Home Automated Water Change System Build
Automated water changes are the upgrade most reefers regret not doing sooner. Replace 4 hours a week of bucket-hauling with 5 minutes of mixing salt in a dedicated barrel.
Two-bucket gravity setup (cheapest, $80)
Simplest AWC: dedicated mixing barrel + dedicated drain barrel. Manual fill timer pulls X gallons out per day, replaces with X gallons fresh. Use Apex/Inkbird-controlled solenoid valves to automate the swap.
Apex AWC system ($300-500)
Neptune Apex DOS dosing pump (or 2x dosers): one pulls old water to drain, one pumps fresh saltwater into sump. Schedule for daily 2-5% changes (slow, gentle, parameter-stable).
Setup: salt mix barrel at room temp, heater + pump for mix-circulation, RO/DI top-off, brute trash can or 32-gal stock tank.
Sicce Voyager + timer ($150)
Mid-tier: Sicce Voyager pump on a digital timer pulls water from sump, dumps to drain. Second pump on 2nd timer fills from salt-barrel. Less precise than Apex but 3x cheaper.
Critical failsafes
- Float switches on sump + salt barrel - kill power if water level wrong
- Leak detection mat under sump cabinet ($40 Apex LDM)
- Hard-coded daily max change - never more than 5% per day in case sensor fails
- Drain to sink, not floor - even small leaks find a sump pit
Salt mix barrel sizing
Mix enough for 2 weeks of changes minimum. 75g system at 5% daily = 4 gal/day x 14 = 56 gal needed. Use a 65g brute trash can. Mix 30 min, heat to 78°F, circulate 24h before first use.
Daily AWC volume calculator
For SPS reefs: 1-3% per day. For mixed reef: 1-2% per day. For FOWLR: 5% weekly is usually enough. Use our water-change calculator to dial in.
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