sump refugium design

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Aquarium Advice Apprentice
Apr 2, 2007
Seattle, WA
Getting ready to build my first sump and I wanted some quick advice.

I'm building it with a 29 g glass and just siliconing in glass baffles. The dimensions are: 18" tall, 30" long, and 12" deep.

I have an overflow box that uses two "U" shaped siphon tubes draining into a center chamber that then overflows into two separate drain tubes.

I would like to have my return chamber for the sump in the center of the sump and drain one of the drain tubes to each side. So basically the sump fill fill at the outer two chambers and flow to the center where it gets pumped back to the tank.

On one side of the sump I'll house my skimmer. And on the other side I'd like to have the drain feed into a tall camber of LR rubble before it over flows into a refugium and eventually over another baffle into the return chamber.

I hope I painted a decent picture of my plans without confusing everyone. So here's a few questions:

1. Do I have to worry about balancing my flow and drain rates or will my overflow box automatically siphon water at the same rate that my pump returns it?

2. What concerns do I have with power outages and flooding?

3. How can I maximize flow over and exposure to my LR Rubble? Can I run my drain tube all the way to the bottom of the chamber forcing it to rise through the chamber and spill over the baffle into the next? or does the drain tube have to drain into the top of any chamber? My concern here is that the if the water drains into the top of the chamber-it will then spill right over without mixing with the rest of the water in the chamber or recieving the benefits of the LR.

Thank you all for your time...I hope I haven't been too confusing

I will take a stab at this one from the perspective of somebody that has just gotten started in the sw world and has built one sump so far.

1) It seems that the higher the water level in the tank the faster the siphon will perform. There is a limit to this of course. I use a skimmer in my tank and have found it necessary to adjust the discharge of the return pump to balance out the flow or the tank would over flow.

2) Two things come to mind about power outages. When you lose power (not if) the return pump will stop and depending on your configuration will start to siphon water from your display tank to the sump. The two ways to stop this I have found is a check valve or positioning your return near the top of the water so that it can siphon as little water as possible before breaking the siphon. On your siphon tubes the same thing will happen, water will continue to siphon from the display tank until they lose suction. It's critical that you make sure your sump has the head space to handle this excess water.

2a)The other problem that I can see is what happens when the power comes back on. When power is restored. your pump will begin returning water to the main tank. The problem is that if your siphon tubes have lost their prime, they will not be able to take the excess water from the display tank to the sump. in a short time your display tank could overflow. One way to avoid this is to make sure the siphon tube extends lower in the collection box than the drain line. There is some helpful information here.

3) I think you are right about your concern over short circuiting your sump. It seems that most people run the drain lines all the way to or near the bottom of the sump. Some will even build a box with holes near the bottom and fill it with rubble so that the water has to make it's way through the rubble to get out through the bottom of the sump. The rubble also helps break up those pesky bubbles, and trust me there will be bubbles.

And of course a great site for info on building your own stuff is

Hope some of this helps...
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