This page is the open source and free-shared design and construction page for the Duplicable City Center natural indoor/outdoor swimming pool and eco-spa. This page will continue to evolve until it includes complete open source and free-shared county approved comprehensive building plans, purchase orders, construction instructions, editable CAD downloads and Sketchup files, construction tips and tricks, maintenance details, and all other needed specifics for duplication and care of this natural pool and eco-spa as parts of the Duplicable City Center or as stand-alone components.
After that it will evolve even further through global collaboration and sharing the evolutions and adaptations of other people’s projects using these templates and plans. This page includes the following sections:
A natural pool is a pool that functions safely without the use of chemicals; in this case, using ozone, germicidal UV, bio filters, and Hayward sand filters utilizing recycled glass to maintain clean and healthy water. An eco-spa is a hot tub designed to function safely with the minimal use of chemicals; in this case using ozone to minimize chlorine use. Some of the key features and intentions for the Duplicable City Center natural pool and eco-spa designs include:
* We will install a chlorine-feeder for emergency situations and will utilize an ORP meter to gauge safety. The chlorine feeder and ORP meter will allow this design to meet code is almost any county. This statement from Del Ozone leads us to believe chlorine will never be needed: “The Solar Eclipse uses DEL’s proprietary Plasma Gap Ozone Technology (patent pending) combined with high output, low-pressure germicidal UV lamps to make a potent yet economical AOP system small enough for residential pools. This system takes advantage of one of the chemical reactions that create an Advanced Oxidation Process: ozone irradiated by UV light in the 254 nanometer wavelength produces hydroxyl free radicals”
We want to inspire more people to build natural swimming pools and eco hot tubs. We’re doing this because it supports healthier people and a healthier planet and we know that open source sharing these designs, the permitting process, the building process, the safety-testing process, maintenance, and all the specific benefits of a pool and hot tub like this will hold huge value to a broad diversity of people. Additionally, we know if we make these designs easy enough, attractive enough, and provide enough of the foundations to also make them affordable enough, then the other benefits will promote themselves and help more and more people to start investing in this more sustainable option. As part of One Community’s global-change methodology, we see this as having the potential to produce an entirely new mainstream interest in these kinds of designs and all the benefits they provide, growing and promoting the entire industry and all people and businesses associated with it.
Da Ku: Mechanical Engineer
Jennifer Engelmeier: Eco-pool and Spa Equipment Specialist
Meg West: Landscape Architect, Permaculturalist, and founder of Meg West Design
Rick Ruggles: Swimming Pool Equipment and Health Consultant with Hayward Pool Products
Rob Gjerde: Swimming Pool Design & Construction Expert and owner of Sorico Design and Consulting
Here is the plumbing layout and plan for the natural pool. They include optional solar collectors for passive water heating assistance, natural filtration, backup chemical sterilization, and pump system with a heater bypass valve that will allow for bypassing the outdoor sections of the pool for winter energy savings:
Here is the plumbing layout and plan for the eco spa that includes sharing a heater with the pool and optional solar collectors for passive water heating assistance:
Purchasing details for all components are being assembled now. Here begins the list of equipment we are specifying for what we believe will be the safest, most eco-friendly pool on the planet. Also, with this pool and associated equipment package purposed to meet code anywhere in the US for this particular size pool and spa, The equipment that’s being recommended can also be easily scaled up or down depending on the actual pool size.
This is what the equipment listed here is sized for:
Here are the equipment specifics that have been selected thus far – rationale for selection is below:
It should be noted that the idea of a truly chemical free pool, that gets used regularly and is permitted in a commercial environment, is not a complete reality with the technology that exists today. Code in most areas requires adequate sanitization as well as backup sanitization. UV/Ozone and Ionization are good “alternative” sanitizers, although not without their own health concerns and controversy. But neither have a significant residual effect (ionization has a slight residual effect, but it takes so long to kill microorganisms that disease can easily spread). Chlorine, with all its controversy, is still the best sanitizer for killing microorganisms in the pool because it is both fast acting and has residual effects.
