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I'm running through Sylvia's "Aquaponic Gardening" book and trying to understand the cycling process... as far as I understand the process...

1) abundant Urea breaks down into Amonia over time on its own through percolation

2) abundant Amonia attracts Nitrosomonas bacteria which results in Nitrites

3) abundant Nitrites attracts Nitrospira bacteria which results in Nitrates

4) steady and manageable levels of continuously converting Amonia and Nitrites will produce an "end result" steady supply of Nitrates which is not harmful to fish, and beneficial to plants.

sooo if you continue to cycle I'm guessing that there is some form of bacteria that will eventually feed on the excessive levels of Nitrates resulting in yet another compound... basically I'm wondering what happens if you "over-cycle" your system instead of adding the plants that will take out the Nitrates?

or does it just simply make your water increasingly fertile?

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Sorry brad, my fat fingers on a small keyboard again, that's a 2% solution of bleach.  Sorry for the typo
 
Brad Moreau said:

Leo 

20% chlorine bleach of 550 gal ft thats 110 gals bleach or 1/2 is 55 gals bleach ? maybe drain complete & recycle

Leo White Bear said:

IMHO- I would by-pass running the water through the grow bed and bio filter because upon dieing the decomposition of the algae will deplete the oxygen levels in the water and may cause anaerobic areas in the grow beds.  You will discover this when the grow beds and bio filter start to small bad.  If you have a really bad growth of algae, cut off all light, darkness will kill off the algae and their spores.  A little bit of algae is not really much of a concern but the high nutrients may invite a green slime that will choke off everything.

  To really clean out the algae, I would do a water change and treat the original FT water with chlorox bleach at a 20% concentration.  With running an air bubbling system through this treated water, the chlorine will be dissipated within a few days.  Be sure that if you do this, check the chlorine concentration before you decide to return this water to your system, any chlorine WILL kill all your plants and fish.

  There is a product that works well with HTPE IBC totes, made by Krylon to paint plastic.  It deos work well but you must wait for it to throuly dry or it has a tendance to scrape off.

  If you are collecting rain water and diverting it into a rain barrel, could you instead, divert it to an IBC for replacement water?  This way you will never have to aerate to rid your water of chlorine.

thanks Leo, I though that was a little high

Leo White Bear said:

Sorry brad, my fat fingers on a small keyboard again, that's a 2% solution of bleach.  Sorry for the typo
 
Brad Moreau said:

Leo 

20% chlorine bleach of 550 gal ft thats 110 gals bleach or 1/2 is 55 gals bleach ? maybe drain complete & recycle

Leo White Bear said:

IMHO- I would by-pass running the water through the grow bed and bio filter because upon dieing the decomposition of the algae will deplete the oxygen levels in the water and may cause anaerobic areas in the grow beds.  You will discover this when the grow beds and bio filter start to small bad.  If you have a really bad growth of algae, cut off all light, darkness will kill off the algae and their spores.  A little bit of algae is not really much of a concern but the high nutrients may invite a green slime that will choke off everything.

  To really clean out the algae, I would do a water change and treat the original FT water with chlorox bleach at a 20% concentration.  With running an air bubbling system through this treated water, the chlorine will be dissipated within a few days.  Be sure that if you do this, check the chlorine concentration before you decide to return this water to your system, any chlorine WILL kill all your plants and fish.

  There is a product that works well with HTPE IBC totes, made by Krylon to paint plastic.  It deos work well but you must wait for it to throuly dry or it has a tendance to scrape off.

  If you are collecting rain water and diverting it into a rain barrel, could you instead, divert it to an IBC for replacement water?  This way you will never have to aerate to rid your water of chlorine.

All are right but I would also add ... save yourself some real grief and go to Aquarium Co. and buy Basic Tester Kit, about $25.00. Also buy a Nitrite Test Kit for $10.00 more. These will give you pH, Nitrate and Nitrite testing capabilities. Test returning water for pH and Nitrates. If Nitrates are high add more plants and speed up cycle a little, no sense in leaving food for plants on the table. Then go to Main Tank and test for pH and Nitrites, If Nitrites are high, slow cycle down a little. remove a few fish until you get the feel for where your comfort level is on how many fish you want, how fast you want to cycle, or how many plants you want.

DO NOT BLEACH YOUR SYSTEM TO COMBAT ALGAE!!! EVER!!!!

Sorry for all the shouting, but that needs to be clear to all readers of this thread. Algae is generally healthy, and natural to every body of water on the planet. If you have algae in excess, block the light, add algae eaters, and keep aeration high, especially at night in hot weather. Yes, algae adds to total oxygen demand. Yes, algae increases the day/night pH swing. Yes, an extreme bloom of algae can even cause fish death, and it certainly does in nature because there are no big airstones maintaining DO. But seriously? Bleach? That would destroy all fish, bacteria, worms, plants, and any progress in N cycling, and accomplish no permanent aid in reducing algae at all without fixing the cause of the extreme algae in the first place. Brad, reduce light, increase aeration, and stay the course. It will all cycle fine and harmless, and some algae eaters (mossambicus tilapia, goldfish, koi, plecos, etc) will enjoy the meal. In an extreme algae case, dump the water, or divert it to a storage tank and re-introduce the water when algae is dead and settled. 

