5 year old Greenhouse Update

[dendronepthya]

A few years ago, I started a thread about a greenhouse aquaculture system. It's been an on and off project this entire time and I wanted to share a bit on how things have changed since the beginning. I can't seem to find the old thread so I'll start with a general overview. Construction of the greenhouse began in the middle of 2003. The greenhouse is made from polycarbonate structural sheet and an aluminum frame. The company that supplied the greenhouse kit likened the construction to building a fence. In theory, if you can build a fence, you should be able to make a greenhouse. Unfortunately, we do not have the luxury of living in a theoretical world. After having built a fence, I can safely say that a greenhouse is a LOT more difficult, and we were quick to call in the contractors to assemble the kit.

The greenhouse itself looks very different today, and I'll spend the next few posts talking about each thing.

 

[dendronepthya]

In 2007, we actually had a bit of a catastrophe. In February, there was a blizzard that caused the primary heating source to fail. At the time the entire greenhouse was heated by a big natural gas furnace. Even the tanks were heated by it. We would pump water to a set of heating coils near the output of the furnace and back. Anyhow, snow piled up on the roof of the greenhouse so high that it blocked the furnace's chimney and caused the air to back flush and blow out the pilot light.

Here is a pic of the furnace:

While it was no fun to lose everything, it did give us an opportunity to fix some of the things that we would not have been able to fix otherwise because we had 3000 gallons of reef systems in operation. We took everything out of the greenhouse in 2008 and installed a new heated floor. For the first few years we had a gravel floor seen below:

It was great for drainage, but it really allowed in a lot of cold even though it was about 6"-10" thick. We installed a 4" foam pad and poured in an additional 4" on concrete. The red tubes are the heating coils that provide the radiant heat.

The new heating system is a tankless Rennai that was 40% more efficient than the previous gas furnace:

It looks pretty complicated, but it's surprisingly easy to use. Not only did it cut our bill significantly, it also did a much better job of heating the actual greenhouse. Before we were pretty happy to get 70 degrees tank temperature in the winter, but after installing the floor we were getting 72 degrees.

Here is what one of the tank sets looks like now:

 

[dendronepthya]

This year we decided to make some more improvements on the greenhouse. Our focus this time around was directed toward heating and cooling efficiency. The first major change we made was the walls and ceilings of the greenhouse. For 5 years now, a single pane of double-walled polycarbonate has made up the greenhouse walls.

Initially heating the greenhouse was a bit of a challenge as a result of heat loss through the walls and ceiling. This year we finally committed to installing a second layer of double-walled glazing to the entire greenhouse. Adding a second layer of glazing would in essence create three air gaps for insulation, one in the outer pane, one in the inner pane, and a large gap in between the two sheets of glazing. The hope is, once the second layer of glazing goes up, the heating bill in the winter would drop significantly. A single panel of 8mm double-wall polycarbonate has an R-Value of 1.6. By adding the second panel, I suspect we would more than triple the R-Value of the wall to something in the neighborhood of 5.0. An R-Value of 5.0 is roughly equivalent to 1.5" of polystyrene foam. Installing the second layer of glazing was a lot of work but luckily we got a lot of help from friends and family. The ceiling installation was professionally done and the final product was very nice:

 

[dendronepthya]

While the first change was made to better address heating bills in the winter, the second change was done to lower the cooling bill in the summer. Frankly, the cooling bills in the summer were never that high to begin with, but the greenhouse itself on certain summer days was unbearable to work in and the temperature in the tanks approached 90 degrees. The large 48" exhaust fan did a great job of moving air at the level of the fan however heat would quickly build in the upper regions of the greenhouse and cause the building as a whole to be uncomfortably warm whenever there was direct sunlight. While we were working on installing the second layer of glazing on the ceiling of the greenhouse, we could feel the temperature increase 10 degrees every few feet. It was probably close to 150 degrees F at the top of the greenhouse.

To combat this heat issue, we decided to look into automatic vents at the top of the greenhouse. Farmtek sells a very elegant automatic vent system. When I first saw the item in the catalog, I was thinking it was an electrical device on a thermostat but in reality these units are not hooked up in any way to an electrical source. The vents are opened and closed by a black piston filled with a special fluid. When the temperature rises, the fluid in the piston expands causing the vent to open. Once the heat in the building escapes the fluid in the piston cools and the vent closes. We installed three of these vents and the impact was immediately noticeable. What was once an uncomfortably hot greenhouse in the summer became a very pleasant one.

