • Get a second person to be in charge of turning the pump off if needed.


Thread the piece of tubing into your overflow box so that the end is at the top (apex) of your U-tube (or U chamber if you have a wier). The other end goes in your mouth.

Have your assistant turn on the return pump. Water from your sump will pour into your tank and the water level will rise. Do NOT panic, you have about 30 seconds to do the following, which is plenty of time.

DIY Overflow Box

General Overview


You need to break out the Yellow Pages and look up "plastics"... call one up that seems near you, and ask if they sell AcryLite to the public. Most do. You want acrylic, not plexiglas - the stuff Home Depot sells. Plexiglas ages, turns yellow, gets brittle, and cracks. Acrylic is harder, and you can buy various thicknesses.

For an overflow box, 1/8" is ideal. I built mine out of clear acrylic, and I can see if any problems develop and make sure all is well. Being clear, I see when a fish or a crab or a snail climbs in (all three have), and I've seen copepods walking around in there (which was cool). The BAD thing is that it loves to grow algae in it, and it is rather annoying to clean out. I clean it about once a month, and pull out some thick matted hair algae that definitely restricts the flow.

Building a Closed Loop (German)

Ein Closed-Loop-System für ein Becken ohne Bohrungen  

English version here:

Ich wollte ein Closed-Loop-System an meinem ungebohrten 110l-Becken betreiben. Mein Ziel war, einen SCWD Strömungsverteiler zu verwenden und damit zwei MaxiJet 1200 Strömungspumpen zu ersetzen. So wurde er verrohrt...

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