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Mark Esquenazi's 240-Gallon Reef

Mark Esquenazi's 240-Gallon Reef

by Mark Esquenazi
Volume
240 gal
Dimensions
6ft x 2ft x 33"
Tank type
Mixed Reef (SPS Dominant Up Top)
Doses vinegar as a carbon source but mixes amino acids into it, so as phosphate drops he supplies coral-usable protein/nitrate to keep levels from crashing.

Mark Esquenazi's 12-year-old built-in 240-gallon peninsula reef is an old-school metal halide, SPS-dominant mixed tank with an open Tonga branch aquascape viewable from three sides. Flow comes from an external Reeflo Hammerhead and a hidden closed loop with bottom returns rather than visible powerheads. Husbandry centers on two-part dosing, a calcium reactor, vinegar-plus-amino carbon dosing, and rock-solid alkalinity stability around 9 dKH.

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Source: YouTube · REEF2REEF
What sets this tank apart
Vinegar + amino acid combo dose
Doses vinegar as a carbon source but mixes amino acids into it, so as phosphate drops he supplies coral-usable protein/nitrate to keep levels from crashing.
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Hidden closed-loop bottom returns
Uses a closed loop that draws water near the return and blows it out through four holes in the tank bottom, giving flow with zero visible powerheads on a three-sided peninsula.
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Wrasse-driven pest control
Stocks as many wrasses as will coexist so the tank never develops flatworm, red bug or other pest problems.
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See-through Tonga branch aquascape
Aquascaped with open Tonga branch rock by design so the three-sided peninsula stays viewable through the tank from every side.
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Equipment Breakdown

Shop this build · 1 of 5 items priced
Mark Esquenazi's 240-Gallon Reef — Full Equipment List
$400
est. build cost
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Lighting
20K 400W metal halides
Display lights ×3
Three 400W 20,000K bulbs, no LED or T5 anywhere — an unapologetically old-school lighting rig on a 12-year-old SPS-dominant reef.
Modern equivalent: EcoTech Radion XR30 G6 →
Flow & Circulation
Reeflo Hammerhead (~5,000 gph)
Reeflo
Hammerhead (~5,000 gph)
Return pump
🏋️ Workhorse
External ~5,000 gph beast that, together with the closed loop, delivers all the flow — not one powerhead visible in the three-sided peninsula.
Closed-loop manifold
Closed-loop flow
🔧 DIY mod
Draws water near the return and fires it back through four holes in the tank bottom — invisible flow for a peninsula viewed from three sides.
Monitoring & Control
Neptune Systems Apex
Neptune Systems
Apex
Controller
$399.95 Buy → ⚠ Out at Bulk Reef Supply Details →
Dosing
Two-part dosing
Ca/Alk supplementation
Two-part plus a calcium reactor cover Ca/alk, magnesium gets hit hard manually once a month — alkalinity stability around 9 dKH is the number that matters.

Husbandry & Notes

  • Dose two-part for calcium/alkalinity; hit magnesium hard manually once a month
  • Run a calcium reactor for phosphate reduction, pH lift and supplemental Ca/alk
  • Carbon dose vinegar to reduce nitrate/phosphate; switched from vodka for less cyano
  • Add amino acids mixed into the vinegar to feed corals and keep nitrate up
  • Empty and clean the skimmer cup every 3-4 days for efficiency
  • Keep many wrasses to control flatworms, red bugs and other pests
  • Match fish load and feeding to the system's filtration capacity
  • Prioritize alkalinity stability (~9 dKH); Ca and Mg fall into place after
Reported parameters
Alk (dKH)
9
What makes my tank a little bit different is it's old school in that it's still a metal halide tank.
The key to a skimmer, I believe, is changing the juice out every 3 or 4 days.
A fishless tank does not provide enough nutrients to the system.
I find alkalinity is the key to an aquarium. The key is stability.
We switched to vinegar and found that dosing vinegar was a better alternative than vodka. We got less cyano.