Home TECH SECTION Checker HANNA HI736 phosphorus Ultra Low Range – Review and video

Checker HANNA HI736 phosphorus Ultra Low Range – Review and video

Checker HANNA HI736 phosphorus Ultra Low Range - Review and video
Checker Hanna HI736 phosphorus ultra low range colorimeter.

In today’s article let’s talk again about measurements and tests. One of the fundamental parameters that we always should keep under control in our marine aquarium is, without a doubt, the quantity of phosphates in the water.

Amtra offerte per acquario

This article is also available in: italiano

This time we’ll try with a very precise and reliable tool, that is the Checker Hanna HI736 – Phosphorus ULR (Ultra Low Range).

The Checker HI736 is part of the famous line of equipment for the marine sector that Hanna Instruments, Italian company of international relevance, provided us some years ago. From the Hanna Marine Line series, recognizable from the brand in good sight on every “egg”, we have already reviewed the checker for nitrates at low range that corresponds to the acronym HI781.

We tried for you and after a long period of use we are now able to present you our review.

Phosphate and phosphorus

Now, for the ones that wonder why is so important to keep in control the presence of phosphates in a reef aquarium, we remind you that the phosphate (PO4) in the water can interact with the calcium carbonate (CaCO3), the principal material of the skeleton of hard corals. This interaction subtracts essential material for the coral and limits the building of the calcareous skeleton, slowing down its growth or even stopping it completely.

Il contenuto della confezione. In evidenza l'ovatto verde con le cuvette e i sei reagenti.
The inside of the box. In evidence the green egg with the cuvettes and the 6 reagents.

Moreover the presence of phosphorous can affect considerably the growth of unwanted algae. And we all know that, even if the algal phase is typical of the process of maturation, if it were to continue it would be attribuable to the presence of phosphate.

So, where were we?

We talked about phosphate measurement… so why would we need a device for phosphorous?

Because with it we would do even a more precise evaluation than with the Checker for phosphates.

Main characteristics of the Checker Hanna Hi736


The Checker HI736 works following the same principles of a photometer. A LED source at fixed wavelength (525 nm) is send through the liquid to measure and a silicon photocell does the detection of the light beam at the end of its run.

The resulting spectrum is analyzed and it will return the value of phosphorus in the sample.


The supply source is formed by a AAA battery of 1,5V, already given in dotation. It has to be placed in the inferior slot under a cap opened by a safety screw.

Range of functioning

The device can do lectures that go from 0 to 200 ppb (parts per billion). The nominal operating temperature goes from 0 to 50°C (32 – 122°F).


The resolution is 1 ppb.


The accuracy is +/- 5 ppb plus the +/- 5% of the measurement (considering lectures done at 25°C).

Il Checker Hanna HI736 nella sua classica forma a ovetto. Piccolo e discreto, sta nel palmo di una mano.
The Checker Hanna HI736 in its classic egg shape. Small and discreet.

The costs

The Checker HI736 Phosphorus ULR is sold in Hanna’s online shop at 55€ + IVA, to which you have to add the shipping cost.

In the package there are 6 bags of reagent for the measurement, the other tests have to be purchased separately. The package with 25 tests, that you’ll find with the code HI736-25, is sold at 10€ + IVA.

So, a single test, if you don’t consider the starting purchase, would be about 0,49 € for each measurement, which is more affordable. Plus, given the fact that the reagents are bagged singularly, the expiry date is pretty far. Their integrity can be preserved through a couple of years, if correctly kept, which is a great advantage if compared to the normal tests that usually don’t last over six or seven months after they’ve been opened.


The external wrap in cardboard, with the clear and linear Hanna’s graphic, contains the classic rigid back plastic package.

Il manuale del Checker HI736 presente nella confezione è in lingua inglese.
The manual of the Checker HI736 in the package is in English.

Inside the case you find, perfectly ordered, the contain:

  • the control device, with its egg shape, green colored;
  • an AAA battery of 1,5V;
  • nr. 2 calibrated cuvettes with a notch at 10ml and the closing cap;
  • nr. 6 phosphorus reagents in their bags;
  • the manual of instruction in English.

Our videoreview

Here below there’s our video of the presentation of the Checker HI736. You can add the subtitles in English and follow step by step the measurement.

The manual

The manual of instruction is in English. There’s also a short brochure with the graphic procedure that leads you step by step through the measurement. Both the files can be found in JPG format inside the download section of the HI736.

Well, in truth the test isn’t that complicate per sé. With few simple passages you can complete your measurement. Nonetheless, we quite liked the choice of putting a graphic procedure, that shows caring for the costumers and attention to the details. The passages are showed in with clarity and it’s difficult to make mistakes.

Add to this the possibility to download the safety data sheets of the reagents used in the procedures. In fact, Hanna has made available all the informations by law, guaranteeing clarity and transparency about the chemical products used and about the risks linked to their use.

On page two you can see the procedure with our suggestions to make it perfectly with no effort, plus our final opinion.

Aquarium Systems - Solutions proven by scientists for MORE THAN 50 YEARS
Previous articleLa luce è una delle chiavi del successo dell’acquario marino: approfondiamo
Next articleCome misurare il KH in modo automatico: Recensione Kh Keeper Plus
Laureata magistrale in Filosofia Teorica all'Università di Torino, ha completato il primo ciclo di studi a Macerata. Appassionata di scrittura e lingue straniere, su DaniReef collabora alla traduzione in inglese degli articoli. She earned a master's degree in Theoretical Philosophy at the University of Turin, but her studies started at the University of Macerata . She's passionate about writing and foreign languages, collaborates on DaniReef with the English translation of the articles.