Maintaining alkalinity is paramount for stability and optimal coral growth in the intricate world of reef keeping. If you’re striving for exceptional coral conditions, alkalinity testing is non-negotiable. That’s where the KH Director® comes in – an essential component for water quality management in aquariums.

  1. GHL KH Director, white
  2. KH-Director_b_l_850x410

Available in Black or White

With the KH Director®, achieving and maintaining the perfect alkalinity levels has never been easier. Monitor, maintain, and control alkalinity effortlessly, ensuring your reef ecosystem thrives like never before.

Experience the difference with the KH Director®. Elevate your reef-keeping game today!

Achieve lush corals and healthy growth.
Sit back and enjoy your passion even more with the new KH Director®.
How does the KH Director® work?

The KH Director® is designed to operate alongside a GHL Doser 2 (2.1/2.2) Standalone or a ProfiLux® Aquarium Controller 3 or 4 with an additional Doser 2 (2.1/2.2) Slave (EXT) for seamless operation.

To integrate the KH Director®, it is connected to the Doser 2 (2.1/2.2) via its two inlets and one outlet, utilizing three dosing pumps for precise fluid transfer.

Here’s how the process works: a small aquarium water sample is initially directed to the KH Director®. Within the KH Director®, the KH value is accurately determined by gradually introducing a specialized liquid reagent while monitoring the pH value.

Once the measurement is complete, the sample water is then pumped out and collected in a separate container for safe disposal, ensuring the ongoing health and stability of the aquarium environment.

What are the costs for reagent and pH electrode?

At GHL, we prioritize providing cost-effective solutions for your aquarium needs, and we understand the ongoing expenses associated with automated KH monitoring and control. That’s why we’ve developed the KH Director with efficiency and affordability in mind.

With the KH Director, you can enjoy peace of mind knowing that your reagent costs are minimized. A single 1000ml bottle of reagent can last for up to 3 months, even with testing performed 4 times per day at a KH value of 8. Additionally, our specially designed pH electrode ensures accurate KH measurements and boasts an average lifespan of 1 to 2 years, further reducing long-term maintenance expenses.

Invest in the KH Director today and streamline your aquarium management while saving on operational costs.

Mastering KH Control

The KH Director® provides extensive adjustment options for KH control, catering to various systems like Balling® (Light), Triton®, or kalkwasser reactors.

Based on the difference between your target KH level and the current reading, it initiates precise adjustments for optimal aquarium conditions.

1. Add-on control mode

Use between 1 and 5 dosing pumps to add liquids to the aquarium depending on the control difference, KHD automatically calculates the appropriate quantities. The dosages can be time-delayed if the liquids are not to be dosed at the same time and divided into several sub-quantities per day. It is also possible that the dosing pumps used follow a dosing schedule, the quantities calculated by the KHD are then added to this dosing schedule.

2. Adaptive control mode

In this mode, 1 to 5 dosing pumps can also be used to add liquids to the aquarium depending on the control difference. In this mode, you set a dosing schedule for the dosing pumps involved, and the quantities of the dosing plan are varied by the KHD. If the KH value is correct, the dosing schedule remains unchanged, if the KH value is too low, all quantities of the dosing plan are increased as a percentage. If the KH value is too high, the quantities are reduced. The quantity change is dependent on the control difference and is calculated automatically.

3. Calcium reactor control mode

In this mode, a calcium reactor can be down-regulated depending on the KH value.
A calcium reactor is usually operated by CO2 addition and control of the pH value; the actual pH value in the calcium reactor is measured by a pH electrode. If you select this pH electrode in the KH Director Options, the KHD can switch off CO2 if necessary (KH target value reached), otherwise the normal CO2 control is activated. This mode is only possible with a ProfiLux aquarium computer.

KH Director® - Features

Seamless Connectivity

Stay effortlessly connected to your aquarium’s KH values anytime, anywhere with GHL Connect (App & Cloud). Monitor your water parameters with ease and gain peace of mind knowing you have access to crucial information at your fingertips.

Lab-grade Accuracy

Get precise KH measurements with just a 100 ml water sample – accuracy down to 0.1° dKH!

Customizable Testing

Customize your testing experience with the KH Director®! Tailor the test sample volume for each test to suit your needs, achieving an accuracy of approximately 0.2° dKH with smaller water samples.

Flexible Monitoring

Take control of your testing frequency! Adjust the number of measurements per day based on your KH value fluctuations, ensuring optimal monitoring tailored to your aquarium’s needs.

Reliable Safety Features

Trust in the KH Director®’s superior accuracy and safety features! Built-in valves ensure consistent measurement conditions and prevent sample liquid backflow into the aquarium, guaranteeing reliable and safe operation.

