Hidden reservoir system for your drilled stone
The 36-inch Bubbling Boulder Conversion Kit supplies the below-grade reservoir, support deck, 800 GPH pump and matched plumbing needed to turn a customer-supplied drilled rock or natural-stone feature into a self-contained fountain. Water rises through the stone, returns across the concealed grate and recirculates from the 60-gallon basin below.
Choose this kit for: a customer-supplied drilled boulder, basalt column, drilled rock or compatible real-stone feature up to 24 inches high. The stone itself is not included. Using a pot, urn or vase instead? Choose the 36" Achelous AquaBox® Fountain Conversion Kit (#AB36KIT).
Choose by fountain type
Both kits use the same 36-inch Achelous AquaBox® basin and the same included 800 GPH pump. The deciding difference is the plumbing configuration and the type of fountain feature placed on the grate.
Buy this kit when: water will travel through a drilled passage in a boulder, basalt column, drilled rock or compatible natural-stone feature.
Buy the standard fountain kit when: the fountain is a compatible hollow vessel that uses an internal standpipe and bulkhead connection.
Why this system works
The reservoir installs below the finished grade, leaving the stone and moving water as the focal point instead of an exposed pond.
An adjustable 800 GPH Mag-Drive pump, tubing and flow control are supplied together for a medium-size real-stone fountain.
A two-piece grate, pump-access area and sediment screen help support the feature while keeping routine pump access practical.
Plan around the basin's 39.5-inch outside diameter, not only the 36-inch grate measurement. Blue Thumb lists this kit for a drilled rock up to 24 inches high and a maximum static load of 1,000 pounds. The rock's base must distribute its weight securely over the grate and support system, and its water pattern must return to the reservoir rather than splash beyond it.
For a taller or larger feature, compare the 48-inch Bubbling Boulder Conversion Kit, which increases reservoir capacity, support rating, pump flow and maximum listed rock height.
System contents
The kit includes the hidden recirculating system. You supply the visible drilled stone, finish material and prepared installation site.
The linked pump page offers three sizes. The included variation is the 800 GPH model, item #PB2583.
The drilled boulder or stone fountain, decorative pebbles, lighting, excavation tools, compacted base material, backfill, water-supply work, electrical service and surrounding landscaping are not included. The optional auto-fill kit and splash apron are sold separately.
Add the Fountain Basin Auto Fill Kit (#ABDAUTO) when a connected water supply and automatic replenishment are desired. Blue Thumb recommends pairing it with a 30 psi regulator.
The optional Splash Apron (#ABBSA36) helps return overspray to the basin. Its installation changes the recommended basin depth and surrounding grade.
Blue Thumb recommends 4–5 bags of polished pebbles to finish the grate. Choose black polished pebbles or mixed polished pebbles; both are sold separately.
Verified technical details
*Pump wattage can vary with head pressure.
| Model | Overall Basin | Capacity | Static Load | Pump | Max. Rock Height |
|---|---|---|---|---|---|
| 36" Kit (#AB36BB) | 39.5 in. dia. × 16 in. H | 60 gal. | 1,000 lb. | 800 GPH | 24 in. |
| 48" Kit (#AB48BB) | 51.5 in. dia. × 16 in. H | 95 gal. | 1,500 lb. | 1,110 GPH | 36 in. |
Plan before digging
This is an in-ground fountain installation that requires excavation, careful leveling, weight support, plumbing and GFCI-protected electrical access. Use this overview for planning, then follow the official basin and pump manuals.
Select a viewing location with practical access to clean fill water and a dry, flood-protected GFCI outlet. Locate underground utilities before excavating.
Mark roughly 1–2 inches beyond the basin top and excavate 17 inches straight down. Remove sharp rocks and roots, then level and compact a sand or small-gravel base.
Position the basin level with its top approximately 1 inch below grade. Orient pump access toward the electrical service, then backfill and compact evenly. A splash apron changes the recommended depth to about 1.5 inches below grade.
Plan the stone and tubing position before drilling. The basin guide calls for a 1.5-inch hole saw when grate holes are needed and identifies areas that must not be drilled over molded supports.
Install the PVC center support, pump and tubing beneath the access area. Feed the tubing through the compatible drilled stone and connect the included flow control. Confirm stable weight distribution before operation.
