Pond in greehouse?

I am planning a greenhouse for year round growing in zone 5- with plenty of cloudy days in winter.
It will likely be cedar framed (or pt, something slow to decay)as there will be poly attached to both the outside and inside for insulation. I don't like PT but any wood in a damp airlock will rot and I figure 100% safe from veggie contamination behind a layer of poly.

Goal is no electricity, just using alternative methods- including hardy winter plantings to extend growing season as far as possible.

Plan is approx 25' x 40', more or less. East to west.

The pond question is... any thoughts on whether and approx 3-3.5' deep pond, maybe 4' x 8' located centrally in the GH help significantly at all as a heat sink? A larger pond is of course possible so long as I can keep it productive enough to produce a similar amount of food as the soil crop displacement which I'm sure shouldn't be a problem.

Any ideas appreciated! Thanks.

Looks like you have frozen winters, which means dry winters... So, a form of natural humidification sounds to me to be a good idea

I would stock it with fathead minnow, duckweed, water hyacinth and one or two varieties of "sub aquatic" plants for oxygenizing the pond... The minnows with eat the mosquitoes (etc) and duckweed. Duckweed can be fed to livestock. Water hyacinth is an excellent composting material, and a rooting solution can be made with it!

how about a greenhouse in a pond?

http://vimeo.com/54217721

if the space permits a pond is a great idea..i've alwas loved enclosed swimming pools that are in a solarium type building..they are so cozy in the winter (when the water is heated esp)..

my little greenhouse has pex running under it from our wood furnace to our house..and our neighbors house..so it stays cozy in there in the winter.

sounds like a good idea to me. greenhouses frequently have humidity problems, and a pond may exacerbate them, but I would guess that a thoughtful design would prevent the issue.

Here's some math that I did last September in a thread concerning the ability of water and cob to store heat. It clearly shows that water is a great storage medium.-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Here are some very useful figures for anyone who is trying to choose whether or not to include a water tank within an RMH. Cob weighs 95 pounds per cubic foot. Water weighs 62 pounds per cubic foot. The heat capacity of cob is .2 which is 1/5 that of water which has a capacity of 1.00 So supposing we want to build a RMH which occupies 100 ft.³ of space.

First the cob - 100x95 equals 9500 pounds. 100 ft.³ of cob will weigh 9500 pounds. 9500x.2 equals 1900. So our cob bench has the same heat capacity as 1900 pounds of water.

Water weighs 62 pounds per cubic foot, therefore the tank containing 100 ft.³ of water weighs 6200 pounds

6200 divided by 1900 equals 3.26

A given volume of water can store 3.26 times as much heat as the same volume of cob.

Though I don't have Dale's aptitude for math, I can vouch for the heat-holding capacity of water.

Last year I put in my first greenhouse (just a simple frame with a single layer of greenhouse plastic). I was surprised by how incredibly hot it got during the day - and how cold at night. The fluctuations were ridiculous. The sun went down and BAM - it was COLD!

Then I did a little research and bought 8 used 55-gallon plastic drums, which I filled with water and placed in an orderly fashion inside my 10' x 20' greenhouse. The difference was startling - no more dipping below freezing at night, and no more high-heat during the day. The drums moderated everything wonderfully. Now if I forget to open the plastic door on a warm sunny day, the plants still won't cook... and on cold nights, they still stay frost-free.

Granted, I'm in North Florida - but the thermal mass was a big help. With what you're building, I think a pond would be quite nice.

Hello,
I am a relative newbe, so forgive me if my manners are poor. I have a question for Dale re heat capacity of cob. If this is not the place to ask this please let me know and I will repost. I was thinking others might like to know... Dale, do you know what the heat capacity of cob made with 1/3 pumice, 1/3 sand and 1/3 clay? Does the pumice raise or lower the heat capacity?
Thanks
love the idea of a pond in a green house. My old boyfriend had a pond in the kitchen. It was great.
Suzanne

Suzanne Cornell wrote:Hello,
I am a relative newbe, so forgive me if my manners are poor. I have a question for Dale re heat capacity of cob. If this is not the place to ask this please let me know and I will repost. I was thinking others might like to know... Dale, do you know what the heat capacity of cob made with 1/3 pumice, 1/3 sand and 1/3 clay? Does the pumice raise or lower the heat capacity?
Thanks
love the idea of a pond in a green house. My old boyfriend had a pond in the kitchen. It was great.
Suzanne

Suzanne, I think questions are totally acceptable and yours is well within the context of this topic. By dealing with it in the thread instead of as a private message, others may benefit or if I was to make some error, I'm sure it would be pointed out in short order.

