DIY sumb

Apr 10, 2012
Hello every one

I'm going to build my own sumb. I was thinking if doing it out of acrylic for 2 reasons. It would allow me to customize it as I wanted it As well it would give me practice for when I want to make my own larger acrylic tank.

I understand how a sumb works and how to build it. The area that I'm still the most confused about is the overhang box. wont be drilling my Aquarium. Its made of glass and has live fish in it already. With this being the case I will have to do something else. I would rather have my overflow box on the inside of my aquarium for the simple fact I want to minimize all my risk. Any ideas on how I could do this. Iv read that you can use a specimen box and hang it on the inside of the aquarium and then run your plumbing from that down to the sumb.

The other thing I'm still struggling to wrap my head around is how to get the water from the overflow box to the sumb without using a pump. Online they seem to use a T at the high point of the plumbing as it comes up from the over flow box heading to the sumb of the aquarium and they poor water in this T to start a siphon. Does this really work? What are the draw back to doing this?

I'v read that it helps to have two inflow pipes running from the aquarium to the sumb. How would you do this when you are using your own overflow box with out drilling the aquarium?

I would love to hear from people who were just as confused as I was and how they figured it out. Any helpful links or diagrams would be very helpful. Any last helpful tip or ticks to make and maintaining a overflow/sumb filtration system.

Thank you for your time I looks forward from hearing from you all.


Elite Fish
Jul 19, 2004
Cape Cod
Not positive about the overflow - when I had the same types of questions, everyone recommended drilling the tank (not set up yet in my case) rather than risking an overflow. Overflows can be prone to failure, but if you want to use one I have seen lots of recommendations for Lifereef overflows.

You don't need a pump to get the water down to the sump, gravity will do that (assuming the sump is lower than the display tank). You just need a pump to return water back up into the tank, and you'd want a siphon break on the return line so that if the pump were to fail (power outage or such), it wouldn't siphon water from the tank back down to the sump. Planning for a power outage or failure is a must - you need to have enough extra space in the sump so that the overflow can drain down into the sump without spilling over the sump.

When you first get everything set up, you want to figure out the maximum water level in the sump (the level over which the sump would spill over if power went out and the overflow box drained the tank down to the level of the overflow), and mark that level on the sump and never have more water than that in the sump.