H2Overflow® Stealthbox® Aquarium Overflow Box

The H2Overflow® Stealthbox® is the most versatile, silent, and reliable external aquarium overflow system available anywhere! This Stealthbox® works great with the Seamless Sump, or any other sump system to maintain fish tank overflow. The H2Overflow® Stealthbox® has 1200, 2400, or 3600 gallon per hour. capacity!

Custom Aquariums and Lifetime Aquariums now has an even more innovative solution for your fish aquarium overflow. The H2Overflow® Stealthbox® uses all the advantages of the H2Overflow® screen and combines it with the most versatile, practical, durable, and do-it-yourself-friendly external aquarium overflow box available today! The H2Overflow® screen provides an amazing volume of skimming with a minimal footprint, allowing up to 1200 gallons of water to flow safely and swiftly into the filter system. The large skimming area, with tapered screen openings and open top, minimizes the risk of a flood caused by debris, clogging the screen. Multiple H2Overflows® can be combined in one aquarium, greatly increasing the turnover rate for water through the aquarium overflow filter system. The skimming screen sits above the top rim of the aquarium, eliminating unsightly water lines, and the entire unit installs out of sight at normal viewing height. The H2Overflow® displays a fraction of the water that a traditional overflow box does, and still provides more inches of skimming.


Stealthbox® External Aquarium Overflow Overview

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Benefits of Using the Stealthbox®

The position of the H2Oveflow is adjustable so it is easy to configure your water circulation patterns and prevent shadowing caused by a fixed overflow sitting under the lights. The unit is easy to install into a single, 1-1/2" hole drilled at the top of the aquarium. No need for the leak risk of multiple holes drilled into the bottom of the tank.

The H2Overflow® is the perfect skimming screen for any sump filtration. Your aquarium can have:

  • Maximum surface area with a minimal foot print.
  • Up to 1200 GPH of flow through one H2Overflow®.
  • No visible water lines.
  • No flooding risk from holes drilled into the bottom of the tank.
  • The perfect screen for the Stealthbox® external overflow.

The Stealthbox® is the quietest and most dependable external aquarium overflow box you can buy anywhere! The top of the Stealthbox® sits evenly with the top of the aquarium, eliminating an annoying water line below the upper rim. The entire unit, including the box and the integrated fittings is constructed of the industry's strongest black PVC in a one-piece molded fabrication. There are no welds to crack or leak and the PVC material ensures a stronger glue bond with standard PVC fittings. Additionally, the Stealthbox® is designed with a wide array of integrated molded slip fittings and standard diameters, both inside and outside of the aquarium overflow box. Bulk head fittings are not necessary.

The Stealthbox® also has a PVC cover to prevent evaporation and further ensure quiet operation. Up to three H2Overflow® screens can be installed on a single Stealthbox®, allowing for one unit to handle up to 3600 gallons per hour of flow to the filter. In addition, the H2Overflow® Stealthbox® integrates perfectly with the Seamless Sump component filter system and any combination of Sock, Baffle, and Reservoir tubs.


Stealthbox® Key Features

  • Allows single, double, or triple H2Overflows® to seamlessly integrate with a multitude of output options for up to 3600 GPH! (Single — 1200 GPH, Double — 2400 GPH, Triple — 3600 GPH)
  • Many internal plumbing configuration options makes it the most SILENT and VERSATILE external overflow on the market!
  • Top of the Stealthbox® sits evenly with the top of the frame, not the bottom of the frame, meaning you can seamlessly control your water line to be below the lids, yet above the frame of your tank. NO MORE ANNOYING WATER LINE!
  • One piece molded solution. The box itself as well as the slip fittings on the bottom are made from one piece molded PVC. That means no welds that can be vulnerable to cracking and leaking.
  • Made from black PVC… not abs or polycarbonate, meaning it will create a stronger bond with off the shelf PVC fittings.
  • The Stealthbox® comes with 4 molded in 1–1/2” slip fittings, 3 @ 3/4” slip fittings, and 3 @ 1/2” slip fittings on the bottom inside and bottom outside of the box. Most versatile solution on the planet — let your imagination run wild with possibilities!
  • Comes standard with 2 @ 1–1/2” fittings in the center open and ready to use. Remaining fittings have pilot hole dimples ready to drill for whatever DIY configuration you decide.
  • Internal plumbing kits and ball valves available to aid in your various optimization goals.
  • Can be used as a complete gravity fed filtration solution — no external sump needed! As effective as a canister filter with far less risk of leaks and far easier maintenance!

Stealthbox® Internal Plumbing

Let your imagination run wild!

