About Us

The Story Behind the SAS

Whether you ended up here because of an interest in marine science, open-source design, or education and outreach, please take a second to read about our team, the SAS project, and how it came to be. an image

The Acidification, Climate, and Coral Reef Ecosystems Team (ACCRETE) at NOAA’s Atlantic Oceanographic and Meteorological Lab studies how changing ocean chemistry is impacting coral reef ecosystems. ACCRETE researcher Dr. Ian Enochs received a grant to design and build a water sampler to help further NOAA’s research goals, and also provide a low-cost alternative to existing sampling systems that could be made accessible to all interested parties. To support the open-source design of this new sub-surface automated water sampler (SAS) this website, along with detailed construction and operating guides, were created.

The cost to build one of these SAS is about $215, which is considerably less than existing water samplers. Many of the largest costs come from items like PVC, adhesives, and solder which are bought in bulk rather than single servings so, the more samplers built, the lower the individual cost. The simple design of the SAS also leaves room for easy modification depending on the user's needs, and the ACCRETE team intends to continue improving on the design to fulfill its own research needs.

The people behind the SAS

The SAS is the brainchild of Dr. Ian Enochs, thought up as a means of better studying the changing carbonate chemistry of seawater on coral reefs. Ian brought Nate Formel on to the ACCRETE team to help realize the design, prototyping, and production goals of the SAS project, and to lend his experience in coral research to ensure a functional tool was developed. Dr. Alan Piggot was also a crucial member of the team. Using his research and extensive teaching experience Al worked with Ian and Nate to develop outreach and education materials for the SAS, as well as create a website (this website) to enhance dissemination of the SAS open-source design.

How did we do it? Well, have you heard of the Engineering Design Process?

The Engineering Design Process (EDP) is essentially the scientific method adapted to engineering with some small differences. Without realizing it most of the time, the creation of the SAS followed the EDP almost organically. Take a look at how we overcame scientific and engineering challenges using the EDP to keep us moving forward:
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Ask "What was the motivation for making the water sampler?"

an image Oceanic uptake of rising atmospheric CO2 leads to a decrease in seawater pH and a reduction in the saturation state of calcium carbonate (Kleypas et al. 1999). This phenomenon, called ocean acidification (or OA for short), is currently occurring at a rate faster than in the past 300 million years (Hönisch et al. 2012). OA will detrimentally affect numerous marine ecosystems, including coral reefs that provide numerous goods and ecosystem services (Hoegh-Guldberg et al. 2007). While open ocean carbonate chemistry shows a clear trend in decreasing seawater pH, data from shallow-water systems are inherently more dynamic. The fluctuations in water chemistry in shallow water systems occur over time scales ranging from daily to seasonal. For this reasons, accurate, high-frequency sampling is necessary in order to characterize variability and monitor OA trends in these environmentally-sensitive and economically-important shallow-water ecosystems.

Ask "What were some of the design constraints for the water sampler?"

The issue of cost and time are the largest hurdles often faced in marine research so the objective of the SAS design is to overcome those issues making it easier to study carbonate chemistry on shallow reef habitat. This means we had to create something that could maximize our effectiveness in collecting OA data on coral reefs while minimizing our cost and time. To do this we needed a waterproof device that can reliably collect water samples as effectively as the current common practice (Dickson et al., 2007) while also enduring the often rough water conditions that occur on shallow nearshore reef habitat.

Generate Concepts "What was your prior experience with water samplers?"

an image Most of the water samples collected by the ACCRETE lab have been done manually by staff and other research groups in the field. Automated water samplers do exist, but their design is proprietary, adding an inflated cost to their use, typically unwieldy in size, limited to single samples, or just not functionally applicable to shallow water environments. In 2015 Dr. Enochs began developing his first iteration of a sub-surface automated sampler that could be deployed on the reef down to 15m depth to collect two 500mL water samples at pre-set times. This first design was a big step forward, but still a cost prohibitive option for many researchers (>$1,000 per sampler).

