GHL Dosers do far more than “just” dosing.
They can dose with extremely flexible schedules — up to 250 doses per day, from tiny corrections to large amounts for water changes or ATO.
But the true strength of a GHL Doser goes much further.

By integrating measurement data from GHL’s Director devices, the doser can automatically adjust upcoming dosages. Different control modes and precise adjustment settings give you the flexibility to achieve optimal stability in your aquarium.

What Control Options Does a GHL Doser Offer?

Level Control

With one or two level sensors (float or optical), a GHL Doser can automate:

• ATO (automatic top-off)

• automatic water changes

Level sensors can be connected:

• directly to a GHL Doser Stand Alone, or

• to a ProfiLux 4 when using a GHL Doser EXT.

KH Control

Requires a KH Director.
Two possible configurations:

• KH Director + Doser Stand Alone

• KH Director + ProfiLux 4 + Doser EXT

Both setups provide automated alkalinity measurement and KH-based dosage adjustments.

Control of Ca, Mg, K, and NO3

Requires the ION Director.
Same configuration options as with KH control:

• IOND + Doser Stand Alone

• IOND + ProfiLux 4 + Doser EXT

This setup enables automatic regulation of the most important ions in a reef aquarium.

What Control Options Does a GHL Doser Offer?

How Does It Work?

The KH Director or ION Director — or both — take a water sample.

• The KHD performs a titration.

• The IOND analyzes ions using ion-selective sensors.

The results are sent to the system’s “brain”:

• either a GHL Doser 2 / 3 (Maxi) Stand Alone, or

• a ProfiLux 4 (when using EXT dosers).

Based on these measurements, intelligent algorithms adjust upcoming dosages (increase or decrease) to reach the user-defined setpoints and maintain stable KH values or ion concentrations.

How Precise Is It?

Precision depends on how often you measure and environmental conditions.
Consumption of KH, Ca, and Mg, as well as NO3 levels, can fluctuate for many reasons — lighting, coral growth, feeding, filtration, and overall system dynamics.

The user decides:

• how often measurements run

• at what times

• and how aggressively adjustments should be made

Some aquariums require only occasional measurements, others benefit from several measurements per day for optimal stability.

With optimal settings and appropriate measurement intervals, KH fluctuations can be kept as low as ±0.1 dKH, and ion concentrations typically deviate by only a few percent.

Is It Safe?

Yes. Both the GHL Doser and ProfiLux Controller include extensive safety features:

• If a measurement appears suspicious, the system can trigger an automatic re-test.

• If an error is detected, automatic dosage adjustments are disabled.

• Adjustable limits define how much a dosage may be changed per cycle.

• Multiple internal safeguards protect against incorrect dosing or unexpected readings.

These mechanisms ensure stable and safe operation — even in demanding aquarium environments.

Where to buy? Visit the GHL Store