Our H2Overflow® Stealthbox® can be configured in a multitude of ways depending on your goals. Here are just a few of the ways to configure your Stealthbox®. With our ultimate kits, you can experiment between the several aquarium overflow configurations as your needs change. These are just a FEW suggested uses. Let us know what else you come up with, we would love to share even more ideas with our online community! Email photos and ideas to: reviews@customaquariums.com!


Single, Double & Triple H2Overflow® Configurations

Single H2Overflow 1200 GPH

Single H2Overflow® 1200 GPH

Double H2Overflow 2400 GPH

Double H2Overflow® 2400 GPH

Triple H2Overflow 3600 GPH

Triple H2Overflow® 3600 GPH


Configuration 1 - up to 3600 GPH

Our most popular configuration with a large system that has a protein skimmer involved. Position 10 you can manipulate with the ball valve to have just the right amount of water go into your skimmer, position 7 would take on 99% of the remaining water. You would open the vent to start the siphon, then close the vent to create a full siphon eliminating noise. Position 4 is to take on the remaining 1% of the water. This position 4 trickle is so small, the water sticks to the side of the pipe it makes virtually no noise. It also has a lot of excess capacity in case position 7 siphon gets interrupted. You would leave the vent off on position 4 to make sure a siphon is not necessary if position 7 gets clogged. Position 1 is a backup to the backup, a fail-safe to make sure absolutely no problem with any of the the other outputs results in an incident. This also works great with 4 sock tubs.

Stealthbox Configuration #1
Stealthbox® Configuration 1

Stealthbox Configuration #2
Stealthbox® Configuration 2

Configuration 2 – up to 1200 GPH

This is a popular configuration for a double sock tub with backup emergency redundancy. Position 7 is used to take on 99% of the water which can be accomplished by manipulating the ball valve. Position 4 is intended to take on the remaining 1% of the water and has enough excess capacity to take on more if position 7 loses its siphon. Position 1 is a backup to a backup for extra redundancy. This can be hooked up to a quad sock tub, or a double sock and teed to a baffle tub, or a reservoir tub that is in-line with a pump chamber so long as the reservoir is plumbed to the pump chamber with at least 1-1/2” tubing.


Configuration 3 – up to 1200 GPH

Same function as configuration 2, just done slightly differently making room for different uses of the remaining slip fittings. This is a popular fish tank overflow configuration for a double sock tub with backup emergency redundancy. Position 7 is used to take on 99% of the water which can be accomplished by manipulating the ball valve. Position 4 is intended to take on the remaining 1% of the water and has enough excess capacity to take on more if position 7 loses its siphon. Position 1 is a backup to a backup for extra redundancy. This can be hooked up to a quad sock tub, or a double sock and teed to a baffle tub, or a reservoir tub that is in-line with a pump chamber so long as the reservoir is plumbed to the pump chamber with at least 1-1/2” tubing.

Aquarium Overflow - Stealthbox Configuration #3
Stealthbox® Configuration 3

Aquarium Overflow Box - Stealthbox Configuration #4
Stealthbox® Configuration 4

Configuration 4 – up to 2400 GPH

This aquarium overflow configuration is a way to more evenly distribute water to 2 different socks where backup redundancy is not needed. Can be done with or without the elbows. If elbows used, we recommend not attaching the vent to at least one, and only have 1200 GPH per open vent. (If both vents open, 2400 GPH, one vent closed, 1200 GPH, never close both vents).


Configuration 5 – up to 2400 GPH

Same as configuration 4, but without the elbows. A very simple, elegant solution with more control than a single ball valve.

Aquarium Overflow Stealthbox Configuration #5
Stealthbox® Configuration 5

Aquarium Overflow Stealthbox Configuration #6
Stealthbox® Configuration 6

Configuration 6 – up to 3600 GPH

This is a very simple, safe solution for aquariums all the way up to 3600 GPH. By not using the 180-degree elbows, you eliminate all the risk involved with any kind of siphon. Just use the ball valves to manipulate water drainage until you hear no noise. Use up to 2 of the outputs merely as backups! A very popular fish tank overflow solution.

Again, these are just a few suggested uses. Let us know what else you come up with, we would love to share even more ideas with our online community! Email photos and ideas to reviews@customaquariums.com!


Stealthbox® Components

aquarium overflow box 1

aquarium overflow box 2

aquarium overflow box 3


With a total of ten molded fittings, the potential combination of filtration options is virtually limitless, making the Stealthbox® the most versatile overflow on the market, and the perfect rear-hanging, overflow box for the do-it-yourself filtration designer.

Custom Aquariums and Lifetime Aquariums provides beautifully designed and professionally engineered aquarium systems that are custom built to order for your house or office! Please contact Custom Aquariums to start building your customized aquarium today!


H2Overflow Stealthbox

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