Short answer by buyer
For two channels in a compact system, ReefDose 2 is the smallest ecosystem route. ReefDose 4 adds four heads and Red Sea’s coordinated dosing schedule. Kamoer X4 offers a wider feature set and level inputs at a similar price. GHL Doser 2.2 makes most sense when you already intend to build around ProfiLux.
| Pump / checked UK price | Channels | Published control detail | Ownership consideration | Best suited to |
|---|---|---|---|---|
| Red Sea ReefDose 2 £229 | 2 | ReefBeat app; single-drop accuracy; 0.2–1,000 ml daily per head | Compact route for a two-part or low-channel setup | Best when the ReefBeat ecosystem fits |
| Red Sea ReefDose 4 £329 | 4 | ReefBeat app; dynamic dosing queue; 0.2–1,000 ml daily per head | Four heads, 22.5 × 10.5 × 8.5 cm listed dimensions | Best all-round ecosystem option |
| Kamoer X4 £298–£299.50 | 4 | Wi-Fi; manual, auto and custom modes; 0.1 ml calibration claim; level inputs | More settings and sensors; check current UK support and app status | Best for feature-focused buyers |
| GHL Doser 2.2 SA £445–£465 | 2–4 | Stand-alone controller; ProfiLux/PAB expansion options | Higher entry price; strong fit for a GHL-led system | Best for an established GHL ecosystem |
What the channel count does not tell you
Four heads can still be awkward if the containers, tube holders and dosing points do not fit your cabinet. Check the pump’s minimum reliable volume, calibration process, tubing availability, power recovery behaviour and whether a missed dose is rescheduled or silently lost.
Calibrate the delivered volume
Use a graduated cylinder or syringe, run each head for a measured period and enter the actual output—not the factory assumption. Recheck after replacing tubing, moving the pump or changing the liquid. A small percentage error repeated every day becomes a large chemistry error over a month.
Sources and limitations
Red Sea’s ReefDose specifications list four heads, 0.2–1,000 ml daily dosing per head and ±0.05 ml accuracy claims. Current UK examples were checked at Complete Aquatics, Fit Filtration and Marine Aquatics. We have not independently measured accuracy, noise or app reliability.