Most fish hatcheries run on steady supply of fresh water to keep the fry healthy and encourage fast growth, but this is a wasteful practice that depletes natural resources. Water reuse systems require an upfront investment, but when properly designed, they can save both money and resources in the long run. Consider these recommendations when planning the plumbing to connect all those filters and degassers to your raceways and tanks.
Focus on Flow
Adding all those extra steps in the water delivery system often requires the use of stronger pumps that produce higher pressure. However, those heavy duty pumps also increase your energy costs. If you're trying to cut costs while still implementing a complicated recycling system, proper plumbing design allows you to use the same low flow water pumps you already have on hand. These design tricks include
- Minimizing bends, U-turns, and other pinch points that reduce flow
- Choosing larger diameter pipes to keep the water moving on its own
- Running the plumbing down a slight slope as it runs across the facility to let gravity handle part of the work.
Many hatchery managers are concerned that adding a bunch of complex plumbing and water recycling equipment could increase the chances of back flow or other issues that contaminate the raceways with dirty water. In fact, a carefully designed and closed loop reuse program actually reduces the chances of disease and chemical exposure from the outside world. Work with an experienced commercial plumber to make sure connectors and funnel points are protected properly from reversed flow.
Plan Filter Overflows
Making the used hatchery water clean enough for pumping back into the raceways and tanks requires numerous filters, most of which spin or press solid waste out of the water before it goes on for more advanced cleaner. Any part of the system that accumulates solid waste has a chance to clog up and overflow. Instead of just hoping your cleaning and maintenance schedule will always prevent that from happening, add overflow routing and control into the plumbing system.
A simple overflow basin with its own separate drain prevents any of that contaminated water from splashing into the clean flow. Add in a sensor system that switches to a flow of fresh water for the downstream raceways when a filter shuts down, and your system will run smoothly without clogged filters causing sudden die-offs.
Of course, the placement of your new degassing towers and drum filters is limited by the space available in your facility. However, rearranging other equipment to make space for stacking components together can save you a lot of money on plumbing everything together. If you can connect a tower of filters and holding tanks with basic U-shaped connectors instead of running dozens of feet of pipe, you're taking advantage of gravity's flow and may be able to reduce the number of pumps you need throughout the facility. When everything's close together and stacked vertically, you can still use tight bends for short connections without interrupting the flow too much.
Add Freshwater Bypasses
Finally, don't forget about both manual and automatic emergency bypass connections to bring in a brand new flow of fresh water when something breaks down in the water reuse system. You don't want to lose a lot of delicate fry because the water stopped flowing for an hour or two. The plumber in charge of designing your reuse system can help you adjust your current fresh water pipes so they are easily re-purposed as emergency supplies instead of the main source. Even if you have to use the emergency fresh water flow a few times a month for hours at a time, you're still using drastically less water than before you installed a reuse system.
For more information about setting up a system like this, contact an industrial plumbing engineer.