How to prevent evaporation

[Jeremiah Robinson]

I've been growing using aquaponics in the cold for a little over a year now, and it seems to me that one of the biggest energy suckers is evaporation from my grow beds.  I know that when water evaporates it absorbs a lot of energy, and especially in flood-drain beds the filling-expelling action can cause a lot of evaporation.

I wonder if anyone has ideas for how to best prevent water from evaporating from your grow beds?

Are DWC beds better for this issue?

[Jim Fisk]

I'll start with an easy Q. Yes we certainly do grow year round. Thankfully we grew "cold weather crops" this Winter such as Kale, Sw Chard, Lettuce, Brocs, Cabbage, herbs, etc. They all froze solid on those 2 occasions but were fine when thawed. Obviously the tomatoes and beans we grew the first Winter would have been a total loss. Keep in mind that the Kale and Sw. Chard are now 2 years old and still producing meal after meal. When you are not growing for market things get much more efficient.

Also keep in mind that was the air temp (16F) but the water in the system never dropped below 48F and that I believe is what saved everything. We even lost our 3 yr old (prob a 5 total yr old at least) plumb tree did not survive those 20F BELOW temps much to our

Jack Dunbar said:

Hi Jim. Do you grow year round? What kind of crops do you grow?

[Jim Fisk]

I have 4 black pvc 55g drums sucking up heat during the day and warming the air at niight. I also now have 100' of 3/4" pvc pipe mounted on 16' x 16" metal roofing, painted black and controlled by a T-stat and circulated by a small pump out and back to the below grade 275g IBC sump. On a Sunny day it will bring the system temp up 4F while the media beds bring it up another 2F. I also built a hoop tunnel over the 5 IBC GBs out of FREE heavy duty bubble wrap that the local furniture stores throw into their dumpsters. With management permission I raid their dumpster typically Sunday or Monday after their Sat. deliveries. I have posted pics before but I can't find one at the moment. I use 10' lengths of 1/2" CPVC for the hoops. This keeps evaporation down considerably. ALSO my FTs are full IBCs with just an access lid and no after thought cover that will leak vapor. Zero cost for lid and very effective. Fish harvest is easy by simply opening the built in ball valve and draining down to about a foot of water and then netting the big ones.

I assume you meant "DE-humidifier". Just more electric. Run a fan in the GH to circ the air. Seems to help a lot. More effective on far less juice. A real heat pump can help but again power consumption. The GB hoop tunnel had the most bang for the buck by far, however. I am thinking of starting a blog on "AP Freebies" as I am very good at finding free or next to free items that can make a big difference and I know I am not alone. Could be a big help for folks like us who are trying to feed their families and not just for pleasure. I am also considering a blog for folks who are in the "feed the family (or 2) size systems" as opposed to commercial on the one hand and herb size or smaller say kitchen systems on the other. We fit right in the middle and take our survival systems very seriously.

Jeremiah Robinson said:

Jim,

I'm so jealous of your greenhouse!  It looks awesome!  Do you do anything special for thermal mass?  If you're interested in writing a guest blog post for me I'd be thrilled.

I'd love to make mine into one like that but I built my "temporary" hoop house too close to the lot line and making it permanent would take me from zoning "grey area" to zoning "clear violation."

For those like me with a crappy hoop house, using a pool cover folded over itself or making a cover out of bubble wrap can help.  That's my plan for the next winter.  

I hear the strategy of making a better greenhouse so that less water condenses (which will keep humidity up inside the greenhouse and drive less evaporation).  

I'll definitely pursue that, but I also wonder if there isn't more you can do to the system itself to keep water in the beds and tanks, and prevent it from evaporating into the greenhouse (or living room, in Jack's case) air to begin with (even if the greenhouse air is dry)?

Would running a humidifier in the greenhouse help?  It would cool the air, but might prevent some evaporation.

[Jim Fisk]

Funny story. Our neighbor bought out the trailer home next door to them so they can control who rents it (for good reasons I won't go into now but the former owner is in jail for a drunken shoot em up rage at Th. Giv.) only to discover not one but two secret pot growing rooms. Well I purchased all the lights and GBs, pumps and about 25 iron fence posts, etc, etc. all for 100.00 and I plan on lighting the GB tunnels next Winter. So right on. The heat will not go to waste either.

Jeff S said:

OK I'm no evaporation expert but I have a large 30'x60' indoor pool and hot tub. I struggled for years trying to stop the rainfall from the ceiling. As it's been said already it takes more insulation and that solved the rain problem. However, That doesn't stop the evaporation. When you have warm water you'll have evaporation but the warmer the surrounding air the more moisture it will hold and you won't get a much visible sweating except from cold surfaces. The only way I know to slow down evaporation is to cover your tanks. I covered mine with some scrap Lexan that I had. When I remove a one foot section for feeding I shake the water drops off so I can see I'm eliminating a lot of loss. Next winter I plan to box in my GB  with the grow light inside and vent as needed. That will add heat to the water and then I can lower the temp in the GH. I'll also thoroughly insulate the FT and GB. I also plan to try some solar heating.

