120 gallon SPS reef build with compatibility checks
A 120 gallon SPS build is a stability project first and a coral shopping list second.
Split heat around two 150 W heaters when possible.
Target the 40-60x band: 4,800-7,200 GPH before placement tuning.
Use bioload headroom rather than the most optimistic number printed on the product page.
A typical 120g footprint needs coverage across about 60 x 24 in and the 250-350 PAR band.
Monthly supplies often land around $145-$280 before livestock and repairs.
The final answer depends on actual equipment, source water, livestock, and maintenance plan.
What this build has to get right
- Plan high PAR with multiple fixtures for even coverage.
- Target 40-60x varied flow and avoid dead zones behind rockwork.
- Budget for testing, dosing, redundancy, and patient livestock pacing.
Better than a generic shopping list
A 120 gallon plan can fail even when every product is individually good. ReefCrafter checks whether heater wattage, flow, light spread, nutrient export, budget tier, and livestock intent all agree before the cart becomes the build.