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★ Featured in Atlantis
Neptune Systems Apex Controller
Neptune Systems

Apex Controller

Brain of the system
Monitoring · Controller

Continuous logging of temp, pH, ORP, water level, and leak detection.

Processor
32-bit ARM, color touch display (Apex Pro)
Probe inputs
4 (temp + pH + ORP + 1 expansion)
AC outlet ports
8 per EnergyBar 832 (sold separately)
Connectivity
WiFi + Ethernet
Power
24V DC, 60W brick
See it in the Atlantis tank build →
Apex Controller
$399.95 at Bulk Reef Supply
Buy →

Summary

Neptune Systems' Apex is the de facto reef controller in serious tanks. Monitors temp, pH, ORP, leak, water level, and switches every piece of equipment via AC outlet bars. The APEX programming language (Tasks/Profiles) is genuinely powerful — you can script 'if temp > 27.5, shut off return pump for 5 min' in ~5 lines. Steep learning curve, but the moment you have a real failure mode (heater stuck on, ATO overflowing), this pays for itself.

Best forany serious mixed reef build, 200-2000 L (53-528 US gal) Mountwall-mount or stand-side Skill advanced
Tank-size fit (log scale)
50L 100L 200L 400L 800L 1500L
Best-fit range: 200-2000 L
★ Atlantis verdict

"Has caught two would-be disasters at Atlantis since 2026-01: a heater stuck-on (cut power at 27.8°C), and an ATO float failure (cut PMUP based on PMUP+OPT water-level reading). Pays for itself the first time something goes wrong at 3 AM."

See it in the Atlantis tank build →

Controller layout

26.4°C PWR LNK NET COM 1 2 3 4 5 6 7 8 probes in 8x AC out eth Controller base 4 (temp + pH + ORP + 1 expansion) · 8 per EnergyBar 832 (sold separately) cloud-logged · alert-capable · script-driven
Probes feed in, AC outlets switch on/off based on script logic. Most reefers wire heater, return pump, ATO, and lighting through it.

Full specifications

Processor 32-bit ARM, color touch display (Apex Pro)
Probe inputs 4 (temp + pH + ORP + 1 expansion)
AC outlet ports 8 per EnergyBar 832 (sold separately)
Connectivity WiFi + Ethernet
Power 24V DC, 60W brick
App Apex Fusion (iOS / Android / web — FREE cloud)
Programming APEX DSL — Tasks / Profiles / Virtual Outlets
Modular AquaBus expands to PM1, PM2, PM3, FMM, Trident, DOS, COR
Dimensions 200 × 110 × 35 mm (base)
Warranty 1 year (Neptune US)

What sells it / What holds it back

✓ Pros
✓ De facto standard — huge community, every reef DIY guide assumes Apex
✓ Modular: start basic, add probes/dosers/Trident/COR-20 as the build grows
✓ Apex Fusion cloud is FREE — no monthly subscription
✓ APEX scripting handles complex logic that simple controllers can't (e.g. dose-on-condition, ramp-on-photoperiod)
✓ Real failure-mode coverage: stuck heater, ATO overflow, leak, temperature spike
✗ Cons
✗ Steep learning curve — APEX scripting is its own DSL, takes a weekend to internalize
✗ EnergyBar (the AC switching) is sold separately — adds ~$300 to start
✗ Per-outlet 1500W max — high-wattage heaters need a dedicated bar
✗ iOS app feels dated; web Fusion is the better experience
✗ pH probe ages — calibrate every 60 days, replace every 12-18 months

What's in the box

  • Apex base controller
  • 24V DC power adapter
  • AquaBus cable (connects to EnergyBar)
  • Temperature probe (1m cable)
  • Lab-grade pH probe (BNC)
  • Quick-start booklet

Setup & dial-in

1
Step 1: Plug in base, open Apex Fusion app, connect to home WiFi (Apex creates its own SSID for first-pair).
2
Step 2: Connect EnergyBar via AquaBus, label each outlet in Fusion (Return Pump, Heater 1, Skimmer, etc).
3
Step 3: Calibrate pH probe in 7.0 + 10.0 reference fluids — your readings will drift if you skip this.
4
Step 4: Place temp probe in SUMP, not display — stray current from heaters can throw display-tank readings.
5
Step 5: Write your first Profile: Heater control with hysteresis. Don't over-engineer — start with `If Temp < 26.4 Then On; If Temp > 26.8 Then Off`.
6
GOTCHA: Test your alert thresholds with the Fusion app's notification preview before trusting them at 3 AM.