[Jim Fisk]

Yup, all the hot water you could ever use and it feels like it is a freebie. I started heating the HW this way as far back as '76. Man can I tell some funny stories as I experimented with the size, length and location in the woodstove of the copper coils. Damn near blew up my inlaws 1760 farm house. NEVER underestimate the power of steam. I have on numerous occasions and somehow lived to tell about it. Shouldn't have. God must still have a need for me or something.

YES, the S side of the house GH is the best of all GH worlds. For some reason I cannot explain I have NEVER been lucky enough to have that S side anywhere but the front of the house where ever we have lived including our final house here and so have never been able to do that. Our GH can be at 105F while our house is at 55F and no way to transfer that heat 250 feet between the two. Lucky you

Ck out the vid at my page here for the build on my GH gasifier woodstove. My latest design is under way for the house and I will document that and add it to my set of woodstove plans by Fall (I hope).

Jack Dunbar said:

Hey Jim, I'm envious of your GH. A thought that I had was; I built my split level ranch back in the late 80s and what I did was 2x6 construction and 1/2 foil faced foam on all exterior walls and I taped all seams. I can't remember what I used in the attic other than it was overkill. My house is very well insulated. I then got a woodstove that will take a 22" log, erected an outside chimney and burn wood. A couple of years later I built a hot water coil for the outside of my woodstove. the coil contains 60' of copper. using a circulator and a 40 gal tank, it circulates 24/7. From that tank it goes to my regular hot water heater. I have to run my electric hot water during the summer months and then when cold gets here and my woodstove is up and running, I can shut my electric off. I can produce approx. between 80-100 gal hot water a day. My woodstove and chimney are on a south facing wall so I thought of putting a greenhouse on that side of my house using triple glaze lexan etc approx. dim. of 20'( the width of my house there is 22') and maybe go out another 15-20'.Then I was going to put auto vents with sensors that would open when needed and heat from my woodstove could heat my GH and if the GH got to warm, have it heat my house Part of my chimney would also be within the GH. I go through less than 5 cord now and I do have a wood lot 5 miles away that has plenty of wood if I need it. I buy my wood 'cause I get it for 180/cord cut/split/delivered. I feel like I have a plan. Anybody got any suggestions? I love this site. You guys give me so many ideas and I love to experiment. My wife told me tonight NO chickens. I tried telling her that they will eat woodticks. I have them bad this year.   

[Jeremiah Robinson]

Hey Jim,

The more I hear about your system the more interested I get.  I love the bubble wrap low tunnels and DIY solar water heater.  

My senior project in school was a solar water heater and we got it to boil water just from the sun.  It's interesting to hear that you were able to size yours for a temperature increase that wouldn't bother your fish.  That was my worry.  I don't have a sump tank so the fish would see every degree.  

Also share your sentiments about freebies.  I'd be happy to contribute if you started a site like that.  I spent a good amount of time visiting auctions, barn sales, and craigslist when I was building my system.  Not free but pretty darn close.

Even if you don't want to write a post about it, would you mind if I summarized what you've told me about your system with the pictures you have online and show it on my blog as sort-of an educational tool?  I could put links up to Smoky Mountain Aquaponics if you'd like.

Per your question about the humidifier, that's actually what I meant.  If you keep the humidity high enough in the space you won't get evaporation at all.  You'd be sucking energy out of the air in the greenhouse, but if you're keeping more heat in your plants and your water, I think that might be better.  Probably they stop working at 32 though.

[Jeff S]

 You can counteract the evaporation of your tanks with a humidifier but if the goal is to cut water usage then the humidifier would be counterproductive not to mention the additional electric cost. It wouldn't be easy to regulate either. The idea is that you would put more moisture in the air and the added pressure would cut down evaporation. I would cover the tanks as best I could and just add water as needed.

[Jim Fisk]

Yup, I agree with Jeff not to mention I am not sure you want to add any more moisture to the situation. Just cover and control and that will save a bundle on heat as well.

Jeremiah, by all means feel free to share my pics, etc.. We are here to help folks get independent of big agri, pharma, gov, ETC. Independents is a virtue in our book and should be shouted from the mountain tops. I will, as soon as time allows, start a blog as well and share everything we have learned good or bad. I have stolen the time to make some great advances in our system of late (in the "fish room") and I will get on the camera and get some pics posted asap. I now have a swirl solids filter on the main line to the GBs and now a swirl/bio-filter combo on each Trout finishing tank (2 x 330G) and the water looks amazing without having to up the system flow. Next I will finish up the raft bed and get that online as well.

