Backyard Aquaponics
A place to discuss aquaponics

I plan on some radient heat mesh on the render layer of the concrete block for the days where we get some cold snaps. In the future those could be tied to solar, but I'm really thinking that the sump will be big enough deep enough that I should not have that big a change in temps. The sump will be 5x12 feet at 6 feet in the ground with water levels at about 4 feet. 1800 galloons or so. That coupled with the grow beds burried two feet down (also with radient mesh), I hope to achieve pretty stable temps year round. I guess in a way that is subterranean heating/cooling. I had thought about pumping air down under the concrete, but I think the pipes would fill up with water pretty fast. So my plan is just a lot of mass via concrete and water.

My bigest concern is floating the whole greenhouse up during wet wether as our water table here is pretty high - and since it will basically be a half empty swimming pool, I need to figure out if I will need external drainage around it. That would meen another sump and piping out to the street.

Anyway - subterranean heat....ya sort of, but just with water circulation instead of air.

Mark

Just a reminder,
Though the water and the gravel in the grow beds are great thermal mass and sinking stuff into the ground will have some effect......

If you are running flood and drain in the grow beds while the air temp is at some extreme in the greenhouse, the gravel does a really good job of heat exchanger between the air temp and the water temp. In essence if the air in the greenhouse gets really cold, the act of flooding and draining the grow beds essentially chills the water.

If you don't want that to happen, you either need some way to keep the air warm enough over night in the greenhouse not to chill the water too far or you might choose to run the beds constant flood overnight on the extra cold nights. The other option might be to shut down overnight but that means the gravel will get well chilled and when you start up again in the morning the gravel will still chill the water a bit unless you wait till things warm backup. It might depend on the fish load and how much circulation you need to keep going overnight even on cold nights (depends on fish type too.) Also some plants are fine with constant flood more than others so perhaps just leave certain beds constantly flooded and shut the others off for the night? Just some options I've toyed with in my system.

Now that is funny!

Have to rethink things, HOA did not approve greenhouse.

Dang bro. Sorry to hear that. Though it's not as much a setback as being denied a greenhouse in, say, New Hampshire or Buffalo would be.
So. are you going to try pretty much the same volume (tank, sump, deep deep GBs) as you were before, or do you have to modify and re-submit just to have concrete in ground? I wasn't sure how much of it was subject to the HOA's blessing.

For my own setup, I never have locked myself into a greenhouse structure design, in my microclimate i just wouldn't need it for heat very often. Shade is another matter. Still playing with tentative shade ideas but it changes as my GB / pump / drain plan evolves.

Best case, you are getting freed from a rectangle and your system can stretch out more...

Rick

Ok - done crying now and started to think about what to do instead. If I move it further behind the house, I have less of a problem with the burried power line and actually end up with a little more room to work with. I can proabably squeeze out a 12x30 area to play with. That area would not be visible from the street and the regulations are a little more relaxed for that. I will have to redesign the entire system though as the wife would like the entrance on the 12 foot side as apposed to the long wall in the last design. Oh well, like everyone says, the design is half the fun.

Back to the drawing board!
Mark

And the design generally keeps on changing right through the whole building process... 12 x 30 is still quite a nice area to play with..

I know a guy that was able to put in a greenhouse even when the HOA wouldn't allow it. In his state, it's against the law to restrict the installation of a renewable energy system, so he designed his GH to have solar collectors in the ceiling. They are able to rotate and let some sun in. It's quite clever!

Ya - nice idea. If I was going to invest in solar, I would be an idiot not to put them on my south facing roof that has no shade. It is also not your standard sloping roof - it is a very shallow slope and picks up the most sun all year of any other surrface on the property. The rest of the yard gets a fair amount of shade. The other thing I could do is forget the greenhouse, but I like the idea for keeping water temps up and running tilapia. And keeping the critters out that are forever digging up the dirt garden.

Peas are comming on in the dirt garden and to my supprise it was not the outside critters getting them this time...I never knew dogs like peas.

Mark

Actually a flat slope isn't ideal for solar. I happen to know this because I installed a 3kW system on my roof 3 years ago. Turns out my roof was ALMOST ideal - south facing, about a 25 degree slope. The solar system inspector for the city said a 30 degree slope is ideal in this latitude. Austin has a really good solar rebate program - I don't know about Houston. With the fed tax rebate, it paid for more than half our system. So I don't feel bad in the slightest about the 75 watts my pumps are drawing day and night, cause I produce far more than that.

I got a quote for the concrete work today - $5400 for the whole thing to be pored concrete....3200 if it is just the horizontal slabs and I do the rest with concrete block myself......will have to work through the numbers of doing it myself. The quote came in 1k over my max.

Even when I had my system in my "greenhouse" (granted my greenhouse was little more than just a cold frame with plastic film) I couldn't keep the water warm enough to simply keep tilapia alive without supplemental heating, let alone growing. If you are going a better design of greenhouse (say double glazing or double layer) you can probably keep them alive without supplemental heating but to keep the water temp up to growing temperatures over winter will probably still require extra heating. I found that trying to recover heat during the day in winter by leaving the greenhouse closed up meant it got hot in there during the day but was still quite chilly at night and I think my plant production suffered because of it. I'm quite partial to many of the cool weather crops that really only grow well here during the coolest part of the year. If I cover my system with a greenhouse, those plants don't grow nearly so well in the system. (This left me with a dilemma, during winter I was trying to recover heat for the tilapia which meant that both cool weather crops and warm weather crops were struggling in my system over winter. The of course since I'm in a sub tropical climate there is a part of summer when few crops thrive, by having a greenhouse that I felt I needed to keep closed up to keep the tilapia warm in winter, I was really hurting my ability to grow many veggies through the year.)

I have also found that having a greenhouse doesn't guarantee that pests stay out (though it might delay when they get to your plants for a while), it just means that once they get in, there is often more of a challenge dealing with them.

I would still kinda like to have a greenhouse so it would be easier to keep a selection of tropical plants alive through winter, but I don't want it for the sake of tilapia.

Yes - I may find that I cannot keep tilapia. With the sump 20x4x4 buried 6 feet deep, I may find water temp may stay to cool even in summer. Will have to determine species once it is built and I can get a better idea of temps. I'm gonna keep my fingers crossed though.

I was just reading the super profits tax thread...the luagage is getting a little harsh there...very off putting!

C'mon DJV, Whats happening with your system. Updates please.