Maintenance schedule

every 60 days
Recalibrate pH probe
12-18 months
Replace pH probe
monthly
Backup APEX config (Fusion)
quarterly
APEX firmware update
every 3 months
Clean outlet bar dust
annually
Inspect AquaBus cables

Pairs with / Replaces

Pairs with
Tunze Osmolator Nano 3
Tunze
Osmolator Nano 3
EHEIM 50W Heater
EHEIM
50W Heater
Tunze DOC Skimmer 9410 DC
Tunze
DOC Skimmer 9410 DC
Neptune Apex Temperature Probe
Neptune Apex
Temperature Probe

Featured in famous tanks

This piece of gear is in the documented build of 14 tank tours.

Project Atlantis ★ 60 gal
Project Atlantis
Atlantis Reef Keeping
LPS dominated
Sanjay Joshi's 700-Gallon SPS Reef ★ 700 gal
Sanjay Joshi's 700-Gallon SPS Reef
Dr. Sanjay Joshi
SPS-dominant
BRS 160 — The "Real Reef" Mixed Build ★ 160 gal
BRS 160 — The "Real Reef" Mixed Build
Ryan Batcheller (BRS)
Mixed reef
Mr. Saltwater Tank — 450-Gallon Mixed Reef ★ 450 gal
Mr. Saltwater Tank — 450-Gallon Mixed Reef
Mark Callahan
Mixed reef
Graham Stephan's 310-Gallon Reef 310 gal
Graham Stephan's 310-Gallon Reef
Graham Stephan
Mixed Reef
Blaine's 100-Gallon Soft Coral Reef 91 gal
Blaine's 100-Gallon Soft Coral Reef
Blaine
Mixed Reef, Soft Coral Dominant
Matt Schmidt's 80-Gallon Reef 80 gal
Matt Schmidt's 80-Gallon Reef
Matt Schmidt
Mixed Reef
The NYC 75-Gallon Reef 75 gal
The NYC 75-Gallon Reef
Mixed Reef
The Bulletproof 150-Gallon Reef 150 gal
The Bulletproof 150-Gallon Reef
Mixed Reef
Mark Esquenazi's 240-Gallon Reef 240 gal
Mark Esquenazi's 240-Gallon Reef
Mark Esquenazi
Mixed Reef (SPS Dominant Up Top)
Tidal Gardens 700-Gallon Coral Farm 700 gal
Tidal Gardens 700-Gallon Coral Farm
Than Thein
Coral propagation / display
Jake Adams's Reef Builders Lab Tank 300 gal
Jake Adams's Reef Builders Lab Tank
Jake Adams
Mixed reef R&D
Dwayne's 4ft Waterbox Reef
Dwayne's 4ft Waterbox Reef
Dwayne
Reef
Andrew's 1,000-Gallon Mixed Reef 1,000 gal
Andrew's 1,000-Gallon Mixed Reef
Andrew
Mixed Reef

Where to buy

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Retailer Price Stock Checked
Bulk Reef SupplyAff bulkreefsupply.com
$399.95 Out today Buy →

Side-by-side compare

This product
Neptune Systems
Apex Controller
$399.95
Neptune Systems
Trident Automated Tester
from $699.99
Processor 32-bit ARM, color touch display (Apex Pro) —
Probe inputs 4 (temp + pH + ORP + 1 expansion) —
AC outlet ports 8 per EnergyBar 832 (sold separately) —
Connectivity WiFi + Ethernet —
Power 24V DC, 60W brick 8 W
App Apex Fusion (iOS / Android / web — FREE cloud) —

More monitoring to consider

Neptune Systems Trident Automated Tester
Neptune Systems
Trident Automated Tester
from $699.99

External resources

📄 Manual / PDF 🌐 Manufacturer page ▶ YouTube review