Backyard Aquaponics
A place to discuss aquaponics

What a bummer about that company not providing an accurate dimensions for the Poly tunnel. Perhaps you need to drop a name. Yes you're turned that issue around and built yourself one of the finest looking systems I've seen here. The Poly Tunnel looks very well made too and it really changed the look of the place. Good job getting it installed alone and in the wind even. You possess great determination to go along with your intelligent planning.

Nice work Jens! Super tidy system, nice solution and fits really well into your poly tunnel!!
I think I'm going for a poly tunnel next year as well, my wood framed greenhouse is getting really crowded.

What water temperatures are you expecting? The guy selling trout fingerlings in Belgium insisted that I go with something else than trout as 4 of the 6 growbeds are inside the greenhouse and the temperatures will just climb too high in summer...
I'm at 18 degrees water temperature after the hot weather (30-35 degrees C) of the last few weeks, which is getting on the high side for trout apparently. Thinking about European catfish instead of trout, even though it has less of an appeal to me than trout

Thanks Brian, you're too kind!

The polytunnel is actually a pretty cheap model. Only around 250 USD. It's a Chinese manufacture peddled by a local Danish company. They also have better quality tunnels, which are around 3 - 4 times the price. So I opted for the cheap version to test the whole polytunnel idea. I can always install a better one later if I want.
The frame is not very sturdy as the pipes are a very thin gauge 1" diameter.
For the price I did not expect more, but I was pretty bummed over the measurements not being accurate. They are more than 5" shorter than advertized - and I even called their "x-pert" hotline to check.
That's why the whole tunnel is a bit warped. One side is actually longer than the other in order to fit around the 6 tanks.

I must admit I'm happy enough with the end result none-the-less.
Today I emptied the old greenhouse of plants and moved some of them to the new house. Tons of mint and a couple of parsley and coriander.
I also strew some seeds directly into the media beds. Coriander, parsley, basil, cucumber and tomato seeds all went in. Let's see what happens!

Now I need to poke holes in all the rafts and begin sowing in net pots to fill up the rafts. That's the tedious part in my opinion - sowing in pots. Instead of planting all of it out in one go, I think I'll pace myself and do one row per bed per week. Each bed will have one product. That way I will have produce coming along each week when harvest time comes around.

Cheers - Jens

Thanks Rudolph!

I wanted to build a system which maximizes the use of space inside the polytunnel without any need for digging. One of the aims was to get as much water as possible in the setup to be able to keep the temperature as stable as I can. It also gives me a system which is better at coping with various issues and not risk ammonia spikes etc.

I want to keep European catfish as well! They are indigenous to Danish waters (and delicious) like the trout. I will go for rainbow trout as they are the most heat tolerant. I also have crayfish (Astacus Astacus) which live all over the place here. That's kind of one of my principles. Raise local species to minimize the need for heating or cooling.
According to the hatchery I know the trout will tolerate up to 24 C water temp and down to 0.
So I see no problems over winter. This summer I will see how high the water temp gets and then probably get fingerlings in late summer. Should it get too warm come next summer the fishes will be large enough to harvest and put in the freezer.
My guess is the water will not get too warm if I only make sure I have plenty of air movement in the GH. The past few days it's been over 20 C here and clear skies, which really heats up the GH quickly.
With all the "windows" on the sides open and the door in one end open it has been perfect inside the GH. Should a really warm sunny period come along I can always cover the GH with shade cloth.

Bottom line - I think it will work out fine.

Actually - the media beds with ebb and flood cycles help cool the water contrary to what most people think. I think it was on this very website that a test was carried out showing this. As I recall, one of the important points is to make sure the top 5 cm of media does not get wet, as this is the media that gets heated by the sun. This way you also avoid any algae on the surface of the media. The evaporation from the media when the beds are empty of water will cool the media down and subsequently cool the water as it flows in.

Cheers - Jens

Very neat system Jens. Can't wait to see your plants take off. Also, that is really good to know about the media beds. I never considered evaporative cooling from them, but it does make sense...

Thanks Dominic!

Nice work Jens. I have been looking at what appears to be the same poly tunnel recently thinking I might add it next year for more space. Once we started all of our seeds in my little stick built greenhouse it got crowded fast! Plus I have more things I want to grow than I have room for right now, so I will probably do a polytunnel next spring and build a second AP system that I only run from spring until fall, then my stick built greenhouse will be my winter greenhouse to try and keep it warm year round.

This is the poly tunnel that I've had in my wish list on amazon for a while now... looks like the same one... https://www.amazon.com/gp/product/B00IY ... N20Y4Q46KG

$180 US dollars. I was considering building my own because a guy down the road from me said he built his 8ft x 8ft x 44ft for about $600, so I thought if I could do 8ft x 8ft x 22ft for $300 would be good, but if I can do 10ftx7ftx20ft for $180 even better!

