Reservoir Tubs for Custom Aquariums

The World's Only
Seamless Sump Reservoir Tub

Information and Specifications

Reservoir Tub

Seamless Sump® Reservoir Tub Key Features

  • One piece molded construction - no seams, no welds, no leaks!
  • Use as an evaporation tub, refugium tub, feeder fish tub, quarantine/medication tub, or simply to add water volume to the entire system
  • Use to compliment the sock tub or baffle tub, or as a stand alone sump or refugium system
  • Glass lid won't yellow or curl, great for UV plant lights
  • Easily fabricate holes for tubing, bulkheads etc. to the top or sides of the tub
  • Pre molded pilot hole dimples ensure consistent spacing and easy fabrication for a multitude of configurations
  • Recirculation tee in line with Reservoir pump allows controlled reservoir circulation without investing in another pump
  • Made from HDPE (read more on HDPE), a material far superior to acrylic or glass for this use
Mini Reservoir Tub

Seamless Sump® Mini Reservoir Tub Key Features

  • Same features and benefits of the standard reservoir tub
  • Slightly smaller footprint allows more tubs in smaller stands
  • HDPE construction has no welds, no seams, no leaks!
  • Great for evaporation or refugium use
  • Glass lid will not warp or turn yellow

Order Seamless Sumps & Supplies

Seamless Sump® Reservoir Tub

The patent pending Seamless Sump® Reservoir tub can be either a great compliment to the baffle tub to add water volume for evaporation or refusium use, or a stand alone sump for any hobbyist to create their own system.

Reservoir vs Refugium Configuration

The height at which a bulkhead hole is drilled and the tubs are connected will determine if the reservoir tub behaves as an evaporation tub or a refugium tub. Add a recirculation tee in line with one of your pumps and you can keep your reservoir water from being stagnant without the investment in another pump.

Evaporation Configuration


The water in the reservoir tub will equalize with the right half of the baffle tub / pump area and behave as an extension of the evaporation area of the baffle tank. This also adds water volume to dilute the harmful nitrates as well as prolongs the time you need to worry about the pumps running out of water due to evaporation. The more water volume you can add to your overall system the more significantly you increase the amount of time that can lapse between water changes. Additional water volume also makes it easier to control your salt to water ratios.

Reservoir Sump Low Configuration

Low Bulkhead Equilibrium Connection

High Evaporation Capacity


The water will not equalize past the height of the connecting bulkhead, therefore the reservoir tank will stay full even when the evaporation / pump chamber of the baffle tank water level gets low. In this configuration the reservoir tank will behave more like a refugium tank. This configuration has many possible uses such as growing live plants, live rock, feeder fish, even a quarantine / medication tank so long as you control cross contamination with the other tubs while the fish are being quarantined.

Reservoir Sump High Configuration

High Bulkhead Equilibrium Connection

High Refugium Capacity

Re-circulation Tees

Our re-circulation tees and return screens are a great way to add the small amount of circulation required to keep your reservoir tub from becoming stagnant.

Re-circulation tees come complete with a sturdy, adjustable, plated brass valve that will let you control the amount of water flow that is desired. Multiple outlet re-circulation tees are also available to create a multi-outlet manifolds to supply water to multiple tubs. Order re-circulation tees.

Recirculation Tee

Return Screens

Return screens should be either a single screen or a multiple screen manifold depending on your risk of clogging. Risk of clogging / flooding increases when you have debris, plants, fish, etc. inside your reservoir tank that can potentially block water flow from the return opening. Order Return Screens.

Return Screen

CAUTION has to be used with a recirculating solution as to not let the amount of water you introduce to the reservoir tub surpass the flow rate that is allowed to exit the tub. Our re-circulation tee solution allows you to control this process carefully without having to invest in another pump which often times will have too high of a flow rate for this use.You will also have to prevent the exit flow from clogging which would cause your reservoir tub to flood. We have many return flow screen solutions available to help achieve this goal. Any solution must be monitored closely for each application. Read our aquarium flooding warnings and instructions carefully for more details.

Stand Alone Sump - Great for the Do-it-yourself Hobbyist

Have a sump design idea of your own? The Seamless Sump® Reservoir Tub is a great starting point for the do-it-yourself hobbyist to create your own system. The pre-molded pilot hole dimples and flat surfaces on various heights and positions of the tub allow you to easily fabricate a wide variety of plumbing configurations. The HDPE one piece molded construction is a far better solution than glass or welded acrylic for this application. The recessed glass lid is a particularly great feature which will not warp or turn yellow with UV plant lights. The Seamless Sump®reservoir tub is a much better starting point than purchasing a glass or acrylic aquarium, or a tupperware container that wasn't really designed to be a sump.

Reservoir Tub

Key Specifications

Reservoir Specifications 1
Reservoir Specifications 2

Total Volume Capacity (full to glass lid): 22.6 Gallons
Ideal Functional Volume (half way up 1-1/2" side bulkhead): 16.4 Gallons