In one week we are starting a new experiment. The setup for this experiment presents some challenges that require me to add some new skills to my resume. We are testing how the toxic metal nickel, when found in sediments (read: mud), affects the growth of a common freshwater amphipod. We'll be conducting this test in 160 small beakers in the lab. The trick to these tests is to make sure the water in the beakers stays clean throughout the test. Usually, we can accomplish this by exchanging the water daily, but that won't work for these tests. Nickel is very mobile and can "leak" out of the sediment and build up in the water, which potentially might cause problems for the amphipods. A previous study by some colleagues showed that if you change the water every three hours you can keep the water clean. We have very dedicated undergraduates that work in our lab but even I wouldn't expect them to come to the lab at 3 am to change water in 160 beakers!
The best option for frequent water changes is to use an electronically-controlled water dispensing system. I am sure we could have contacted an engineer to design such a system but our budget for this project is already stretched thin and paying for a professional system was not in the original budget. Thus, the task becomes do-it-yourself, which is not an uncommon phenomenon in our field. Thankfully, I have a brother who is an electrical engineer, and he gave me some free advice for designing and programming the system. We decided on a system that uses solenoid valves, which are normally closed but can be opened by passing an electric current through them. By connecting these valves to timers we can automatically program the valves to open at specific times and stay open for a sufficient amount of time to exchange the water.
The best option for frequent water changes is to use an electronically-controlled water dispensing system. I am sure we could have contacted an engineer to design such a system but our budget for this project is already stretched thin and paying for a professional system was not in the original budget. Thus, the task becomes do-it-yourself, which is not an uncommon phenomenon in our field. Thankfully, I have a brother who is an electrical engineer, and he gave me some free advice for designing and programming the system. We decided on a system that uses solenoid valves, which are normally closed but can be opened by passing an electric current through them. By connecting these valves to timers we can automatically program the valves to open at specific times and stay open for a sufficient amount of time to exchange the water.
Inevitably, what I naively assumed would be a relatively simple task turned out to be pretty complex. Choosing the right size solenoid valve required some hydrologic calculations and a bit of shopping around. We didn't want to have to buy a solenoid valve for each of the 160 beakers so we had to build splitters to evenly divide water from one solenoid valve to multiple beakers. I installed switches for manual control of the solenoids and a serious controller for the automatic program. Luckily, I completely relied on my brother for writing the automated program from the controller. All told, the system required 500 PVC fittings, 300 ft of wire, 50 ft of tubing, and quite a few hours of my time. Initial tests of the system show that it is working as intended and hopefully our water changes will run smoothly for our experiment.
In the end, setting up this single experiment required a basic understanding of plumbing, electrical, hydrology, and programming. As I said above, this is not an unusual situation for experimental ecologists. Much of the equipment we need cannot be purchased off the shelf or even out of specialty catalogs. Some of the equipment is passed down through the ages or can be built from designs by others, but most of the time a particular experiment requires a significant time investment in tinkering, building, and adapting. The difficulty in designing and building equipment is a relatively invisible facet of an experiment that is often downplayed in presentations and publications. Anyone who has tried to replicate an experimental apparatus is likely well aware of the missing details about equipment; however, most of the time the people that initially designed an experiment and the necessary equipment are more than willing to help. In the end I think all the effort is worth it because well-designed equipment leads to better experiments, which generates better data and advances our science.
In the end, setting up this single experiment required a basic understanding of plumbing, electrical, hydrology, and programming. As I said above, this is not an unusual situation for experimental ecologists. Much of the equipment we need cannot be purchased off the shelf or even out of specialty catalogs. Some of the equipment is passed down through the ages or can be built from designs by others, but most of the time a particular experiment requires a significant time investment in tinkering, building, and adapting. The difficulty in designing and building equipment is a relatively invisible facet of an experiment that is often downplayed in presentations and publications. Anyone who has tried to replicate an experimental apparatus is likely well aware of the missing details about equipment; however, most of the time the people that initially designed an experiment and the necessary equipment are more than willing to help. In the end I think all the effort is worth it because well-designed equipment leads to better experiments, which generates better data and advances our science.