cob--- Aquaponics/swimming pond inside house

Has anyone built their aquaponics pool inside the house using cob walls lined with EPDM rubber liner?  Here's a brief rundown of what I'm thinking. I'd welcome input from others who have thoughts on building fish ponds within their living space.

    Since I am building with a slab on grade and weight bearing is not an issue, I figure it should be possible to construct the shape of my tanks from cob. The plan would include one course of concrete block against the floor so that any spillage will not soften the base of my wall. The fish and swimming ponds would be located in a greenhouse area built along my southern wall. This would maximize solar gain so that my tanks become my thermal flywheel. The floor of this area will be set one step below the rest of the house. This is to ensure that any sort of minor catastrophe will not be able to flow into the main living area of the house.

    To avoid overheating the home in summer there will be several patio doors leading outside which can be left open. The greenhouse will be easily separated from the rest of the house with several more patio doors and sliding glass walls along with thermal curtains. Recycled patio doors are worth $25 each to me so the cost is minimal.

    My thermal mass heater and hot water storage will be built into a Trombe wall immediately north of the ponds and hot tub. This will allow me to use this heat source in addition to the hot tub heater.

    I'm looking to create a recreational area that includes swimming and hot tubing without the use of chemicals. My hot tub will be woodfired by a rocket stove so I'll control bacteria simply by orchestrating large temperature swings. The tub will be fired well beyond the comfort zone in advance of its use. Since everything is within the heated space of the house no energy is lost because the cooling water heats up the house. If the tub is still too hot when it's time to use it I'll pump water from the swimming area until things are just right. An overflow will send excess water back to the pool. When a heated pool is desired the hot tub will emptied by gravity into the pool. The pool will be built large enough to accommodate 500 extra gallons whenever this is done.

    Immediately to the south of the house will be an outdoor swimming area. In my climate it's likely to be useful from May through October. I'm on a south facing slope in a very warm microclimate and will use solar blankets and heaters to extend the swimming season.        The indoor and outdoor swimming areas will be connected by a six-foot channel so that you can swim from the living room to the gardens outside . A small portion of this channel will be made of concrete and during the winter in this area I will place an insulated weir made from that dense blue foam material that insulates concrete foundations. This will provide a good thermal separation between indoor and outdoor ponds.

    Since I get paid to dispose of obsolete hot tubs I may incorporate a few of them in the ponds and or filtration system. Usually when people are scrapping a hot tub the fiberglass tub itself is fine but all the pumps and jets, heaters etc. are in need of costly work. I will simply remove those things and place fiberglass patches over all of the openings.

    When the pool overflows it will dump into an aquaponics pond. Graywater from the house will go through a sand filter and then it will also dump into the fish tank. Overflow from the fish tank will flow to a wetland area outside the house. This wetland will contain edible and decorative plants and may also contain some outdoor fish. A sort of floating hugelculture bed will sit atop a few hundred square feet of sand filter.

    There is no shortage of water on the property at any time of the year( Vancouver island) so I'm not going to recycle the effluent for domestic use. Instead it will be used for outdoor irrigation or when not needed for that will be allowed to percolate into my gravelly soil. Although the land is reasonably flat it drops off immediately in front of the house and plummets 150 feet to the river flats. So drainage will never be an issue. During our wet season I can drive a pickup truck to any point on the property without the worry of getting stuck . Although this soil is gravelly it produces huge Douglas firs and other growth.

I love the concept, looks very ambitious!  Are you planning to recirculate the water at all through the system or does it go in a line from indoor swimming area through the pond to the edible wetland?  If it does not recirculate, what are your plans for stabilizing pH for the fish?  Or will the swimming pool water be only a minor addition to a much larger outddor pond?

Hi Dale
Knew a guy that built his house over a swimming pool. He heated with wood, pool kept temps more constant. Not quite what your talking about but the place stands out in my memory due the fact that when you visited him he often would jump of couch into pool just because he could. 

I would be a bit concerned about having so much moisture in the house. If the water gets warm it evapourates. There's a reason why you always open the window after showering.

    The fish pond section will be separate from the swimming area. None of the hot tub or swimming water will be treated with anything other than heat so there's no danger of contaminating the fish. Usually new water from the well will fill the hot tub and overflow will be used for irrigation etc.. With no shortage of water there's little need to recirculate. As for pH, I'll see if that's a problem and deal with it using limestone or what ever works. The indoor fish area will be a small overwintering area of about 1000 ft.³ of water. The outdoor pond will be considerably larger so I suppose indoor water could be mixed with outdoor water if this tends to solve any water chemistry issues.

  As for adding too much moisture to the house the ponds will all be within the attached greenhouse and separated from the rest of the house with glass walls and patio doors so they shouldn't add any more water to the house than what is desired. A small bay will protrude into the living room but this will be an area of only 35 ft.² and it will have a cover. It's a living room diving area .  A sliding door opens up in the wall and a hinged cover is flipped to vertical and held with a hook. Presto, the living room is now poolside. If little children visit, the door and hatch will be closed.

