Large Hidden Water Reserve
The 220-gallon basin supports the recirculating-water needs of large or multi-fountain displays without requiring an open pond.
Fountain Reservoir Basin – 52" Altum AquaBox®
$1,299.99
• Basin measures 52.5" x 52.5" x 20"h
• 2 plastic grates measure approx. 24" x 48" each
• 220 gallon capacity
• Max static load: 2,500 lbs
• Weighs approx. 110 lbs
• Includes 1 center support column, pump access cover, and mesh sediment screen
• Lifetime Warranty
52-inch square subsurface fountain reservoir
Altum AquaBox®: A Strong Foundation for Large Fountain Displays
The Blue Thumb Altum AquaBox® is a high-capacity polyethylene basin that supports large or multiple recirculating fountains while concealing the pump, plumbing and water reserve below the finished surface. Its removable two-piece grate and dedicated pump-access cover keep service points reachable after installation.
52.5 in. squareOverall footprint
220 gal.Reservoir capacity
Up to 2,500 lb.Maximum static load
Approx. 110 lb.Basin assembly weight
Made in USAPolyethylene construction
Built for Substantial Water Features
Strength with Service Access
Four molded supports, an included PVC center support and a two-piece grate form the working foundation, while the 7 × 9.5-inch pump opening remains accessible.
Flexible Project Planning
Built-in grate openings simplify plumbing routes, and the basin can accept an optional auto-fill valve, extra supports, a splash apron or an aluminum grate upgrade.
Is the Altum the Right Basin for Your Site?
Choose the Altum when a large or multiple-fountain layout needs a square 52.5-inch footprint, generous water reserve and high static-load capacity. Allow additional room around the basin for excavation, leveling, backfill, utilities and the finished landscape.
Check Weight Distribution
The published rating is up to 2,500 pounds of static load. Concentrated point loads and fountain placement still matter. Use the included center support as directed, and evaluate additional 17-inch Altum support columns or the Altum aluminum grate upgrade for demanding layouts.
Need a Smaller Reservoir?
If your project does not require a 220-gallon square basin, compare the round 48-inch Achelous AquaBox® or browse all Blue Thumb fountain basins.
What Comes with the AB52AB
Reservoir & Support
- Square polyethylene reservoir basin
- Four molded internal support columns
- One 4-inch rigid PVC center support
Top & Service Access
- Two-piece plastic grate top
- 7 × 9.5-inch pump-access opening and cover
- Mesh sediment screen to help reduce debris entry
Altum AquaBox® Specifications
Item / SKUAB52AB
Overall dimensions52.5 × 52.5 × 20 in. H
Inner reservoirApprox. 48 × 48 × 16.5 in. H
Full grate / inner seat48 × 48 × 2.8 in. H
Grate configuration2 halves; approx. 24 × 48 in. each
Pump access7 × 9.5 in.
Reservoir capacity220 gal.
Maximum static loadUp to 2,500 lb.
Product weightApprox. 110 lb.
Basin materialPolyethylene (PE)
Intended useLarge or multiple fountains
ManufacturingMade in the USA
Optional Accessories & Finishing Materials
These items are sold separately. Select only what fits your fountain, water supply, weight distribution and site plan.
Automatic Water-Level Control
Add the ABDAUTO Fountain Basin Auto Fill Kit. Pair it with the 30 PSI Regulator when supply pressure exceeds 30 PSI.
Splash Management
The 76-inch-square Splash Apron for Reservoir/Basin extends beyond the basin to help capture water that lands outside the grate.
Decorative Pebble Finish
The current Altum specification sheet recommends 8–10 bags to cover the grate. Choose 40-pound bags of black polished pebbles or mixed polished pebbles. Actual coverage varies with stone depth and fountain footprint.
Support for Demanding Layouts
Use project-specific load planning to determine whether additional support columns or the aluminum grate upgrade is appropriate for concentrated heavy loads.
Plan the Installation Before Digging
Review the official installation guide before excavation. Locate underground utilities and confirm access to clean water and a suitable GFCI-protected electrical outlet for the pump selected for the finished system.
Lay Out the Site
Trace approximately 1–2 inches beyond the 52.5-inch-square basin footprint and orient the future pump-access opening toward electrical service.
Excavate
For an in-ground Altum installation, the manual calls for digging approximately 21 inches deep, slightly wider than the basin, and removing sharp rocks and roots.