--- It all has to do with weight. The vast majority of earthen materials have a rating of about .2 which is 1/5 that of water. With pumice, the density is lower, so there would be a drop in heat capacity per cubic foot. The capacity per pound is unchanged. This sounds like a mix that would come in at 70-75 lb per cubic foot as compared to regular cob at 95 lb.

Pumice has insulating properties and would affect the speed of heat absorption and transfer. For walls this is a definite positive. The story is different if the cob is for a RMH. It should slow heat transfer which may not be a desired result. Also with pumice there is a greater chance of encapsulating air. At regular temperatures, this would probably have no ill effect, but if the riser were cobbed over as is sometimes the case, this air could expand and cause an explosion. Not an A bomb explosion or even as powerful as a steam explosion, but still enough to do damage.

Dale,
I see your up in the wee hours also.
Thank you for the information. I was thinking of building with that mix, as I live in upstate NY and need insulation. I was wondering if it would slow the heat absorption in passive solar areas and the rocket stove. Thanks for answering my unasked question. ) I guess, i should keep the cob mixture on the outer half of the walls, and stick to traditional cob on the inside, especially on the bench/risers. Which brings up another question. Would the difference in weight cause the two different cobs to separate ? Would a gradual change in the mix in the walls keep that from happening? Now I've completely changed the course of this thread...

Suzanne Cornell wrote:Dale,
I see your up in the wee hours also.

It's three hours earlier in B.C. --- Considering the climate of upstate New York, you may wish to examine Light Straw Clay, Cordwood Cob, Papercrete and Straw Bale construction. All would be better suited to your climate. There's a lot of internet nonsense out there extoling the benefits of cob but ignoring its thermal limitations. Rob Roy lives in your area and has written a few books on cord wood construction.

If you've got to have cob, consider 6 inches of straw clay on the interior with an earthen plaster coating. Similar look but far superior,

With that, I think we're firmly off topic. Feel free to ask anything any time. Dale.

Suzanne Cornell is creating a new thread for pumice/cob

Im new here as well ..to post that is , however Ive been reading for years and im so excited that you have asked this question for I to am thinking of putting a pond in my green house (still in the planning.

Does bermed (terraced planting beds) earth have the same ability to give off heat as cob?

I live in Oklahoma...and as you know we are always challenged when it comes to gardening..LOL Ive been exhaustively researching these ideas about 365 gardening and preserving while living off of the grid, so before I call out the earth movers I want to make sure i have all of my ducks in a row!.....I was very interested in this site... http://greenhouse.taroandti.com/2008/02/28/earth-sheltered-pit-greenhouse/ It seems they are doing a hybrid type at a low cost.
I would love to find others in my area that might have some experience with this and i also have a few questions for the forum?.....

1. I notice everyone is planting on the floor. Wouldn't it be better use of the space to do a terraced planting along the walls and this would act as a berm as well?

2. Although i am knee deep into self efficiency My moto is( purposeful can be pretty at the same time)... So has anyone added some of the more aesthetic details to their plans... ponds, decorative elements ect?

3. could i figure out a way to incorporate a tropical zone for figs and citrus .. a zone where i could let plants go dormant if need be... a cactus area... a fish pond/aquaponic area and a little mushroom area? or am i looking at digging several different houses?

I was thinking of this just the other week. In fact I went so far as to put a design together so here some features if anyone is interested.

