Backyard Aquaponics
A place to discuss aquaponics

I'm living in Charente (France) near La Rochefoucauld (150 Km north-east of Bordeaux).

I've started building an aquaponic system by mid August 2015; I made it from 2 IBC tanks.

End of September I've introduced 18 trouts in my 750 liters fish tank. Everything seems to be allright so far except the nitrate which has been above 50 ppm since 1 week (nitrite = 0).

I'm interested in any advices/informations people who are raising trouts, may have since my experience is very small in this area. Also there is not much technical informations on the topic in France.

Welcome to the forum Yves 16 .

Sounds like it's working pretty well. If you want to deal with the nitrates, partial water changes or more plants would be a couple of ways to go.

Cheers

Might want to post some pictures to a system thread

My system is as follows:

750 l fish tank
300 l sump tank
2,5 m² for the 2 growing beds / 700 l of expanded clay balls, one siphon bell in each
All together, my system is filled with 1250 l of rain water.

I have no mechanical filter, I clean the fish tank by hand once a day with a siphon ; I put 20 to 40 l of rain water each day.

air pump 840 l/H , one pump 4500 l/H (but running at 2000l/h)

I have planted cabbages, salad, chives, lamb's lettuce… Only the cabbages are doing well. I recently put watercress in the sump tank.

You have to know that, this morning, temperature was -2°C (28°F) and, in 4 weeks, we will enter the winter season (temperature might go down as low at -15°C (5°F) for 8/ 10 days). What plant(s) would you suggest ?

I won't say everything is fine, my nitrate rate is too high (80) and I wonder what will happen in one month time.

As for my system's pictures, I have to give a look to your instructions; we will see that latter

Well adding plants is unlikely this time of year with those temps so you'll probably need to do more water changes if that's possible. For what it's worth I've had my system go through short temperature spells as low as -14 F (-25.5 C). How are you planning to heat the water? What type of fish and how many of them are you growing. Some types of fish don't eat much when it's cold and would produce less ammonia which would lessen the nitrate buildup. You also have the option of reducing feed even if the fish are eating. Nitrate isn't very toxic to fish when compared to ammonia and nitrite and while it's not great to have the high levels the fish can survive much higher levels than what you have.

I've 18 rainbow trouts.

I have a cistern underground (accumulating rain water), I intend to place a heat-exchanger between it and the fish tank. Unfortunatly the cistern has a leak...so the water level will depend on how much rain we will get

I'll see what happened in due time.

I still is unable to joint pictures, there is something I don't understand.

Picture posting issue probably has to do with sizing restrictions for the forum. This is a tutorial that one of the other members made to help explain posting pictures - http://www.backyardaquaponics.com/forum/viewtopic.php?f=4&t=21754

Hope this helps

Depending on rain water and having a cistern with a leak will also make it tough to do water changes Hopefully it will rain enough you can flush out some of the nitrates.

Bonjour Yves
I'm living in Switzerland, and i would like to know your experience with trouts with your clima-conditions. My conditions are nearly the same as yours. But i am not sure what kind of fish i will choice for my system, that would be nearly look like yours.

Regards
Daniel

Thank you Scotty,

I hope I've succeed to upload pictures, this post is a test.

You have to know, that the fish tank is inside a barn and the growbed outside under a "light" greenhouse.

I probably will build a better&bigger one, next year ( based on polycarbonate sheets 16 mm thick).

Yves,

The pics came through

If the barn is quite a bit warmer than outdoors, you may want to consider building a Recirculating Aquaculture System inside the barn for the winter. Basically you would add a couple of filters to the fish tank and disconnect and drain the plant portion of the system that is outdoors (just for the winter). The filters would do most of the same things the grow bed did but it's easier to heat the fish tank without the grow bed because the grow bed acts like a heat exchanger. When the spring comes hook the grow beds back up again. You would still need to do the water changes. Several people here use or have used RAS units including CCBear, CoachChris, RobBob and me.

You can also get through the winter using a small heater in the greenhouse or a stock tank heater in the fish tank. Lots of other possibilities as well. I just heat to keep my water above freezing but you'll get better fish growth if you aim for the optimum temp for your fish - just costs much more to do this, which is why I don't.

Cheers

With the RAS, I wonder about the nitrate rate coming up quickly.

I've read that trout do not sustained high nitrate levels, and above 50 ppm fishes may have problem.
And my system's water is closed to 80!

And what about the growbeds, what happened to the plants...

Do I need 2 pumps in such case (one inside, one outside)?

If you think you'll be able to keep the greenhouse warm enough for the plants through the winter then let it run as is. Another consideration is your day length - many plants need 10 hours of light or more, to grow. I suggested the RAS is an alternative to lower heating costs if your climate is too cold or conditions are not good for plant growth. I was trying to get across the idea that you can do 3 seasons as AP and one season as RAS (with the grow beds and pipes drained for the winter).

A RAS system has no plants and doesn't deal well with Nitrates and Phosphates so if you run this way, you will have to do some water changes. You would also need to watch the hardness and alkalinity and adjust this or the fish could potentially die. Once you reconnect to the grow beds in the spring and start growing plants again the nitrates and phosphates would be used by the plants. If they don't start going down, then you need to get more grow beds and have more plants.

Nitrates do have an affect on rainbow trout juveniles, according to at least one paper I've seen http://www.sciencedirect.com/science/article/pii/S0144860914000041. Do water changes to keep the levels lower (40 or below would be a good target but they survive the higher levels as you have seen).

Having a second pump as backup is a good idea but if you aren't going to run the grow bed over winter then only one is needed. If there is some part of the outdoor system that can't be drained then you might be better off keeping the water moving so that it doesn't freeze as easily.

Thanks a lot for all these informations I still have to digest.

I'll come back later on the matter.