So our goal is to make this a potentially chemically free pool by connecting the chemical controllers, listed below, to the UV/Ozone/Ionizer as the primary sanitizer. The chemical controller would only inject small amounts of heavily diluted chlorine as a secondary backup safety system when contaminates enter the water that the “alternative” sanitizing unit can’t handle in a timely fashion. This way we will:
Also, the chemical control unit will constantly measure the pH, and adjust it down to our set point using, ideally, a liquid acid feed pump and tank, with heavily diluted muriatic acid. There are several reason why these chemicals are important in adjusting and stabilizing pH. First is the pH of a human eye is about 7.4, eye drops are usually about 7.5, and anything above or below will likely result in eye irritation. Second, even though the plan will be to not use much chlorine, it is pH dependent, and the closer to neutral the more effective it becomes by significant logarithmic jumps, so if we make what little chlorine we use more effective we will use much less. Plus, what little chlorine that does get introduced into the pool will have a short half-life with the UV generator and the sun.
With all this in mind, here are more specifics on the best equipment set we’ve come up with to balance energy efficiency, effectiveness, safety, ease of maintenance, and chemical consumption:
Here are the pump selections and capabilities:
Pool: Hayward EcoStar SP3400VSP SVRS Variable Speed Pump – EcoStarC variable speed pump with built-in SVRS – 3 years parts & labor
Assuming that the plumbing is hydraulically efficient, and that there is 40’ of TDH or less ( TDH is the total dynamic head – the total equivalent height that a fluid is to be pumped, taking into account friction losses in the pipe), this pump can be set to operate at 2000 RPM’s (60%) (approx. 48 GPM) and would turn this size pool over 4 times per day and consume 343 watts/hour.
Spa: Hayward EcoStar SP3400VSP SVRS Variable Speed Pump – EcoStarC variable speed pump with built-in SVRS – 3 years parts & labor
Assuming that the plumbing is hydraulically efficient, and that there is 40’ of TDH or less, this pump can be set to operate at 3000 RPM’s (87%) (approx. 130 GPM) and would turn this size spa over 100 times per day and consume 1,545 watts/hour.
To meet code, the spa will need to turn over at least 48 times per day, which means that the speed could be turned down considerably, which would consume less energy, and the speeds can be increased with 4 programmable speed options. However, these speed buttons are rarely used in most commercial setting because to change the speeds requires one to enter a password every time. This would be acceptable in a community setting such as ours though, as long as everyone agreed not to change any programming with the password.
The same filter will go on each body of water.
Hayward Commercial Sand Filter HCF363T(F) – 36”, 1,050 lb., 36-144 GPM – 5 years parts & labor
This is a sand filter, but we’ll replace the sand with a Zeobrite Sand Alternative. The filtration rate of this sand alternative raises to approximately 3 microns, where sand only filters down to between 20-40 microns. Here’s an overview of the eco-benefits of this choice:
The only drawback of Zeobrite, is that backwashing periodically is required and this adds to water consumption.
Depending on needs, options, and money, the following units will work for each body of water. All of the following control primary and secondary sanitization systems as well as pH. All of the CAT controllers include a 5-year limited warranty on controller and 2-year on the sensors. The HCC controller has a 1 yr. warranty on controller with factory labor.
Hayward CAT 4000 Automated Chemical Feeder (WI-FI) – Communicates anywhere in the world via Wi-Fi. Remotely control and view water chemistry through apps or web, receive alarms indicating problems. Web-based management requires monthly subscription
The primary sanitizer we’re looking at for each body of water is from Cambell Environmental Systems
Two Stenner tanks, with attached chemical feed pumps, for each body of water. One housing diluted liquid chlorine and the other diluted liquid acid. 1 year warranty on tanks and chemical pumps
Solar Breeze robotic surface cleaner
Note: Not normally recommended for a commercial pool because it would get stolen
Tiger Shark Plus RC9955 robotic cleaner
POOL: Hayward CrystaLogic LED Light for Pool (including Niche and 300W Transformer)
SPA: Hayward CrystaLogic LED Light for Spa (including Niche)
Accent lights: 12v LED, 320 lumens
Pool inlet fittings: 4-5 return inlets from the following 2 models specifically designed for low-flow pools to dramatically improve circulation
As shown above, the actual swimming pool is an indoor/outdoor pool. Below are two the design plans for the transition point.
