Baffle-less sump design using spare tanks


Well-Known Member
BRS Member
I am designing my basement sump and am looking for feedback from more experienced hobbyists. This is the current design:

The entire sump will be inside the 120 gallon tank. The 2 herbie siphon drains and the larger emergency drain will come down from the floor above. They will drain into a 20 gallon tank sitting inside the 120g. The 20g will overflow into the 120g keeping a constant water height for a skimmer to be added. The return pump will sit inside a smaller (and notably shorter) tank on the right of yet to be determined size. The stable sump water height will be ~12" inches in the 120g giving me a sump volume of ~60g with 60g of spare room if the display tank back siphons (power outage + siphon break plugged for whatever reason). Finally, I will be able to drain ~25g from the system without having to turn off the pump for water changes which helps for a goal of mine to do weekly smaller changes easily.

Question: How would you add a refugium inside the 120g? Could it be as simple as letting the rest of the 120g be the refugium chamber only lighted in the center? If I did this, would it make sense to block the light from getting to either of the tanks on the sides?

Second question: Is it silly to do this to avoid making baffles and siliconing them in? Am I missing something in general?

Thank you!


Richard Kagen

Well-Known Member
BRS Member
Not sure I am an expert, but I have built 3 tank-based sumps and I am starting my fourth. I see a couple of potential issues:

1) the spill over from the 20 gallon will waterfall and likely create way more turbulence and bubbles than you might expect.
2) Running all of that flow through the refugium may cause a huge mess and from what i understand not all that good for macro algae growth
3) What are your plans for media reactors?

My first 2 sumps 55 gallon tanks, I cut my own acrylic dividers which were OK, my current one i had the local glass guys cut, polish and dime radius the bottom corners of 1/4 glass. less expensive than acrylic, stronger and the silicon bonds extremely well. I am putting the final touches on the design for my new 55 basement gallon sump which i am happy to share or show you.


Tim- 2019 BRS President
BRS Member
Fuge in the middle would make me think there would be hard to control where the algae goes. Higher chance of it clogging the return or getting somewhere it shouldn’t.

Egg crate barrier would work if you were using just chaeto I would think


Well-Known Member
BRS Member
@aresangel If I moved the 20g to the center, the fuge could then be on the far left, receive <50% of the flow and I could more easily control where light hits. I could use eggcrate or netting next to the 20g per your suggestion to reduce clogging risk. Sound reasonable?

@Richard Kagen
1) If I raised the stable water height to 1-2 inches lower than the 20g, do you think that would cut back on turbulence sufficiently?
2) how much flow would you aim for through the sump in general? If I use my existing return pump at 108" of head, I will only be getting ~500gph. Is that too low overall? Is that still too high for a fuge?
3) I dont really have any plans here, but one of the upsides to the 120g sump is space. How big are reactors generally? Could they go in next to a skimmer?

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