GHL KH Director Alkalinity Monitor

Product Showcase: GHL KH Director

Over the many years I have been keeping reef tanks I have learned that it is critically important to have stable, rock solid parameters, especially alkalinity. Like other reefers, I had no other choice but to use a hobby grade test kit to measure alkalinity. I tested weekly using a Salifert test kit and every now and then I would see a decent swing in results from one week to another.

Was it due to my calcium reactor not working properly, kalk in the kalk reactor expiring, a bad test kit or was there another reason? The bottom line during those instances was that something happened in between my weekly tests to cause alkalinity to swing. And sometimes those swings impacted the health of my SPS.

ghl kh director

Yes, I could have tested more frequently to flag any swings but that would have required more work and more money invested in test kits. Hobbyists for years have been asking for a more precise and automated means of measuring alkalinity and a number of manufacturers have recently released or will be releasing products to address this ask.

Which One to Choose?

I surveyed the different choices and landed on the GHL KH Director given my very positive experience with the GHL Doser 2.1 and the advantages the KHD has versus other competitive products, which are touched on by GHL in this video.


I also liked the fact that the KHD can be used to adjust dkh levels up or down. For example, if readings are drifting lower you can program the KHD to dose more alkalinity. You can also control dkh via a calcium reactor if you have a Profilux 3 or 4 controller by adjusting the pH set point.

GHL spent more then two years on research and development with the intent to manufacture a unit that is both reliable and precise (a pH probe is used to provide lab grade measurement values that GHL claims are within 0.1 dKH accuracy.

ghl kh director

Performance of GHL KH Director

I have been using my unit for a month now and thus far it has performed up to expectations. The consistency in results over this period has been very encouraging, with daily tests varying by a very small amount (+/- .4 dkh). Readings have even been close to my Salifert test kit results, although I have much more confidence in the KHD numbers given it’s lab grade quality and the human error possible with hobby grade test kits.

To obtain the most accurate results, it is important to follow GHL’s manual on how to setup the KHD, which is available on the Download section of their website, GHL also has a series of videos available on their YouTube channel to help with the setup.

3 Pumps Required

The KHD requires three GHL dosing pumps and is designed to work in conjunction with a GHL Doser 2.1 Stand-alone unit or a GHL Profilux 3 or 4 controller with a Doser 2.1 Slave. One pump is used to feed tank water into the KHD while a second pump feeds the KHD with reagent fluid. The third pump removes the test sample and used reagent fluid after a completed test, then dispenses it into a waste container.

ghl kh director

So that’s the skinny. One very important note to disclose, I now sell KH Directors but I only sell or recommend products I use personally and believe will be good for my readers. If you would like more information or would like to purchase a KHD please visit the Equipment section on

Additional Resources

If you would like some help with a new tank build, including help designing a custom aquarium, or help re-configuring your current setup then you can visit this page for more information. And if you are looking to add some equipment, I do sell GHL, Pax Bellum, Reef Octopus Calcium and Kalk Reactors and Royal Exclusiv products, including Dreamboxes, which is the equipment I use and recommend. I also sell Reef Brite metal halide and LED fixtures as well as Maxspect & IceCap Gyres.

As for additional insights and information, please explore my many other reef tank and SPS related articles as well as my YouTube channel. For an even deeper dive into reef tank care you can check out my Reef Keeping Master Class. This online course is an immersive and one of a kind educational tool designed to help reef aquarium hobbyists build and maintain a beautiful SPS reef tank. The course is a series of video presentations with some supplemental video from my YouTube channel. There are also quizzes to help students retain and understand the information presented in the course.

Need some frags…..I can help with that as well 🙂 Please visit my SPS Frag store to see what is available.

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