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sonelin

A Question about a greenhouse for zone 6.

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I am new to Aquaponics but have done a little with hydroponics. I have grown some food indoors using an ebb and flow setup and a light. I want to build a small outdoor setup that I can use year round. I live in North West Missouri or zone 6 -23 to -18c or -10 to 0 F. So I will need to build a greenhouse to protect the water from freezing during winter months.

I just moved to a new house that I am working on rehabbing and would like to build a Lean-to greenhouse / system out back. The spot I have selected is 8’ x 14’ I am looking at attaching a greenhouse on the south side of my 1905 carriage house.

My first question is would you recommend that I build a pit style greenhouse by digging down 4’ to 6’ building retaining walls before making the lean-to? This would kind of help the thermal mass retain heat during the winter and keep it a little colder during the summer. It would also allow me to get a little more head room on the south side of it.

The second question is on tank placement. Would you recommend putting the fish tank in the greenhouse or in the unheated dark garage (with a water heater in tank)? My thought is if I put it in the greenhouse the water will pick up some of the heat during the day and keep the fish happy and healthy in the winter months. During the summer I will need to keep windows open / fan to vent the heat. I also have read that I need to keep the water out of the light so that algae does not grow fast.

Thanks,

Brad

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Hi Brad,

Welcome to APHQ.

You'll find your hydroponic experience will stand you in good stead as you expand into aquaponics.

Given your freezing winters, you'd be better off setting up a basic recirculating aquaculture system and hook up growing systems during the warmer months........since you're not going to be able to grow much in the way of plants in the dead of winter anyway.

My first question is would you recommend that I build a pit style greenhouse by digging down 4’ to 6’ building retaining walls before making the lean-to? This would kind of help the thermal mass retain heat during the winter and keep it a little colder during the summer. It would also allow me to get a little more head room on the south side of it.

Having said that, a lean-to greenhouse will be a big help for the fish and the plants. I like the idea of a pit lean-to greenhouse.

Google "rocket thermal heater" for an idea that might help you to keep your greenhouse a bit warmer on those nights when the mercury plummets.

The second question is on tank placement. Would you recommend putting the fish tank in the greenhouse or in the unheated dark garage (with a water heater in tank)? My thought is if I put it in the greenhouse the water will pick up some of the heat during the day and keep the fish happy and healthy in the winter months. During the summer I will need to keep windows open / fan to vent the heat. I also have read that I need to keep the water out of the light so that algae does not grow fast.

Either strategy will be helpful in controlling the temperature of the water in your system. Is the garage close to where you plan to set up the greenhouse?

Gary

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Hi Gary Thanks for the comment.

Thanks for the heads up about the Rocket Thermal Heater I was planning on putting in an electric or gas heater but I think I may build one of these as a primary heater with perhaps a small electric backup system.

I want to attach the greenhouse to the garage and the greenhou

se is about 30’ + from my house so it is all close. The summer shade and winter shade from the sun does not touch the greenhouse area though so it should get good light.

I have started the process of looking for a 300 gallon ish intermediate build container tank like so http://cgi.ebay.com/270-Gal-Water-tank-oil-Farm-Bio-IBC-scratch-N-dent_W0QQitemZ140463911888QQcategoryZ56996QQcmdZViewItemQQ_trksidZp3286.m7QQ_trkparmsZalgo%3DLVI%26itu%3DUCI%26otn%3D3%26po%3DLVI%26ps%3D63%26clkid%3D5275780955235737093 With any luck I can find one near my house I can buy. The ones I have so far found on ebay are local pickup only.

Thanks,

Brad

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Hello Brad,

I believe you are actually in either zone 5a or 5b if you are in NW Missouri (I'm in the KC area myself, so we're almost neighbors). Zone 6 is pretty much just the southern parts of Missouri (with the exception of some of the Kansas City area... which isn't an entirely correct label in my opinion).

You can successfully grow veggies year round with the use of a well built earth sheltered greenhouse. In the winter months, you will obviously be limited to the more cold hardy, less sun loving stuff, but it's quite possible to do in our area. You will likely need some supplemental heating during the coldest winter nights, so keep that in mind. I definitely wouldn't operate without a reliable source of backup heat. However, it will require SUBSTANTIALLY less heating than a traditional above ground greenhouse. Basically, with an earth sheltered design, you have dirt mounded up on 3 of the 4 sides of the structure. Only the south facing side is exposed and has glazing. It is easiest to build such a structure on a south facing slope (if possible), since you can dig into the slope rather than have to mound up massive amounts of earth.

Your fish tanks should be on the north wall. The ambient light should be plenty for them. It's best if the tanks are made of a dark (black) material or painted black. They will act as thermal storage by absorbing some of the sun's heat during the day and slowly releasing it during the night. It is also wise to dig a 6-8 foot deep pit about 3-4 feet wide along the entire south side (inside) of the structure (next to the glazed wall). This acts as a cold sink, allowing cool air to settle in it rather than around your plants. The glazing wall should be only slightly slanted if you want to capture as much sun light (and heat) as possible during the winter months when the sun is low in the sky. There are calculators online that will help you get an idea of the ideal degree of slant for a south facing greenhouse wall for your area (search google for that). However, I would probably adjust up just a little because the calculators are really intended to give you the best overall slant or best slant for summer growth, which is different than the best slant for winter heat and growth. If you make use of a double slanted design, you'll get the benefits of both, though it will be slightly less efficient than a purpose built greenhouse for winter use only or summer use only.

There is a good book covering the subject of earth sheltered greenhouses (aka pit greenhouses) available. It is aptly named "The Earth Sheltered Solar Greenhous Book - How to build an energy free year-round greenhouse. It is by Mike Oehler. I think it runs about $15-20. I'm actually looking at my copy at this very moment. It's not a very technical book, but is written in more of a "hey this worked well and this didn't" kind of way. Mike is not a fan of fish in the greenhouse, but I believe that has a lot to do with his lack of experience with and exposure to aquaponics.

Another idea would be to recycle some of the heat from your gray water in your house. Routing gray water from showers, washing machines and sinks to a large manifold in your greenhouse prior to dumping back into your sewer line will reclaim a surprising amount of heat. However, this can be a pretty expensive proposition depending on your house's plumbing and your greenhouse's location relative to the house. A lot of safety precautions need to be taken as well. Building code is yet another issue to deal with, or I guess try to evade if you are a risk taker. Another source of wasted heat is your laundry dryer vent. Route this to the greenhouse and only dry clothes at night, and you'll reclaim a surprising amount of heat as well. I've even heard of people routing their propane or natural gas stacks from their furnaces and water heaters into their greenhouse. This provides heat and CO2, which is good for the plants. Precautions obviously need to be taken here too. I would definitely install a CO2 monitor in the greenhouse if I did this.... just to ensure my own safety.

Edited by kellenw (see edit history)

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Hello Brad.

Ive been researching a lot int he last year and found http://www.builditsolar.com/ very helpful when it comes to green houses and a variety of other topics like solar and wind power, solar heating, etc.

This page contains a good few design ideas for sunrooms/sun spaces which I believe is what you are looking for.

http://www.builditsolar.com/Projects/Sunspace/sunspaces.htm

bellaponica

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