Generate Concepts "How does your team brainstorm ideas?"

an image an image The wealth of marine research experience in the ACCRETE lab has allowed us to sit down and throw ideas onto a whiteboard and parse out what we thought would work best. We return often to the whiteboard as a basic tool for examining design ideas to overcome obstacles before we move forward, and that visual can help quickly identify obvious benefits or pitfalls to a design. The open-source online community has also been a huge source of inspiration for ideas to build off. Websites like OpenROV.com and the Cave Pearl Project have been two excellent resources for helping us see what's already been done and build off of that instead of recreating the wheel. Having a physical prototype in hand to test out is the final step in searching for solutions to design issues. During the prototyping phase, multiple approaches to the same issue (e.g. how to make waterproof openings in the housing for the pumps) are typically created, tested, and compared, and then we move forward with our best most functional option that supports the project goals.

Develop a Solution "Walk us through an example of when you get a new idea for a design change, what is the plan or pathway to get it from an idea to a plan ready to execute?"

an image If there is going to be a new component built for the sampler or a complete design change to a current component, we typically model it on CAD software to have a virtual example of what the change is. If that seems to work, given our criteria from the design phase, we’ll 3D print the part and add it to our physical design and look for difficulties there by running the sampler, handling it, and exposing it to increased pressure in our pressure chamber. If it survives all these test and examinations it becomes the new norm.

Create "What technology(s) do you use to create your new idea or design adaptation?

The SAS is the first major project made possible by our new Advanced Manufacturing and Design Lab at NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML). We use a cloud-based CAD program to create the initial model of the components of the water sampler. From there we can send files to our stereolithography 3D printers, or laser cutter, to produce a prototype of each component. For the circuitry of the device we use an automated milling machine that can mill our double-sided circuit boards to the exact specifications that our engineering team needs. None of the technology is brand new, but a lot of it has only recently become affordable enough and compact enough for small scale prototyping. There's a learning curve that comes with using this technology, but the potential application to many of our areas of research makes the effort well worth it.

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Create "Describe the feeling of excitement of when you print that new idea and get to test it?

There’s always some excitement to be able to produce an idea that existed only in your head, and then hold it in your hand once the printer, or the laser cutter, or the mill has finished its job. With the excitement comes some trepidation too, "Will it work??" The answer isn’t always yes, but the failures are an important part of the prototyping process and we learn something from each of them, whether it’s the shortfalls of our design, or the limitations of our production ability.

Test "How does the team analyze and get feedback on a test to evaluate a prototype?

an image an image In the lab we carry out pressure testing of the sampler and “dry runs” of the equipment to evaluate the different features, like the flow rates of the pumps, battery life and function, data logging. To evaluate consistency of these functions replicates of each test are done, if possible, in varied conditions. One of the resources available to the lab through our collaboration with University of Miami’s Cooperative Institute for Marine and Atmospheric Studies (CIMAS) is an advanced wet lab system where the temperature and pH of the water in the experimental tanks can be controlled precisely. This experimental setting has allowed us to test the SAS prototypes in an even larger variety of conditions than they would experience naturally when deployed in the field, helping improve our confidence in their function. The results of the tests on the sampler features are quantified and evaluated to confirm consistent and accurate function. One of the intentions for the SAS is that it be easily deployable by a single diver, so deployment in the field by our research team has been a last but important step in our prototype testing process. The nature of the open-source project, however, is that the design will continue to be refined, even as we wrap up the SAS project, to maximize the utility of it as a tool and improve our capabilities as researchers.


·JA Kleypas et al. (1999). Geochemical Consequences of Increased Atmospheric Carbon Dioxide on Coral Reefs. SCIENCE. 02 April, 1999. Pp. 118-120.

·B Hönisch et al. (2012). The Geological Record of Ocean Acidification. SCIENCE. 02 March, 2012. Pp. 1058-1063.

·O Hoegh-Guldberg et al. (2007). Coral Reefs Under Rapid Climate Change and Ocean Acidification. SCIENCE. 14 December, 2007. Pp. 1737-1742.

·AG Dickson et al. (2007). Guide to Best Practices for Ocean CO2 Measurements. PICES Special Publication 3.