Possible sump build HELP! please


New member
Im wanting to build a simple cheap sump. Mainly for extra water volume and to remove some of my equipment from my DT. I do not want anything super fancy with multiple sections as far as I know. (or do I?) thats what im here for. I was thinking more along the lines of a rubber made tote that can hold a decent ammount of water and some live rock along with my HOB protein skimmer, heater, and HOB filter (that I run phosguard in). Just to clean things up and give me more volume. Would this be worth my time as far as keeping my tank happier? or would I be wasting time and money? Also if i were to do this, I would need an overflow box, since my tank is not drilled, and a pump. How do I know what pump to get for this? How many GPH is necessary?

Thanks for your time and opinions!


New member
Yes you will need an overflow box since your tank isn't RR. At a minimum you will need some baffles in the sump to creat a bubble trap. A small section for a refugium would help with keeping nutrient levels down as well. I would say it is worth your time and will chive the tank a cleaner appearance. Just do your research before starting on it.


New member
Additionally, skimmers like constant water levels if you don't have sections in the sump, then the entire sump level will fluctuate with your evaporation/top off.
I would consider at least one bubble trap or 2 sections.
Good luck with things!


New member
As far as the return pump you need to first figure out how many gpr your overflow will handle. Let's say you get a 600gph overflow. You would need a return pump that produces no more than 600gph in return pressure. I have a 1" overflow drain line that flows roughly at 600gph. My return pump is a Danner MagDrive 7 which is a 700gph pump. However, factoring in my vertical head loss as well as my Tee and 90 degrees, my return pump is actually only pushing around 400gph. If your return pump is pumping faster than your overflow can drain, you will end up overflowing your DT with all your sump water. Also the sump should be big enough to accommodate the amount of water that would back flow should the return pump ever fail. I've heard people say it should be at least 1/3 the size of your DT but personally my sump is 1/2 the size of my DT.


New member
Baffling your sump will allow you to trap micro bubbles before they have a chance to get to your return pump where they would then pour into your display tank which would be aesthetically unpleasing. Baffling will also give you chambers of water that stay at constant levels, with only the final chamber housing your return pump fluctuating in level as water evaporates over time. Housing your skimmer in a chamber with a constant water level would be a benefit, as otherwise you would have to frequently fine tune your skimmer to maintain the proper water level within it.

As for your return pump GPH, this is heavily dependent on what you're using your sump for. Assuming you already have suitable water movement in the DT via power heads and the like, and you are essentially only using your sump as housing for your skimmer, then the GPH need only be high enough to keep your skimmer running effectively. For example, if your skimmer is running at say 200gph, then running 1000gph by it via your return pump is overkill by about 800gph. In contrast, if your skimmer is running at 200gph yet your return is only moving at 100gph, then you've effectively cut the performance of your skimmer in half.

Remember that for whatever pump you buy, it will run a lower and lower GPH the higher you have to pipe the water to get it back into your DT due to pressure. This is known as head pressure, with the 'head' being the height at which you're pumping the water up to. So a pump that is rated 350gph may only be capable of 200gph at the top of your DT. Most pumps will provide the expected GPH at 4' head, the typical height of the average aquarium.

Your overflow box will need to be capable of handling a higher flow rate than what you will actually be providing, as a safety precaution. Matching a 800gph overflow with 800gph worth of actual flow is a recipe for disaster.