Backyard Aquaponics
A place to discuss aquaponics

Aloha Aquaponics Friends

I thought people might be interested in specific information on nutrients, nutrient levels, and system startup we learned during our last year of operation, and thought this might be an interesting and useful topic for everyone to contribute their information to.

I took the UVi (University of the Virgin Islands) Short Course a year ago. They told us how to start an AP system: "Just wait two to three months and the nitrifiers will show up all by themselves". Of course, in a commercial situation when you are paying a monthly note and $700 electrical bill that can be kind of annoying to waste so much time with no fish or plants in a system.

So we used this waiting method on our first system. We didn't know any better yet, and we still had a nitrite spike that went to 10 ppm on the test strips. I suspect it may have been higher than that, because the test strip developed its full violent pink color indicating 10 ppm four seconds after it was dipped, instead of the full 60 seconds development time. It took two and a half months for nitrites to appear in this first system because we just waited, but finally they showed up. We were lucky and didn't lose any of the 400 lbs of fish in the system, although they got grumpy and stopped eating for the two weeks or so of the spike.

Then we found Aquatic Eco's product #239211, gallon size of nitrifying bacteria for $43 plus shipping and inoculated our next two systems with that. The techs at Aquatic Eco were really helpful. The first 20-raft system we started with this inoculant bacteria had 3ppm nitrites within three days and nitrates showing up within 5 days We planted into the system five days after inoculating. This was with a full load of fish in the system, almost 800 lbs.

Problem was that the nitrites still spiked at 10 within the first five days and stayed there for two weeks before coming down. We didn't know any way at the time to deal with this; and since it is an 11,000 gallon system and we are on expensive (and chlorinated) city water we didn't have a way to economically exchange water to dilute. Fortunately, we have a bunch of toughy tilapia who just endured it all.

We inoculated the next 36-raft system with the gallon of bacteria the same way, and started to pound sand when we saw nitrites go to 10ppm within five days of startup. This time we had a brainstorm: we knew the nitrifiers are light sensitive, so we removed about half the rafts to partially uncover the troughs and removed shade covers from the tanks to let light in. Nitrites went down to 3-5 ppm from 10 overnight, stayed at 3-5 for two weeks, then went to 1 or so, at which point we covered the troughs and tanks back up. This system had 1,500 lbs of fish in it when we started it. Everything turned out fine and system water was ready for planting five days after system startup.

I've seen those graphs of the nitrite spike versus the time function and all I can say is that our nitrite spikes had similar relationships to the ammonia and nitrate levels, but it all happened much faster in a shorter time period than the graphs led us to expect. Our water varies between 72-80 degrees F depending on time of year. Temp doesn't seem to make much difference during startup as we started systems during cold periods and warm periods and noticed no definite difference.

IF I was going to put sensitive fish in my AP system instead of the seemingly bulletproof tilapia we have (my wife calls them "Our Delicious Fishes") I would start systems with NO FISH in them, using ammonium chloride at about 1-2ppm, get through the nitrite spike, then when nitrites are down to 1 ppm or so introduce the fish. Don't take chances. We had no spare tank space to put fish in, and were under the gun financially getting started (and still are) so we put everything in at once and got lucky.

Except for the startup period during which these fluctuations occur, during normal operation our systems run around 0.5 ppm nitrites, 20-80 ppm nitrates, and 0.5 ppm ammonia pretty steadily for months at a time. The fish are extremely healthy; we've never had a disease episode of any kind in thousands of fish over a year's time. I'll post another post about disappearing nutrients after awhile if anyone is interested, this has gotten long enough.

If you used light to stop the nitrifiers from converting ammonia to nitrite to stop the nitrite spike wouldn't the ammonia that can't be converted just spike and kill all your fish. The nitrite level of 10ppm must of started out as a lot of ammonia.

And bacteria you got for $43 plus shipping. Wouldn't it have been easier to just throw a couple of thousand liters of water from your other system into it.

Ditto... Duff... and IMO would have probably given exactly the same results...

Nitrites would have shown up in about 3 days... and spiked to about 10... with 800lbs of fish producing bucketfuls of ammonia....

And then taken about 2 weeks to decline and the nitrates to boom...

Exactly they cycle process, and time, you'd expect to see in a "seeded" system... whether by a bottle of "bacteria" or using water from an established system....

IMO... your fish were very lucky to have survived either the initial ammonia load of 800lbs... and more particularly the nitrite spike of 10 ...

Other than goldfish... Tilapia is probably the only thing that would...

Out of curiousity Tropic... do you recall your pH and water temperature values at the time??

And would I be right that you were providing large amounts of oxygenation....turning over your water rapidly, perhaps even doing water changes???... and removing solids from the system water???

... 22-26 degrees C.... perfect temps for cycling.... no wonder you didn't see any difference in your "cold" periods...

Temperature definitely has a major affect on cycling times when temperatures are below 18 degrees C (65F) ....