Here is a design plan for a door structured to be able to be closed anytime it would be beneficial. Examples of when this might be desirable would be insulation in the winter, sound control when events are being hosted inside or outside, and separation of the swimming areas whenever needed. Da Ku‘s heat loss calculations for this design in a worst case scenario (subzero outdoor temperatures) is around 325W, which is the energy lost per second, for a total evening energy heat loss of around 4kWh, or 0.014 MMBtu.
Door, Frame, Door & Frame – Click to Enlarge
The price for a 0.5” thick, 35” * 75” plexiglass is around $261, we need two of them, so $522 (source). The gasket we’d need is around 740 inches, so total cost is around $99 (source). Continuous hinges cost $26.50 each and we need 4 for a total of $106 (source).
Transition design #2 is two underwater openings, one for movement out of the building and one for movement into the building. This is what we are planning now because of its benefits for the City Center HVAC design. By using two below-water openings through the 6″-thick wall instead of a door, we’ll be able to eliminate the “constant open window” affect that the door would create whenever it isn’t seasonally closed. An opening like this will still be able to be sealed in the winter months while providing much better insulation efficiency during the rest of the year. Two openings will also be safer than one by having a separate opening for movement in each direction.
Design details are coming….
Approximate energy consumption for this pool, designed splitting the pool at the indoor/outdoor transition point so we can close that transition point in the winter and still keep the pool healthy and beautiful. This requires double the equipment for the pool. Also, some health departments will require an actual presence of chlorine, some will make exceptions, and some realize that ORP is a true measurement of water quality and safety. For this reason, we’ll have the ability to add chlorine to make them happy while removing it whenever our ongoing pool water testing shows it’s not needed.
3 EcoStars variable speed pump (2 – pool, 1 – spa)
Max energy draw (100%, 3450 RPM’s) 2,326 WATTs per pump
Estimated pump use:
3 – CAT 4000’s (15AMP, 120 VAC) approximately 1,800 WATTs (when/if all chemical pumps are operating
2 – Universal Crystal Logic pool lights (14v, 5amp) – approximately 70 WATTs
1 – Universal Crystal Logic spa light (14v, 2.5amp) – approximately 35 WATTs
Here is a list of water purifying plants under consideration for growing in these natural pools. This list is from the book Growing Clean Water by Bill and John Wolverton and purposed for the most extreme water purification situations:
In the book it is suggest to feed the plants to keep them producing. When a plant is full of contaminants (we’re not yet clear on how the average person would be able to determine this), disposal and replacement of the plant is suggested through composting (for non-food use) or burning.
This section will also continue to expand and eventually include complete permitted plans, downloadable 3-D Sketchup and CAD files, instructional videos covering the entire building process, complete maintenance and upkeep details and instructions, and more. Visit our Helping Page for details on how anyone can assist us in making all of this happen faster.
Natural swimming pools and eco hot tubs provide a healthier and more sustainable pool and hot tub environment. This page is the process of open source sharing a chemical-free pool and minimal-chemical hot tub complete with designs and plans, the permitting process, the building process, the safety-testing process, maintenance, and all the specific benefits. We are doing this as part of One Community’s global-change methodology to inspire a new generation of people to build like this and experience all the benefits for themselves and the planet so we can significantly support, forward, and accelerate the mainstream interest, implementation, and further development of these technologies.
Q: Has a truly natural commercial pool ever been built in the US?
Yes! Here it is and it is beautiful! Check it out: Webber Park Natural Swimming Pool
If you have a question you’d like answered here, please contact us so we can add it and make this page better.