Clean the basin, fill it with clean water and start the submerged pump from the GFCI outlet. Adjust the flow, confirm that splash returns to the reservoir, then add suitable finish stone without blocking pump access.
Long-term ownership
Evaporation is often around 1–2 inches per week, but wind, humidity, rainfall and splash can change refill frequency. Keep the pump fully submerged and never allow it to run dry.
Keep the sediment screen and reservoir clear. If performance drops, unplug the pump before cleaning its inlet strainer, foam pre-filter and impeller area according to the pump manual.
Before freezing conditions, unplug and remove the pump, empty it and store it where it cannot freeze. Protect exposed plumbing from trapped water and follow the manuals for complete seasonal care.
Operate the pump submerged and connect its 3-prong plug only to a dry, flood-protected GFCI outlet. Unplug it before handling or servicing. Never lift the pump by its cord; if the cord is damaged, Blue Thumb states that it cannot be replaced and the pump should be discarded.
Achelous AquaBox® basin: Lifetime limited warranty on Blue Thumb engineered-plastic components for the original purchaser, subject to proper installation and the complete warranty terms.
PB2583 Mag-Drive pump: Five-year limited warranty from the original purchase date. The impeller is excluded.
Warranty coverage does not include associated labor or freight costs. Review the linked Blue Thumb warranty document for complete conditions and exclusions.
Official Blue Thumb documents
Review the basin installation guide and pump manual before site work begins. Keep the documents available for assembly, troubleshooting and seasonal service.
Understand the included pump
This official Blue Thumb guide explains the Mag-Drive pump family and routine impeller maintenance. The exact pump included with this kit is the 800 GPH PB2583.
Blue Thumb's Sales and Technical Team can help you review the boulder's footprint, weight distribution, drilled water path, expected splash pattern and installation plan before ordering.
Choose this AB36BB Bubbling Boulder Conversion Kit for a drilled boulder, basalt column, drilled rock or compatible real-stone feature. Choose the AB36KIT 36" Achelous AquaBox® Fountain Conversion Kit for a compatible pot, urn or vase that uses an internal standpipe. Both kits use the same 36-inch Achelous basin and 800 GPH pump; the plumbing configuration is different, so choose according to the fountain feature—not the basin size.
No. This is the hidden reservoir, support, pump and plumbing system used beneath a customer-supplied drilled boulder or compatible real-stone feature. Decorative pebbles, lighting and landscaping are also sold separately.
Blue Thumb lists the 36-inch kit for a rock up to 24 inches high and a maximum static load of 1,000 pounds. Height and weight are not the only considerations: the base footprint, weight distribution, drilled water path, desired flow and splash pattern must also suit the basin.
The grate and basin inner seat measure 36 inches in diameter. The outer lip increases the complete basin footprint to 39.5 inches, which is the dimension to use for site planning.
The kit includes the Blue Thumb PB2583 Medium Mag-Drive pump. It is rated for up to 800 GPH, with adjustable flow, 9.3 feet of maximum head, a 20-foot cord, 3/4-inch outlet and submerged-only operation.
No permanent connection is required for manual filling, but the operating water level must be checked and maintained. The optional #ABDAUTO auto-fill kit can be connected to a suitable water supply for automatic replenishment.
No. Blue Thumb recommends 4–5 bags of polished pebbles to cover the grate, available separately in black or mixed color. Other suitably sized decorative stone may be used if it will not fall through the grate or block pump access.
The Achelous guide calls for an excavation about 17 inches deep and approximately 1–2 inches wider than the basin top. The base must be level and compacted, and the basin top is normally set about 1 inch below grade. Follow the manual because a splash apron changes the recommended depth.
Before freezing conditions, unplug and remove the pump, empty it and store it in a location where it cannot freeze. Protect exposed plumbing from freeze damage and use the linked basin and pump manuals for complete seasonal-care instructions.
Compare the 48-inch model when the 36-inch system's 39.5-inch footprint, 60-gallon capacity, 1,000-pound static-load rating, 800 GPH pump or 24-inch maximum listed rock height is not sufficient. The 48-inch kit increases each of those system limits, but the exact stone and splash pattern still need to be evaluated.