I live in zone 3 so I planned a half dome tunnel shape using a solid cob wall (on the North side) with compost bays in it that provide heating through the winter.
The thermal mass is provided by a 3 meter diameter, 1.2 meter deep fish tank that is partially buried in the ground.
The grow beds act as filter beds for the tank and I intend to put trout in the tanks.
The dome is made from a double plastic skin with the void filled with soap bubbles for insulation at night.
Above the tank is a mezzanine type floor which will hold the chickens over winter.
On top and next to the compost bays, are areas for seed raising, worm farm, bee hive, insect farms for fish and chicken feed, fish smoker and control systems for the bubble insulation, ventilation, power, and pumping.

Nick Kitchener wrote:
On top and next to the compost bays, are areas for seed raising, worm farm, bee hive, insect farms for fish and chicken feed, fish smoker and control systems for the bubble insulation, ventilation, power, and pumping.

I recommend against putting a beehive in a greenhouse. keeping the bees warm keeps them active when nectar and pollen sources are absent. unless the planned greenhouse is truly enormous, plants inside it could only provide a small fraction of food necessary to support an active honey bee colony. cold weather signals the colony that it's time for winter dormancy. some insulation of a hive isn't a problem, but putting them in a warmer-than-ambient environment is.

otherwise, your ideas are interesting and ambitious. I do hope you post about your progress when you get started.

Thanks for the recommendation. I thought bees started heating their hives (and consuming more energy in the process) below 55 degrees. I would not expect the greenhouse to be much warmer than that. It's between 0 and 12 degrees for 4 months of the year.

Nick Kitchener wrote:Thanks for the recommendation. I thought bees started heating their hives (and consuming more energy in the process) below 55 degrees. I would not expect the greenhouse to be much warmer than that. It's between 0 and 12 degrees for 4 months of the year.

sort of. they consume more energy for heating purposes, but less overall because they're largely inactive. if they're in a warm-ish greenhouse, they'll head out looking for forage that isn't there instead of maintaining a low energy winter stupor. they're also likely to get chilled outside the hive and die.

if the greenhouse is cool enough to keep them clustered, they'll be alright in the winter, but spring and fall would still cause problems. the bees would be active later than forage is available and temperatures are high enough for flight in the fall, and earlier than appropriate in the spring.

again, some steps to keep them warmer can be helpful, but it's easy to overdo it.

Kellybell hartley wrote:

1. I notice everyone is planting on the floor. Wouldn't it be better use of the space to do a terraced planting along the walls and this would act as a berm as well?

2. Although i am knee deep into self efficiency My moto is( purposeful can be pretty at the same time)... So has anyone added some of the more aesthetic details to their plans... ponds, decorative elements ect?

3. could i figure out a way to incorporate a tropical zone for figs and citrus .. a zone where i could let plants go dormant if need be... a cactus area... a fish pond/aquaponic area and a little mushroom area? or am i looking at digging several different houses?

Here are some comments based on my own experiences:

I have a greenhouse that has about an 8 inch "pit" inside, that is the floor of the greenhouse is about 8 inches below the bottom of the walls.
The reason I built the greenhouse originally was to protect two Satsuma mandarin trees during the winter. These trees are planted directly into the ground
inside. I planted directly into the ground because it will keep the roots from freezing in winter, but also allow the roots to roam where ever they want.

I'm not sure what you meant by "terraced planting along the walls"?

As for "decorative / purposeful" I also laid flat stones over the majority of the floor- this makes it more attractive and cleaner to walk on, but my major reason was for the stones to act as passive heat storage / moderation. I hung some Christmas lights in there last year, looked real weird from the outside on frosty nights.

This year I put some potted plants and trees in there also (whereas in previous years it was strictly for the mandarin trees)
This year I also planted a kumquat tree, a few tomato plants and a few chili pepper plants in the ground inside as an experiment.

I am so grateful for your input! Im in the planning stages of our greenhouse and to be honest we have way more problems with heat @ 100-114F for weeks this summer.. and a record drought. as for the few very cold days I plan on using a rocket heater and other passive solar heating in the design..Is anyone getting good results with any type of passive cooling system?