The exhaust fans now come on half as often and almost never run full blast. In past summers, the main exhaust fan typically ran at 100% for at least five hours a day. The fan is a 10-amp unit so one can imagine the electrical draw. Now that the vents in the roof are in place, the main exhaust fan stays inactive for much of the day and practically never has to run at 100%.

 

[dendronepthya]

Lastly, we added a new set of tanks increasing the total volume of water from 3,000 to 4,000 gallons. Total volume is a bit misleading because the tanks could just be really deep, but there is a decent amount of square footage taken up for coral growth. Here are the pics:

Our water chemistry was crazy for a while so we recently installed 4 GEO calcium reactors (1 for each of the 1000g systems).

That's about it for now, I'm sure I'll think of something to add later.

 

[ctenophore]

Nice work on the improvements.

Did you consider geothermal for the radiant floor heat source? If so, why did you opt for gas?

Did/do you use any shade cloth? If so, did you use aluminet and find it to help with temperature control from infrared reflection at night?

I ask because I am about to experience my first winter with my new GH up here in the north (Maryland). Mine is built from aluminum and insulated argon glass. You can see a thread about it at R2R and wamas.org.

Justin

 

[dendronepthya]

<a href=showthread.php?s=&postid=15737200#post15737200 target=_blank>Originally posted</a> by ctenophore
Nice work on the improvements. Did you consider geothermal for the radiant floor heat source? If so, why did you opt for gas?

I did consider it. I'm still considering it actually. We went with gas out of convenience. We had a gas line already from the old furnace system, and the plumbing professionals in our area had lots of experience installing radiant floor systems.

I really like the idea of using a geothermal heat pump but I just haven't seen personally the best way to implement it. I think it would be a great system to run in conjunction with what I have now in case there is a failure of some kind again. Having a separate redundant system would be nice.

<a href=showthread.php?s=&postid=15737200#post15737200 target=_blank>Originally posted</a> by ctenophore
Did/do you use any shade cloth? If so, did you use aluminet and find it to help with temperature control from infrared reflection at night?

We use white shade cloths. Aluminet sounds very interesting. Anything to help keep the greenhouse warm in the winter is a welcome addition. It seems to be a fairly inexpensive tweak too relatively speaking.

I read your greenhouse thread. You've done a great job with it. I am surprised you are not having trouble with the light intensity you are allowing in. 1200 is a ton. I have some corals that react poorly to much less light than that which makes me wonder if my issues are water chemistry-related rather than light related.

 

[Wolverine]

Than, here's a link to a thread you started almost exactly 6 years ago. I think this is the one you were talking about.

http://reefcentral.com/forums/showthread.php?s=&threadid=246772&perpage=25&pagenumber=1

 

[ctenophore]

<a href=showthread.php?s=&postid=15737286#post15737286 target=_blank>Originally posted</a> by dendronepthya
I did consider it. I'm still considering it actually. We went with gas out of convenience. We had a gas line already from the old furnace system, and the plumbing professionals in our area had lots of experience installing radiant floor systems.

I really like the idea of using a geothermal heat pump but I just haven't seen personally the best way to implement it. I think it would be a great system to run in conjunction with what I have now in case there is a failure of some kind again. Having a separate redundant system would be nice.



We use white shade cloths. Aluminet sounds very interesting. Anything to help keep the greenhouse warm in the winter is a welcome addition. It seems to be a fairly inexpensive tweak too relatively speaking.

I read your greenhouse thread. You've done a great job with it. I am surprised you are not having trouble with the light intensity you are allowing in. 1200 is a ton. I have some corals that react poorly to much less light than that which makes me wonder if my issues are water chemistry-related rather than light related.

1200 is only along one thin strip- all of the stony corals are around 450-500. Which is still a lot. I had trouble with that much light when I was growing them in my FL greenhouse. I think water quality definitely plays a role, as my water up here in MD is much cleaner than FL.

The idea behind geothermal is that you have a closed loop well in the ground that supplies heat that you pump through the floor loop. So instead of a gas boiler before your manifold, you have the heat pump instead. It should be very easy to retrofit, (or add to in order to keep your existing gas system in place for redundancy's sake).

I only use the blue cloth. I have heard from many people that it aluminet good for cold climates since it reflects heat back down at night, so I may try it in the winter up here.

 

[garrettm85]

Very good stuff! I love what you have done with your green house! Do you have any algae issues? If so what do you use to control the algae? It looks like you have a ton of room in your greenhouse! Do you churn a profit or is this primarily a hobby greenhouse?

