Fish that can be easily grown in the back yard:
Use a low speed, low wind, windmill to pump the water
Aeration: One low tech solution is a constant flow of water, from elevated storage tank or solar panels, down into the pond. I can add a small splash shield to keep spray off the insulative cover or just to keep it in the pond. The thing is, even if power, etc... fails, that water will keep going for as long as the roof mounted storage tank lasts. I'll probably add some standard air pump type aerators as well, but he water fall will A) look nice and B) provide very reliable O2 and C) the bubbles comming back up can be used to rotate a bio-wheel.
AgPals says "Microbes prefer 7.5ph. Plant happy medium at 6.5. Set pH at 7 for max compromise"
Avocado in hydroponics: 3' container, drain, gravel in bottom, sand on top, drip. Lower roots are structure and holding, upper roots are feeder. Keep lower dry, upper wet.
In the greenwater system some nutrients are recycled back to the fish. The vertical-lift pump and air stones keep detritus, feces and plankton in constant circulation. Nitrifying bacteria (Nitrosomonas and Nitrobacter spp.) colonize this floating "substrate" creating a "suspended growth treatment process". These bacteria oxidize toxic total ammonia nitrogen (TAN) into relatively harmless nitrate (NO3-) and heterotrophic bacteria (bacteria that consume organic matter) proliferate. The suspended growth treatment process maintains adequate water quality for the fish while recycling waste nutrients into plankton and bacteria. Tilapia graze on these and receive supplemental nutrition, thus lowering feed conversion ratios and feed costs. An added advantage of this process is the elimination of the need for a fixed-film biofilter, which would not only increase capital costs but also increase management and maintenance needs.
[The water is circulated through a clarifier once each 24 hours.] As the water moves under the baffles within the clarifier, its flow becomes laminar, enabling detritus, feces and dead algal and bacterial cells to settle to the bottom. Twice daily this sludge is drained from the clarifier and used as plant fertalizer reducing the biochemical oxygen demand (BOD) of the culture water and encouraging continued algae and bacterial population growth, which further improves water quality.
Caution: In the event of [an airation failure], all of the fish in the system would asphyxiate within hours. This is because the suspended growth treatment process creates a very high BOD. Overfed algae grow wildly. When they die and decay, [the bacteria which consume them] use oxygen.
"...for a liner, I learned of a product called a 'silo cap.' Found at any farm store..." Yeah right. I'll be damned if I can find it. +Possible sources of liners:
James Newton Says:
The fish pond is starting to take shape. I found a graded lot near work were I can steal rocks pretty safely, and I hit uppon the idea of driving wood stakes (firewood) into the ground between my bolders to help support the smaller rocks. Then I've backed up the rocks with sod cut from the area inside the pond so that the inner wall looks sort of like a vertical lawn at the moment. Its sort of like adobe (I hope) and seems to be holding so far.
Finally filled it this last Saturday: 2004/07/10. Many thanks to Erich Wolfe and Jeff Mullens (?) for helping to spread, fill and finish the liner. Sadly, I couldn't find batteries for the power sucker I call a digital camera until after we had spread and started to fill the liner, so it is a bit hard to see what the inside looked like before we laid it out. There is a nice layer of scrap cardboard and soft play sand under it. All rocks, sticks, shards or anthing else that might puncture the liner has been removed.
Still need to:
- Figure out how to hid that last bit of liner
- Add more rock around the lip (Recieved some free slate from a nice family via the sdfreecycle so that might help)
- Plant some water plants and get mosquitoe control fish in place.
- Get the kids to pick up the back yard and STOP SPLASHING ABOUT IN MY POND!
James Newton replies: One week later, mosquitoe larve started to show up so I got some of the mosquitoe eaters from the San Diego County Dept. of Environmental Health and they seem to be doing fine. We thought they had been eaten by the next day, but it turns out they are just REALLY good at hiding.
Starting to get the first "blooms" of algea so the water gets cloudy then clears up, then does it again.
