A critical ‘building block’ for life, Phosphorus exists in seawater in a variety of organic and inorganic forms. In elevated levels these Phosphates have the potential to fuel nuisance algae blooms and can even interrupt the growth of calcifying organisms. Typically Phosphates are introduced to aquaria through the foods we add, but they may also creep in through household water supplies (particularly if tapwater is used), from certain salt mixes and from certain low grade activated carbon brands.
Luckily, there are ways to limit and even export Phosphates from our tanks. The most common methods include the use of RO/DI water, low Phosphate fish foods, algae harvests (ideally from a sump-based algae filter for example), effective protein skimming, addition of Limewater and the use of binding agents such as Granular Ferric Oxide (GFO).
Given that elevated levels (generally anything above 0.05ppm, or 0.03ppm in SPS systems) have the potential to negatively impact the ‘desirable’ organisms kept by reef-keepers it is no surprise that many of us attempt to go beyond simply waiting for an algae bloom to happen before taking action, and seek to determine trends in the levels present in our systems. Unfortunately, testing Phosphorous is not as simple as it sounds though. As well as a confusing array of different test-kits, many simply don’t offer the accuracy necessary to be of much use, and furthermore rely on colour comparisons to obtain a final result which can be subjective and prone to misinterpretation.
Although around double the price of a reasonable quality colour comparison type test, the Hanna Phosphorous ULR checker offers superb ease of use and an ultra-low range measurement (1 part per billion resolution) of Phosphorous. This isn’t just a test of the inorganic orthophosphates like other test kits either… instead a wider spread of Phosphate forms are measured and this provides a more detailed and accurate picture. Really, this device is so simple to use… just fill one of the glass cuvettes with a sample of the test seawater and press the button to zero the unit. Next, remove the cuvette and add a sachet of the reagent, shake for 2 minutes and then re-insert into the checker, then press the button again. After a 3 minute countdown, the result is displayed on the screen as a part per billion reading. To convert this to a Phosphate reading, divide the result by 1000 and then multiply by 3.066.
Coming in its own hard-shell storage case complete with battery, we found the packaging and components to be of excellent quality. The cuvette cap didn’t leak at all and the unit didn’t turn off unexpectedly during the test. It would have been nice to get more than the 6 packs of reagent to get going with but take note that refill packs are available (currently around £8 for 25 refills). Perhaps the use of small vials for the reagent powder would be better but this is not a major concern. If you are wondering what reading we got on our test tank, the unit came back with 10ppb which translates to 0.03ppm… not bad, but we could do better!
Our conclusion – this is the simplest test kit we’ve ever used and the definitive result given at such high accuracy is impressive. Retailing at around £55 this isn’t the cheapest option but out of the current crop of kits pitched at hobbyist level, we think it is the simplest to use, most accurate and best value for money, particularly for those keeping sensitive, high value species.
Keep an eye on the blog for our forthcoming look at the Hanna Test Checker for Calcium.