Level the Base
Level with sand or small gravel and tamp thoroughly. The basin must sit on the prepared base rather than hang from its upper lip.
Set & Backfill
Set the basin level at approximately 1 inch below grade, then compact backfill as work progresses. With the optional splash apron, the guide calls for about 1.5 inches below grade and grading toward the basin.
Install Equipment
Position the selected pump, tubing and optional auto-fill equipment, then install the PVC center support and align both grate halves according to the manual.
Fill, Test & Finish
Fill with clean water, test flow and service access, and correct any splash or leveling issues before placing decorative pebbles and completing the landscape.
Routine Care & Seasonal Planning
During the Operating Season
- Maintain enough water to keep the selected pump submerged while operating.
- Check more often during hot, dry or windy weather and with wide splash patterns.
- Remove leaves and debris before they restrict water return or the pump intake.
- Keep the pump-access cover reachable after adding decorative stone.
- Clean the sediment screen and service the pump as their condition and instructions require.
Before Freezing Weather
Winter care depends on the fountain piece, pump, plumbing, auto-fill line, local climate and whether the basin is installed above or below grade. Do not automatically drain a buried reservoir. Follow the instructions for the complete fountain system and protect equipment that can hold vulnerable water.
Review Blue Thumb’s winter-care guideProduct Resources
Use the current documents for final measurements, grate preparation, site work, equipment placement, optional auto-fill setup and warranty terms.
Optional Auto-Fill Installation Video
This official Blue Thumb walkthrough covers the separately purchased ABDAUTO Fountain Basin Auto Fill Kit. The auto-fill kit, regulator and water-supply connection are not included with the AB52AB basin.
Video: “Fountain Basin Auto Fill Kit - 1/2" Step by Step Installation (ABDAUTO)” — courtesy of Blue Thumb.
Questions About Fountain Fit or Load Placement?
Blue Thumb’s Sales and Technical Team can help review fountain dimensions, weight distribution, pump selection, splash pattern and site requirements before you order.
Frequently Asked Questions
Key details to confirm before choosing equipment and preparing the site.
Is the Altum AquaBox a complete fountain kit?
No. The AB52AB is the basin assembly. The fountain, pump, tubing or plumbing, decorative pebbles, auto-fill equipment, water connection, electrical service, site materials and labor are sold or provided separately.
What is included with the AB52AB basin?
It includes the square polyethylene basin with four molded supports, two-piece plastic grate, one 4-inch rigid PVC center support, pump-access cover and mesh sediment screen.
How much space should I plan for?
The basin measures 52.5 × 52.5 × 20 inches high. For an in-ground installation, the manual calls for an excavation approximately 21 inches deep and about 1–2 inches wider than the basin, plus adequate working room for leveling, backfill, utilities and the finished landscape.
Will this basin support my fountain?
The published maximum static-load rating is up to 2,500 pounds, but fountain footprint, point-load concentration and placement over the support structure also matter. Review the exact layout before ordering; additional 17-inch supports or the aluminum grate upgrade may be appropriate for demanding installations.
Does the basin include a pump?
No. Select the pump and plumbing for the fountain’s required flow rate, lift and desired water pattern. The pump sits inside the reservoir beneath the access cover.
Is the sediment screen included?
Yes. Blue Thumb states that new Altum and Achelous AquaBox basins include a mesh sediment screen as standard equipment. The separately listed screen is intended for replacement or for compatible older basins that do not already have one.
How many bags of polished pebbles are recommended?
The current Altum specification sheet recommends 8–10 bags for finishing the grate. Blue Thumb’s black and mixed polished pebbles are sold in 40-pound bags. Actual coverage varies with stone depth, fountain footprint and the amount of grate left exposed.
Can the Altum basin be installed above ground?
The official specification sheet says AquaBox basins may be installed in-ground or above-ground depending on the desired display elevation. The supplied installation guide details an in-ground installation, so review structural support, access and exterior finishing with Blue Thumb for an above-ground project.
How should the basin be winterized?
Winter care depends on the complete fountain, pump, plumbing, auto-fill components, installation style and climate. Protect equipment that can hold freezing water and follow the exact fountain and pump instructions. Do not automatically empty a buried reservoir; Blue Thumb notes that many buried systems remain partially or fully filled to help resist freeze/thaw ground movement.
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