The weather here has finally turned Summer and all is magical once more here in the mountains. We had a Trout birthday dinner with the family last night and AP came thru again with an amazing meal for 6. Thought it was my 68th but I counted wrong at some point and believed my own lie. Turns out I am only 67 Bonus!!

Jeremiah Robinson said:

Hey Jim,

The more I hear about your system the more interested I get.  I love the bubble wrap low tunnels and DIY solar water heater.  

My senior project in school was a solar water heater and we got it to boil water just from the sun.  It's interesting to hear that you were able to size yours for a temperature increase that wouldn't bother your fish.  That was my worry.  I don't have a sump tank so the fish would see every degree.  

Also share your sentiments about freebies.  I'd be happy to contribute if you started a site like that.  I spent a good amount of time visiting auctions, barn sales, and craigslist when I was building my system.  Not free but pretty darn close.

Even if you don't want to write a post about it, would you mind if I summarized what you've told me about your system with the pictures you have online and show it on my blog as sort-of an educational tool?  I could put links up to Smoky Mountain Aquaponics if you'd like.

Per your question about the humidifier, that's actually what I meant.  If you keep the humidity high enough in the space you won't get evaporation at all.  You'd be sucking energy out of the air in the greenhouse, but if you're keeping more heat in your plants and your water, I think that might be better.  Probably they stop working at 32 though.

[Jeff S]

Happy Birthday Jim!

Jim Fisk said:

Yup, I agree with Jeff not to mention I am not sure you want to add any more moisture to the situation. Just cover and control and that will save a bundle on heat as well.

Jeremiah, by all means feel free to share my pics, etc.. We are here to help folks get independent of big agri, pharma, gov, ETC. Independents is a virtue in our book and should be shouted from the mountain tops. I will, as soon as time allows, start a blog as well and share everything we have learned good or bad. I have stolen the time to make some great advances in our system of late (in the "fish room") and I will get on the camera and get some pics posted asap. I now have a swirl solids filter on the main line to the GBs and now a swirl/bio-filter combo on each Trout finishing tank (2 x 330G) and the water looks amazing without having to up the system flow. Next I will finish up the raft bed and get that online as well.

The weather here has finally turned Summer and all is magical once more here in the mountains. We had a Trout birthday dinner with the family last night and AP came thru again with an amazing meal for 6. Thought it was my 68th but I counted wrong at some point and believed my own lie. Turns out I am only 67 Bonus!!

Jeremiah Robinson said:

Hey Jim,

The more I hear about your system the more interested I get.  I love the bubble wrap low tunnels and DIY solar water heater.  

My senior project in school was a solar water heater and we got it to boil water just from the sun.  It's interesting to hear that you were able to size yours for a temperature increase that wouldn't bother your fish.  That was my worry.  I don't have a sump tank so the fish would see every degree.  

Also share your sentiments about freebies.  I'd be happy to contribute if you started a site like that.  I spent a good amount of time visiting auctions, barn sales, and craigslist when I was building my system.  Not free but pretty darn close.

Even if you don't want to write a post about it, would you mind if I summarized what you've told me about your system with the pictures you have online and show it on my blog as sort-of an educational tool?  I could put links up to Smoky Mountain Aquaponics if you'd like.

Per your question about the humidifier, that's actually what I meant.  If you keep the humidity high enough in the space you won't get evaporation at all.  You'd be sucking energy out of the air in the greenhouse, but if you're keeping more heat in your plants and your water, I think that might be better.  Probably they stop working at 32 though.

[Jim Fisk]

Thanks Jeff!

Jeff S said:

Happy Birthday Jim!

[Jim Fisk]

Man oh man it took me awhile to find a pic of this. Here is my free very heavy duty bubblewrap tunnel. The furniture stores throw this stuff in the dumpster. Some are 10' long and wide enough to span the 10' cpvc hoops. I cut open the "envelope" and tape sections together to cover the 20' row. Then I trace the end hoop on a scrap or damaged piece and cut that out and tape it to the ends. I can't recommend this method ENOUGH. Keep them out of the Sun for the Summer and I bet they will last for years. Really protected the GBs and allowed for much reduced woodstove reliance in not too severe conditions like in the 20's. After this pic I added a ridge that improved the "neatness" quite a bit:

[Jeremiah Robinson]

Thanks Jim,

I'll put something together to send out this week.  Totally agree about getting independent of big ___.  Small is beautiful!

If you do get blogs / websites  going, we should exchange links.  That's the best way to get google to move you up the list.

[Jack Dunbar]

I think I'm late but anyway "Happy Birthday Jim". Man,  I hope I look that good at 67. It must be the good living... Take care.