Also got some floating plants from the San Diego Water Garden meeting. A VERY kind and giving host opened his home (and life) to more questions (from my 7 year old), pokes, proding and soda spilling than he probably wanted. THANK YOU!+
James Newton replies: Erich Wolf sent on some floating plants and a few more fish. All the plants seem to be getting a bit much sun, but are holding their own. The fish are breeding, eating, and loving life.
Debra, a nice local bunny lady, donated a stone sink which I will setup as a cistern for the "poopy" water siphoned from the lowest point in the pond. I have to find a way to seal it since it does leak a bit. +
James Newton Says:
The plants don't seem to have done all that well... the heat followed by cold snaps this winter have all but done them in. The mosquitoe eaters have done well, but spend most of thier time quiet and deep when the temperature drops. The bottom of the pond is at 42' and steady while to top varies from 44 to 65 with the air temperature from 50 to 80.+
Some form of insulation (perhaps a good plant layer? or floating bubblewrap?) is going to be required along with heating if there is any hope of growing talapia.
A local "going out of business" sale at a place that does water filters yealded two pumps for $25 each and I "dummied" up a bamboo flue from the roof of the porch out over the pond. The resulting drop is about 6 feet and provides more than enough aeration with only a very little "splatter" so I don't think water loss will be a problem. The pump draws 75 watts so that is no more than a standard lightbulb. I'd rather use wind power, but the pump will be an acceptable alternative and a good backup when the air is still at night.
James Newton Says:
The summer of 2005 has passed with the plants doing a bit better than last summer since the lovely peach tree we planted between the pond and the west fence is providing a bit of shade. We added two lilly plants which have been blooming very nicely. We did have some aphids on the pads, but I just push the pads under watter and the fish go nuts clearing the bugs off.+
I've finalized the bamboo flue with about a 3 foot drop and that seems to do well for both aerating and circulating the water through the cistern. The algea grows nicely in the bottom half of the cistern and accumulates the "fish poop" and so on under it. I pull the algea to the side and scoop out the "black water" from time to time for the garden and fruit trees. I plan to add some media for the algea to grow into inorder to clean the water a little more.
The pump and siphon have been unreliable. Somehow, air always seems to get into the tubing or algea clogs it. I put a loop in the hose on the outlet of the pump and ran it up the side of the fence and back down to the flume. Then I added a cheap timer to turn the pump on and off every half hour. When the pump turns off, the water rushes back down the outlet hose, through the pump, and flushes out the inlet removing debris and air. This has improved the system, but it still requires flushing out every few weeks.
I've added a small air pump and stone bubbler to increase the aeration and fill in for possible failures of the pump / flume during the summer when the water is warm and O2 levels are likely to be critically low. So far, the mosquitoe eaters and the goldfish are doing fine, getting fat.
Another problem is that although the sloping sides of the pond do a great job of collecting gunk in the center, the plants also grow out of the center so scraping out the gunk kills all the plants. A better design would be a series of steps doing down so that the plants don't all slide to the center and some can be kept in pots below the surface. I think the gunk would still make it to the center bottom and then could be scraped out, killing only the plants that rooted in that deepest water.
Talapia next spring!
James Newton Says:
Spring of 2006 brings a pair of blue talapia to the little pond. They are hard to see, but have been spotted on one or two occasions throught the summer. They are not large, perhaps 2 inches long, and we do not expect to fill our tummies with them any time soon. As fall approaches, my biggest concern is how to winter them. I don't want to waste electricity heating the pond so I am looking into providing some sort of solar hot water heating. Perhaps coiling the pump outlet hose on a black surface in the sun. The problem there is finding any sun in the area around the pond. I also have two large solar water heating panels, but installing them will be quite a bit of work and again, finding a place is a challenge. If you start on a pond, think more about the path of the sun than I did.+
James Newton Says:
The talapia died as soon as the temperature dropped out of the 80's. I'm adding a solar panel to try to raise the temp, but I think I will need to concentrate on other fish that are more appropriate for the temperatures.
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