Excellent stuff!


Garrett

 

[hamburglar]

I would call that a "non-profit" greenhouse Thanks for sharing though. Your greenhouse project is at the level that most of us dream of. Everything looks very neat! Very very nice!

 

[nauticac4]

Looks great but I wanna see some corals growing!!! All i saw were empty tanks, when will you be back up and running?

 

[dendronepthya]

@Wolverine - Thanks. I did a search and wasn't able to find it.

@ctenopore - The Aluminet sounds very interesting. Until now I didn't realize that things in the greenhouse radiated infrared light at night and that you could actually bounce it back down as a way of heating. Perhaps later on I'll give it a try. I want to first see what a difference my second layer of glazing does to my heating bill.

@garrettm85 - Thanks for the complement. I have had different algae issues over the years, so it's not any one particular type that causes a problem. A long time ago one of the systems turned into green water to the point that it looked like pea soup and you couldn't see 2" into the water. I got a pond sized UV sterilizer and that problem went away in 48 hours.

What is more common is a hair algae outbreak every spring. There is a really big difference in light levels going from winter to summer, so once the photoperiod extends by a couple of hours and the light intensity doubles, the extra energy starts up the algae. We combat this by using more shading and cutting back on feeding a little bit during the season change.

We have a bit of an algae issue right now, but it's from an invasive red macroalgae. It sort of looks like red cotton, and digs into everything. I'm in the process of removing it by scrubbing and siphoning it into a micron filter to collect the small bits that break off. After the micron filter, the water goes through the UV sterilizer in case any small bit made it through the filter cartridge. It is a time consuming process to do this on such large tanks, but it's gotten to the point that it is necessary to really keep it under control.

@hamburglar - Thanks! We keep making improvements on it so the break even point keeps moving further and further out. What is nice though is that it is becoming so efficient that very low sales can pay the bills to keep it running. The first winter, I think our gas bill was about $1600-$2000 per month. I would be surprised if it was $400 now with all the updates. Electricity is probably $150 a month year round and a lot of that is from the lights we use for our benefit (not to grow corals).

@nauticac4 - The three original 1000-gallon systems are full of corals (the new system is empty), but I was a bit worried about the forum policy regarding showing corals. It can't look like a commercial. I'll post just a few of the things we've grown here

 

[dendronepthya]

Here are 5 pictures I took last fall. The corals look the best in the fall by far. In the summer a lot of them take on lighter colors as they expel zooxanthellae.

 

[fishnut321]

Very interesting are you able to maintain consistent temperatures through out the year with the new improvements? Have you noticed improved growth over traditional artifical sources? Lastly, is the overhead for this system running significantly lower than using typical artifical lights?

 

[dendronepthya]

@fishnut321 - Yes, the temperatures are very stable. This summer after we installed the ceiling vents and an additional circulation fan, the tank temperatures were rock solid at 77 degrees F.

In the winter last year, our tanks were consistently 70-72 degrees F. This winter, I expect better performance because of the added insulation as well as another 1000-gallon system acting as a heat sink. My hope is to maintain the tanks at 73-74 degrees. So, year round, the temperatures only fluctuate about 3 degrees.

Before all of these updates, the most drastic temperature swings were like 69 degrees in the winter and 90 degrees in the summer.

As far as lighting goes, it's tough to say. There is no question that the greenhouse takes very little to operate given the volume of water it holds. To operate a system like this in a residential building with lights, etc. I imagine the annual cost would be somewhere in the neighborhood of $20,000 per year. This greenhouse doesn't take nearly that much. The problem though is that you have to deal with seasons where some corals are unhappy about too much light or lack of light.

 

[hamburglar]

And you have to consider that a greenhouse isn't very cheap, plus panel replacement costs.

It is just a trade-off. You get free light. People using artificial lights in buildings get better insulation and less "building maintenance" costs.

As far as which is better..........your guess is as good as mine.

Great photography by the way Dendro!

 

[aqua_reef_01]

wow that is an awesome set up. If I could only afford to do that!!! But I could afford some frags lol. Send me a price list for the shown items if you would.

 

[Logzor]

That is an amazing system. Judging by those corals picture it looks like all of your hard work and dedication is paying off!

I assume this is built in athens, as your profile states. When can us cincy folks stop by?

 

[H20ENG]

Great update Dendro! I was bummed to get a bunch of reply emails about your GH thread only to find no updates.

Justin,
I finally got to check out your thread on wmas. Awesome job!