As for Rainbow trout, mine I kept until about 72F (22.2C) and did not have any die due to heat, but I was getting nervous.

I think that flood/drain water temp test was done by Collum Black Byron if I recall correctly.

Hey Rob,

That polytunnel looks very similar, although it's not exactly the same. I see some minor differences in the frame and obviously the door opening is much larger.

I have also looked at all kinds of ways to construct my own tunnel, but large scale manufacturing just brings the prices down to a level where it only makes sense to build your own if you want it to last many seasons.


I think you are right about Collum down under making that test.

So, it turns out this season for the new greenhouse will be much like last year for the small setup.
I got it up and running too late in the season to really make the most of summer, but that will allow the system to settle in and me ironing out the kinks for a flying start next year!
I will definitely have to get better at germinating in my own opinion!
I just don't feel that I'm on top of that. Lots of my starts grow a little leggy. Perhaps I need to set up some artificial lights....

The tomato plants are not taking off in the new system at all. They did not appreciate the move!
I guess the new system didn't have any nutrients the first days after I moved the plants from the old setup and then I had to dig everything up when I emptied out the beds to move them.

I'll probably buy some plants one of these days just to be able to get some produce out of the GH this summer.....

Cheers - Jens

The guy down the road from me said he got 6 years out of his home built greenhouse using a 4 year plastic before it failed, and he said that he would have gone longer if he had thought sooner, he started putting felt on top of his PVC tunnel frames to keep the plastic from rubbing on the PVC. The area that failed did not have the felt for extra protection.

I'll keep an eye on how your tunnel holds up before I decide which way to go. Without seeing it in person it's hard to tell what the cover material is and how well it will last.

Definitely stay tuned and I will let you know how it works out.
The pro polytunnel companies use some kind of low friction tape on all the frame tubes that come into contact with the cover in order to minimize wear.
The cover on my tunnel is this reinforced tarp material you see all over the place. According to the company it also has UV filter properties, so the actual material is not the same as the tarps, but its made the same way. I'm also curious to see how well it holds up.

Cheers - Jens

Hi guys,

A couple of weeks ago I welcomed some 200 Trout fingerlings to my system.

I had them delivered by a very well reputed breeder who do deliveries all over our small country.
He normally delivers to put n' take lakes, so fingerlings is not what he usually has requests for.

The gentleman found my backyard project so facinating he sold me the fishes along with at least 2 months worth of ecologic feed for around 80 USD!

I now have one more supporter for my commercial scale dreams!
I have a land-owner right next door who keeps asking when we will put up some sort of operation on his land.
Just need some cash investor and some contracts to deliver to and we will get building....

Hee hee hee - dreams are free and ideas are bulletproof!




Enjoy!


Jens

Nice job Jens, what type of trout are they? They look pretty large already, so for $80 for 200 of them I think you basically stole them. I think I paid more like $60 for 25 trout when I bought mine and they were about 6 inches at the time, but I still thought that was a deal, so you really got a good deal.

I found my local trout hatchery was pretty informative and willing to share information when I bought my trout. They gave me a small tour of some of their buildings and talk through some of their processes when I was picking mine up. I will probably head that way again in the next couple of months as my water temps start dropping again (I think they told me their water temps are 52F year round, and rainbow trout can only handle about 70F so I need to wait at least until my water temp is below 70F to go get them, my greenhouse is getting to low 70F's at night now but back up to 82F during the day, haven't tested my water temp lately. I will have to pick their brains a bit more this year now that I've raised a couple dozen trout once.

I think if the neighbor wants you to help build something on his land you just need to get terms that he fronts the money to build it then you both put in the work and split the profits =) Let him pay for it but you get to make money off of it. Get it in writing first! =)

Thanks Rob,

Rainbow and Gold Trout.
The breeder let me have the fishes for around .15 USD per head.
The balance was for the feed (enough for the first two months at which point I need to go up in pellet size), and I actually gave him 15 USD extra and refused the change.
Mind you, he filled my lot into a separate tank on the truck and made an extra stop for me.
In the tank next to my fishes he had 400 trout at around 2 lb per fish!

He is extremely helpful and interested and encouraged me to call if I have any questions.

My neighbor wants some kind of joint venture where I basically rent his land to put my commercial setup on it.
We haven't talked seriously about it, but if we are doing something he will have to invest more than just the land he has laying around anyway. :-)
It will not happen very soon anyway. I'm starting in a new job on September 1st, so I have my hands full.

Cheers - Jens

Hey Jens, it's been a couple months, how did the end of summer treat you? Any progress?