This video showcases Ken Figueroa's 'Ancient Mariner' 100-gallon SPS-dominant reef tank, which was selected as Reef of the Month for May 2023. The tank is custom-built into a staircase landing with a unique slide-out feature for maintenance
This video showcases Ken Figueroa's 'Ancient Mariner' 100-gallon SPS-dominant reef tank, which was selected as Reef of the Month for May 2023. The tank is custom-built into a staircase landing with a unique slide-out feature for maintenance access. Ken details his equipment, husbandry practices, and philosophy, emphasizing high light, high flow, and a focus on proven, hardy corals.
The custom-built tank slides out 8 inches from its staircase landing integration, providing essential access for maintenance in a space-constrained setup.
Filtered Tap Water for ATO/WC
Instead of RO/DI, the reefer uses only pre-filter and carbon cartridges on tap water for top-off and water changes, simplifying water preparation.
Dual Alkalinity Supplementation
Both a calcium reactor and a 2-part dosing system are run concurrently to maintain stable alkalinity and provide redundancy against equipment malfunctions.
High-Wattage Metal Halide Lighting
The tank uses two 400w metal halide bulbs for intense SPS growth, a less common choice in modern reefing, with LEDs serving only for viewing.
Equipment Breakdown
Shop this build · 8 of 9 items priced
Ancient Mariner's 100-Gallon Acropora Reef — Full Equipment List
$3,003
est. build cost
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The tank is built into a staircase landing and slides out 8 inches for access.
Uses filtered tap water for ATO and water changes, bypassing RO/DI membranes.
Maintains high circulation flow with two MP40s and a Maxspect Gyre for SPS dominance.
Employs both a calcium reactor and a 2-part doser for alkalinity supplementation as a buffer against malfunctions.
Does not dose trace elements, nitrate, phosphate, nutrients, or coral food.
Relies on 400w metal halides for high light, with LEDs used only for viewing.
Performs daily fish feeding and calcium reactor checks.
Tests alkalinity weekly, cleans glass panels weekly, and performs biweekly 20% water changes.
Refills calcium reactor substrate and 2-part solutions every two months.
Cleans skimmer and circulation pumps every 3-4 months, and changes metal halide bulbs annually.
Started with a mix of old cultured artificial live rock, dry rock, and accumulated debris (muck) from a previous reef.
Maintains a bare bottom tank, having siphoned out aragonite that became covered with nuisance algae.
Focuses on hardy, proven 'old school' corals, particularly ORA corals.
Learned to wait 6-12 months before adding Acropora to a new reef to reduce losses.
Avoids keeping organisms known to be nearly impossible to keep alive in captivity.
Reported parameters
Salinity
1.026 sg
Alk (dKH)
8.5
Calcium
400
Nitrate
10 mg/l
Phosphate
<0.1ppm
Temp (°F)
78.5
pH
>7.7 <8.0
The tank slides out about 8 inches on a platform built on industrial slides. This allows for reef access.
I have a 50 gallon garbage can with a float valve that holds the filtered water for top off and water changes. There is a high volume bathroom ventilation fan with a high volume in-line supplemental fan that is constantly on.
I concentrate on trying to keep alkalinity at >8 dKh. The alk uptake is so high that if my Ca reactor or 2-part doser malfunctions alkalinity can drop to 4 or 5 dKh very rapidly!
HIGH light for SPS growth from top to bottom! 2 400 watt metal halides are NOT TOO MUCH for this goal.
Old school approaches are still valid and should be viewed as the baseline. Be wary of the newer theories, approaches, and recommendations.
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