I have been researching the thermo mass heating and cooling qualities of Phase Change materials such as soy, paraffin and various salts encapsulated and placed on the north wall...

Cedar wood is great, or consider galvanized steel. Pressure treated lumber is toxic and not what you want in a food producing space. All that water that rots untreated lumber is still going to go into your treated lumber and then leach out toxins. You are guaranteed holes in the poly and condensation between the layers that drips down onto the PT wood. A single layer of poly is no protection from the toxins.

In cold climates, you're going to need 3 gallons of water per square foot to prevent freezing in a freestanding structure. So a 1000 sq ft greenhouse might need 3000 gallons. Your "pond" would have to be mostly above ground for all that thermal mass to enter into the equation. You can do container gardening on top of barrels, tanks, or part of the pond so you don't lose so much growing space.

So much good info here, thanks for all the help and ideas!
Where to start...

Pat, regarding the 3 gallons of water per square foot. Do you remember where you found that info? That's a great starting point for my planning stage- I am still sketching layout. I was planning to have the pond go fairly deep as we have a high water table meaning the bottom of the pond could be in contact with "warm" unfrozen water below the pond. That should be a huge benefit yet you are surely correct that the pond needs to be mainly above ground for any effect. I need to search pond construction and see what economical options would be. With your calculation I would need over 3000 gallons, bigger than any stock tank I've ever come across. Custom!

D Taylor wrote:So much good info here, thanks for all the help and ideas!
Where to start...

Pat, regarding the 3 gallons of water per square foot. Do you remember where you found that info?

I think I read that in Greenhouse Gardener's Companion by Shane Smith. Great book, but non-technical when it comes to thermal mass.

We raised red claw crayfish in our old greenhouse.

Redclaws can grow with other fish if the tank is warm enough. They like it tropical warm and grow to be about large shrimp to small lobster size.

They multiple like crazy with 3 hatches of 500 per hatch a year....so I would have to say is the biggest problem with them is making enough space for them!

Kellybell hartley wrote:Is anyone getting good results with any type of passive cooling system?

I have been researching the thermo mass heating and cooling qualities of Phase Change materials such as soy, paraffin and various salts encapsulated and placed on the north wall...

First and foremost, before active cooling with fancy systems, consider how to open your greenhouse glazing as much as possible in the summer. We use removeable plastic film, so we attach it to our houses in October and roll it up in April, and it stays out of the way rolled up under the eaves all summer.

Rebecca Norman wrote:

Kellybell hartley wrote:Is anyone getting good results with any type of passive cooling system?

I have been researching the thermo mass heating and cooling qualities of Phase Change materials such as soy, paraffin and various salts encapsulated and placed on the north wall...

First and foremost, before active cooling with fancy systems, consider how to open your greenhouse glazing as much as possible in the summer. We use removeable plastic film, so we attach it to our houses in October and roll it up in April, and it stays out of the way rolled up under the eaves all summer.

Oooo!. I'm planning my greenhouse as an extension to the southerly side of my house and will be running the plastic from the house eaves over the greenhouse frame. It had not occurred to me to do a rollup cover and it's a brilliant approach to the problem.

Thanks so much for mentioning this

Hey, good to know somebody liked our idea.

We've been using these half-year attached greenhouses for 20 years now. The plastic lasts about 5 - 8 years depending on how careful you are, and the wind, etc. We find the best method for securing it along the bottom is to avoid making nail holes, but instead buy plastic about 3 feet longer than your greenhouse, and bury the bottom edge in a trench, wrapped around and weighed down with sand and soil. For the east and west sides of the greenhouse, we've done a couple of different things. Simplest is an adobe wall with or without a door in it, and with the desired slope to its top. Where it is a low angle we simply weigh the plastic down with sandbags. Where it is a higher angle, or where we use a plastic east or west wall, we nail it to the frame with battens, but it does tend to rip along the nail holes in our annual high winds of spring.

The plastic is some kind of commercial UV-resistant tough film, specially made for greenhouses I think. It lasts 5 - 8 years, and then it's still a very useful tarp for all sorts of purposes.