Efficient Reagent Usage

Save costs and maintain safety with minimal reagent fluid – only 1 – 3 ml per test!

Automated Data Logging

Harness the power of automated data logging with the KH Director®! Access past test results, identify sudden KH swings, and fine-tune your dosing regimen with ease.

Streamlined Liquid Supply

Simplify dosing with automatic supply of KH-boosting liquids for hassle-free maintenance enhancing convenience and efficiency in aquarium maintenance.
Depending on the method, one or more additional dosing pumps required.

Calcium Reactor Control

Alternatively, the KH value can also be influenced by controlling a calcium reactor.

LED Status Display

Stay informed at a glance with the KH Director®’s intuitive LED status display! The onboard GHL LED logo provides color-coded status indicators, allowing you to monitor your system’s condition with ease.

Seamless Integration w/ GHL System

Seamlessly integrate the KH Director® into your GHL aquarium system! Utilize the PAB (ProfiLux Aquatic Bus) connection for interference-free communication with other GHL PAB devices, ensuring safe operation and enhanced performance.

Low Maintenance Design

Simplify maintenance with the KH Director®’s user-friendly design! Access and maintain the pH electrode with ease, ensuring hassle-free calibration and replacement whenever needed.

Robust Design Built in Laboratory Quality

Every product we build is made to last the test of time. Trust in the durability and quality of the KH Director®! Crafted from robust materials and built to laboratory standards, the KH Director® ensures long-lasting performance and reliability.

Technical Specifications

Choose your preferred color option with the KH Director® available in black or white.

  • Dimensions (mm): 220 x 150 x 75 mm (w/out pH electrode)
  • Dimensions (in): 8.66″ x 5.9″ x 2.95″ (w/out pH electrode)

Scope of Delivery

KH Director® includes the following:

  • Device with integrated measuring cell
  • pH electrode, especially designed for the KHD, incl. calibration liquids
  • Testing reagent 500ml
  • Silicone tube 5m
  • Flex-PVC tube, 70cm
  • Waterfilter
  • Power-supply splitter-cable
GHL Connect App showing current Alkalinity data on Tablet and Cell-Phone
Unmatched Flexibility - Find your perfect Combination

The KH Director® can be operated in two ways:


The KH Director® is connected to the GHL Doser 2 (2.1, 2.2) Standalone via the ProfiLux Aquatic Bus (PAB).

GHL Doser 2.1+KH Director

With this option, the GHL Doser has full control over the measurement process and behavior of the KH Director. The GHL Doser will control both its dosing pumps and the valves in the KH Director. This will allow the doser to evaluate the measurement results and calculate the KH value.


The KH Director® is connected to the ProfiLux 3 (3.1, 4) and a GHL Doser 2 (2.1. 2.2) Slave or EXT via the ProfiLux Aquatic Bus (PAB).

ProfiLux+GHL 2.1 Slave Doser+KH Director

With this option, the ProfiLux has full control over the measuring process and behavior of both the GHL Doser and KH Director. The ProfiLux will control the dosing pumps in the doser and the valves in the KH Director. This will allow the controller to evaluate the measurement results and calculate the KH value.

Find the ideal combination to meet your aquarium’s requirements. Whether you’re drawn to the unparalleled versatility of the ProfiLux-Slave/EXT Doser/ KHD combination or the dynamic functionality of the GHL Doser 2.1/2.2 / KHD combination, our devices are engineered to integrate flawlessly.

If you opt for the Doser, we have something special just for you: Dive into our selection of irresistible sets explicitly designed for KHD and GHL Doser combinations, all at a lower price point than purchasing the devices individually.

Unmatched Flexibility - Find your perfect KHD-Set

Explore our enticing sets and discover the perfect KHD-Doser combination tailored specifically to your aquarium needs.

Please note that each KHD requires its dedicated controlling device and can only be controlled by one master device (ProfiLux or GHL Doser Standalone). Additionally, in a single system (comprising one master device and slave/extension devices), only one KHD can be utilized.

Operation of the KH Director always requires a GHL Doser with at least 3 pumps, depending on the configuration, either as an EXT (Slave) or as a Standalone version. Chose among these sets:

  • KH Director + GHL Doser 2.1/ 2.2 Standalone
  • KH Director + GHL Doser 2.1/ 2.2 Slave

Both sets have a significant price advantage compared to buying separately, they are offered in white or black and in these country versions: Schuko, UK, CH, USA/CND, AUS.
The sets include a PAB cable (50 cm / 19.6″).

Buy at GHL Store Europe

KH Director + GHL Doser Set black
KHD Set black

Buy at GHL Store US

KH Director + GHL Doser Set white
KHD Set white

KH Director® Connections:

KH Director Connections