    My permit allows me to have four bed-and-breakfast units so I'm throwing in things like living room swim area as a draw card to include in my advertising. I'm also going to have a small Treetop walk, unique rocket stoves and other useful though somewhat gimmicky accessories to help with marketing.

Personally I think it would be fabulous to connect the swimming and fish ponds, even if the fish aren't allowed to swim with the people, and recirculate the water through edible plant grow beds  and water plant beds.

I have a wild dream to construct an aquaponics swimming pond, but it won't have an indoor component. 

http://www.motherearthnews.com/Do-It-Yourself/2002-08-01/Natural-Swimming-Pool.aspx

http://www.thedailygreen.com/green-homes/latest/natural-swimming-pools-460908

Sounds like a great idea! I'd just be careful with how hot any EPDM liner may get.

You'll definitely need to use those doors quite a bit to control humidity. My indoor aquaponics system ended up causing big mold problems because I didn't control the humidity.

    Has anybody had success with whitewashing the portion of liner which protrudes from the water and wraps over the edge of tanks? This might prevent the liner from breaking down from sunlight and it would keep it cooler.  I've also thought of using some sort of sacrificial material which could be as simple as a 2 foot wide strip of the same lining material. This would prevent the liner which holds the water from experiencing UV degradation.

   I cleared trees from a spot where I'll put the wood fired hot tub inside a small greenhouse which is dug into a south facing bank. It's the hottest microclimate on my property.

If you want to swim in that water, especially if you want to rent this out you want to have 24°C. A 16°C  swimming pool wouldn't be a lot of a draw card. The warmer the water the bigger the moisture problem inside the living room and inside the glass house. I would ask and engineer who has ample experience in constructing public swimming pools. Two hours wouldn't cost that much but moisture problems are unhealthy and expensive.

    I'm simply not afraid of the moisture issue since I have plenty of experience in dealing with water both liquid and vapor and I'm designing the greenhouse portion so that it closes off completely from the house and acts as a separate greenhouse. Plenty of opening windows including high gable end units will promote airflow. I'll only open the greenhouse to the rest of the house when moisture is desired.

Dale, I personally have no experience with the kind of project you are talking about, but it sounds fabulous. I know that earthships often have indoor pools for gray water treatment, and fish and plants are grown. Might be some relevant experience there...

Sounds pretty cool.  So you're controlling the water quality of the spa with temperature, but what about the swimming pool?  How long can you leave the spa for without heating it up, before it gets nasty?  Would using a cover to exclude light completely when not in use be helpful in this regard?

Definitely recommend high level windows in your greenhouse, which will help evacuate warm air.  Maybe consider using something inexpensive and low tech like this product to automatically get ventilation when necessary.  This one opens at a slightly lower temperature than is probably optimal, but I'm sure similar products would be available that have a different setting or are adjustable.

http://www.amazon.com/Cold-Frame-Automatic-Opener-Arm/dp/B0007VLQC8/ref=sr_1_1?ie=UTF8&qid=1317183050&sr=8-1

The hot tub water will be regularly heated to a temperature high enough to kill algae and other life during the winter so the tub will be part of the heating system. If the water becomes stagnant or accumulates too much algae I'll drain and start over with  clean well or roof water. In the summer the tub will be drained regularity since it will be the first spot that irrigation water enters my system. Water which flows out of the hot tub will make it to the swimming area and then to the fish and from there it will move on for irrigation purposes. I have plenty of high-quality freshwater year round so conservation isn't really an issue.

    As for water quality in the swimming area I'm going to plant plenty of water lilies, irises and edible water loving plants in shallow bog areas to help remove nutrients. I may also go with some sort of pump and drain back system where I irrigate crops in a separate grow area. When I was a kid our pool was mostly pea soup green and we all survived unscathed. Basically if it's wet I'll swim in it. A simple sand filter built from an old culvert could be used to clarify the water. I'll only concern myself with water chemistry if an uncomfortable or unsightly problem develops. Problems like swimmers itch are generally related to waterfowl so I'm not going to have any ducks or geese near the swimming pond. In the summer I have the option of walking down the hill to one of the cleanest rivers you've ever seen so if indoor water quality deteriorates there's always that possibility. But in winter that river is much too cold and that's when I expect to get the most usage from the swimming pool.

   In the winter I have a very clean runoff ditch going through the culvert under my road. This is seasonal run off and not a fish bearing stream. It dries up completely in the spring. I've measured its flow at approximately 10 garbage cans per second so there's an unlimited water resource during our rainy winter season.

     The Nanaimo BC water district has a large water pipe which runs across my property.Every year during the dry season they do a flush to the system and millions of gallons of water are dumped into a swampy area between my property and the river. All of this water flows through my culvert so I plan to construct a pond which I'll top up when they do this.     Whenever I visit dry parched areas of the country I'm reminded of this resource.