Tell me about it...
try 9-13c but I got there in the end with no bottled snake oil,
though there was a fair bit of pond gunk!

Yep... I'm extremely dubious about the "bottled bacteria" ...

Here's my rationale.... the nitrifying bacteria (both types) definitely have an optimal temperature range, require food (ammonia/nitrites) and oxygen to grow...

Whack a batch in a bottle... leave in on the shelf, shake it, transport it, heat it, cool it...

Just really not sure that the contents would actually survive for any great length of time...

Aloha All

Here are answers to the questions posed about our startups:

1. DO in all systems at time of startup was 6.0-7.8 ppm, pH was 7.0, water temps 22-26 C, we do have solids settling tanks in the systems right after the fish tank, we've NEVER done a water exchange EVER during a year and a half, especially during system startup (except once when I made a stupid mistake, see the article on Startup in a future Backyard Aquaponics magazine. We only use about 50 gallons per day to make up for evaporation and transpiration, during extended drought periods only, other times rainfall tops up the systems so we don't have to. The ammonia levels don't seem to convert one-for-one to nitrite levels. When we had systems showing 1-2 ppm ammonia at inoculation, they showed 10 ppm nitrites three days later, and STILL showing 1 ppm ammo! We also put fish into one system and ammonia tablets to provide food for the bacteria, because it was cold and the fish weren't eating or metabolizing at first; that worked fine also.

2. We started our FIRST system without any bacterial inoculants because we didn't know they existed yet, didn't have an aquaponics system to steal seed water from, and so this system took 2-1/2 months to show nutrients (nitrites and nitrates).

3. We started our SECOND system with the cheap, $43/gallon, one-year shelf life at room temperature bacteria from Aquatic Eco in Florida, USA, and had nitrites within 3 days, nitrates within five days, and were planting 7 days after inoculation. This worked great after we figured out how to modulate the nitrite spike by removing shade (rafts and covers) off the tanks and troughs.

4. We tried to start our THIRD system with the $300, refrigerated, 90-day shelf life at 10 degrees C bacteria, and they had apparently expired, because we got no show of nutrients from this expensive inoculant after 7 days. So then we dumped in 400 gallons of system water from one of our other systems, and got the normal three-days-to-nitrites, five-days-to-nitrates experience we got with the $43 gallon.

Tropic is it legal to use those bacteria products in hawaii? I know that they won't bring them in for aquariums but maybe you have gotten a permit for commercial applications or the attitude of DLNR has changed.
I was glad to see that you got the same results just dumping in water from an existing system. When I set up my other systems I'll have to remember that.

If you have pre-existing system/system water to use, it is essentially the same thing as the stuff in the bottle except probably far better since you know it is still alive and fresh as well as being already groomed to your climate and water conditions.

Now my first system, cycling without fish during cool weather (mostly below 70 F) took only about 3 weeks. I didn't use any bacteria in a bottle but I did add a hand full of fresh worm castings (along with what ever worms were in there) to each grow bed. Now my system in this example was flood and drain gravel beds so I wonder if there is a benefit in bacteria establishment in such conditions since I know most people on the forum give an average of 4-8 weeks for cycling with fish and 2-4 weeks for fishless cycling.

Now I know that gravel beds are not likely to become the standard for commercial scale operations, especially ones that make their profit from salad greens, but I wonder if a single gravel filled flood and drain filter on the property might be handy to have as a small portion of a system (a place for growing a mother plant to take cuttings from or testing out other ideas) or if it would just be redundant.

I think gravel/aquaclay will always have a part to play in AP.
Works fine for me, but I can see the benifits of 'broad acre' Aquaponics

I disagree, I think that gravel grow beds will have a place in commercial scale operations- one of the reasons there is a large gravel grow bed in my system, just before the DWC raft ponds. One thing that gravel grow beds do, besides catching the fish waste and decomposing it, is that water ran through a gravel grow bed picks up 25% oxygen. That is free oxygen, in the point that it didn't cost anything to generate it- one of the parameters of my system is to see if that is enough oxygen to operate the DWC raft ponds or if additional aeration is required. Utilize free from nature as much as possible- gravity is another and so is using water's natural ability to equalize, even over great distances and even water striation may be used for different times of the year, to heat or cool a system naturally.

Angie, are your gravel beds gonna be flood and drain or constantly flooded?

To start with, my gravel grow bed will be flood and drain, probably 15 on, 45 off to start. As the stocking density gets to maximum capacity, I'll change this to 30 on and 30 off. Later this may change to continous, depending how well the fish do at greater stocking densities. This is a testing prototype and if I find it necessary to sacrifice my gravel grow bed to convert it to a continous flow trickle filter, then that is what I'll do. Right now, with the quanity of water that I'll have in my all tanks and the pump that I am thinking of getting, which pumps 98 gal a minute, I could do a complete water change in 30 minutes but the smaller tanks are for fingerlings, not production growth, so they'll need considerably less water changed out to maintain oxygen levels.