New to Aquaponics- Senior Project

[Sam]

Hi, I am currently working on an aquaponics project that I am doing as a senior project for school.  We have to do a research paper and then make a product on the topic of our choice.  I chose to do an aquaponics system after my dad had seen one in Florida.  I had never even heard of them before but I have done a lot of research and watch countless youtube videos before constructing my own with the supplies that I could get.  Since I only had so much time to get my research done and start gathering my materials in order to start my cycle and get plants to start growing, I wasn't at the time as knowledgeable as at-least I "think" I have gotten.

I was able to acquire two ibc totes in which I used to make two systems using the tops as grow beds and I planned on latter adding on more grow beds.  I use an aqueon 449 gph water pump for each system.  It probably would have been a lot cheaper to just use one pump and and one fish tank but to late now.

My biggest questions now is my about my water quality.  I stocked 40 tilapia between the two tanks 10 days ago.  I would have liked to wait untill my system was completely cycled but because of the convenience of getting some free fish and other wise would have to wait another month until I could try and get some.  So I decided to get them even though my tanks had just started showing levels of nitrates.  Its been 8 days now and none have died but my nitrites have spiked greatly and my nitrates have only come up with about half of the nitrites.  My ammonia levels went down, but had come back up again into the 2.0 ppms or maybe a little higher.  I did a water change and my nitrites have been off the charts still.  My fish seem to be alright, but I am no fish expert ( I also put in a 170 gallon aerator between the two tanks for safety).  I had two patato plants I had started growing off of a spud and they both tipped over but I do know that potatoes aren't the best aquaonics plants.  The other actual concern is that some of my other smaller plants seemed to be tipped over on their sides while others are doing great.  A couple plants seem to have a little yellow on the leaves, but I don't see a lot of reason to add any iron chelate this early (maybe I'm wrong).  Some of my bean plants have stopped growing when they got to the surface while others seem just fine as they have gotten over 9 in. tall. (shown below)

We have to get mentors for the related projects and because I live in South Dakota I wasn't able to find anybody who does aquaponics, so I have just used some one with hydroponics for my mentor.  It is obviously an indoor system because i live in South Dakota and it is always freezing.

Please let me know of any helpful info you might have for me.

Thanks

[Benjamin Wasserstein]

Sam,

How long have you been cycling for and what temp. is your water at? All that you've described seems pretty normal for a system that just began cycling. It's good that you have nitrite and nitrate readings, and not just solely ammonia. This means you have Nitrospira and Nitrosomonas bacteria in your system. Without a more detailed nitrite reading, an idea of how big your fish are, and without knowing your tank/grow bed size I can't really make any sound recommendations. Regardless, tilapia are hardy fish and as long as you don't kill off your bacteria your nitrate levels should keep building. Make sure you let your water sit for 24 hrs to dechlorinate when you do your water changes to avoid killing off any bacteria. Keep in mind that optimal temps for nitrifying bacteria are between 77-86'F, and at 64'F their growth rates drop by 50%.

 

I started cycling my system and added fish 3 weeks in with no signs of nitrite/nitrate and a reading of .5 ppm ammonia. Within a few days I had nitrite/nitrate and I monitor water chems much less now. I didn't even bother with any water changes after adding fish. The yellowing leaves is typical for a system that's just reaching it's equilibrium. To be honest though, 40 tilapia may be too much into the future as they grow bigger if you're using a 1:1 fish tank to growbed ratio (based off the picture of your two grow beds). What's the size of your grow bed/ fish tank? If you're really concerned, take detailed nitrite readings and do some research into the chronic toxicity of nitrite to tilapia. I think your system just needs some time, but here's a good paper in regards to nitrite toxicity to fish that was published in AFS Transactions....

 

http://ciresweb.colorado.edu/limnology/pubs/pdfs/Pub079.pdf

 

Cheers,

 

Benjamin Wasserstein

[Rob Nash]

too many fish too soon.. keep your pH nice and high for now.. not the best for plants, but great for the bacteria.. it looks like you need more light( or drop them closer to the plants) keep a fan blowing on them to make them stronger.. with that much nitrogen, you may want to go buy some bigger plants and wash the soil off.. you need something that will use some of the nitrates.. the fish can handle quite a bit.. I used to see nitrites in the 160+ range and the fish did fine..

PS>. it looks like you went with all river rock... if so, your pH will most likely stay very high, don't try dropping it with acid, it wont last. you might need a new, inert, media... like granite.

[Sam]

Rob,
I read that by putting my rocks into some vinegar they would fizz if they effected or gave off pH and they did not. I've checking my pH levels and they have stayed about the same at 6.8. Would you recommend raising my pH higher? I have more then just the beans growing, but they are just the biggest right now. I also have a lot of cucumbers, tomatoes, beans, beats, and a lot of lettuce and leaf lettuce. I even but in some potato spuds that have started to get bigger just to help with the absorption of nutrients for now. The problem I have is that I haven't been able to find any places that actually sell any vegetables. I suppose I should be able to find a place that sells some bigger types of flowers but I'm not sure that they will actually take up that much more nutrients? Maybe there is some places that I can get plants, but I have no knowledge of any right now.

Benjamin,
Both of my fish tanks are 175 gallons of water and my grow beds are both at about 50 gallons each. I have maintained my water temperature at 75-82F and I have just gotten my timer dialed in so that it keeps the temps more steady. I can bring the temperature up, but I thought that 75-80 is a pretty fair temp. I have a 130 gallon tank that I got to use just recently for gassing of the chlorine. I have thought of maybe pulling out all of the fish and putting them in the 130 gallon tank, but I'm not sure I want to be changing the environment or move around the fish very much if I don't need to.

Thanks for the replies