William, to answer your original post question...yes, nitrates may convert to something else by bacterial action under certain conditions, and the practice is common and familiar in aquaculture, including many aquaponics systems designed around the UVI model, which of course is more aquaculture than aquaponics. It is called Denitrification (not surprisingly).

In aerobic conditions, nitrate NO3 is the final form, and will continue to build in the system until something removes it. Though it is less harmful by far than nitrite NO2 or ammonium NH4, nitrate is still toxic to fish at high levels, and some fish are more tolerant than others.  In anaerobic conditions, there are groups of bacteria that convert NO3 to N2, also known as atmospheric nitrogen because, you guessed it, N2 is 78% of the air we breathe. Recirculating aquaculture has tools to remove the solids, and biofilters to convert the ammonia to nitrates, but eventually the nitrates would accumulate to toxic levels for the fish. So...they allow a portion of the water to settle in total calm and go anaerobic, where bacteria do the job of denitrification. This happens in the settling tank in the UVI model. Next in line is the degas tank, where air is liberally boiled into the water, to remove the resulting N2, CO2, and that nasty hydrogen sulfide (a quite toxic product of anaerobic respiration), as well as to re-oxegenate the water before going to plants or back to fish. In low density aquaponics, we want to keep our nitrates for plant fertilizer, and we can skip the anaerobic and degas zones. 

Here is a clip from Wiki: 

Denitrification takes place under special conditions in both terrestrial and marine ecosystems.[14] In general, it occurs where oxygen, a more energetically favourable electron acceptor, is depleted, and bacteria respire nitrate as a substitute terminal electron acceptor. Due to the high concentration of oxygen in our atmosphere denitrification only takes place in anoxic environments where oxygen consumption exceeds the oxygen supply and where sufficient quantities of nitrate are present. These environments may include certainsoils[15] and groundwater,[16] wetlands, oil reservoirs,[17] poorly ventilated corners of the ocean, and in seafloor sediments.

Denitrification generally proceeds through some combination of the following intermediate forms:

NO3 → NO2 → NO + N2O → N2 (g)

John-

  If you re-read my reply, I stated that a water change should be done to remove as much spore as possible and treat with the 2% chlorinesolution, but to be sure that the chlorine HAS COMPLETELY been dissipated before returning any water to the FT as any chlorine WILL KILL PLANTS AND FISH, this portion of my reply is in perentices below for easy referrence.

  You CAN use bleach IF YOU ARE CAREFUL.

 

 " To really clean out the algae, I would do a water change and treat the original FT water with chlorox bleach at a 20% (typo - correction is 2%) concentration.  With running an air bubbling system through this treated water, the chlorine will be dissipated within a few days.  Be sure that if you do this, check the chlorine concentration before you decide to return this water to your system, any chlorine WILL kill all your plants and fish."

Jon Parr said:

DO NOT BLEACH YOUR SYSTEM TO COMBAT ALGAE!!! EVER!!!!

Sorry for all the shouting, but that needs to be clear to all readers of this thread. Algae is generally healthy, and natural to every body of water on the planet. If you have algae in excess, block the light, add algae eaters, and keep aeration high, especially at night in hot weather. Yes, algae adds to total oxygen demand. Yes, algae increases the day/night pH swing. Yes, an extreme bloom of algae can even cause fish death, and it certainly does in nature because there are no big airstones maintaining DO. But seriously? Bleach? That would destroy all fish, bacteria, worms, plants, and any progress in N cycling, and accomplish no permanent aid in reducing algae at all without fixing the cause of the extreme algae in the first place. Brad, reduce light, increase aeration, and stay the course. It will all cycle fine and harmless, and some algae eaters (mossambicus tilapia, goldfish, koi, plecos, etc) will enjoy the meal. In an extreme algae case, dump the water, or divert it to a storage tank and re-introduce the water when algae is dead and settled. 

I know, Leo, what you said was technically correct, but at least two people on the forum have taken away from your post to bleach their system. Brad called me directly, and another posted a thread on bleach directly from your advice. Bleach is not a fix for algae, and that is not clear from your post. I'd compare it to radiation and chemo-therapy to treat a splinter.

I mean no offense, brother, but the forum users need clarity on the subject.

William-
Sooner or later your fish will die, they will succum to NITRATE poisoning. Although it is stated that nitrates are not harmful to fish, in high levels they are. somewhere around 200 - 250ppm will start to harm your fish. They will act as though they have been poisoned by amonia, they will start to act erratically, swim in circles, and slowly die. At the levels we are concerned with in aquaponics everything will go well - so in answering your question "can you over-cycle your system" if you do not keep the nitrates in check by adding additional plants - Yes.

Hi William,

Well as you can see from the discussion this far there are many different approaches to solve problems within Aquaponic systems. The important thing is to get a firm grasp on the principles involved and their implementation/purpose and effects, which I think was done in great detail by both Jon and Leo

great information from all involved, thanks a lot everyone for answering my noobish question

Here's my two cents on algae.

Make sure you have plenty of aeration especially overnight.

Block light from the water, this will eventually kill algae.

Let the algae get pumped into any media beds or media based filtration where it can decompose.

I would NOT do water changes to deal with algae in an aquaponics or pond system.  See the decomposing algae in the filtration can actually give off compounds that help inhibit future algae blooms.  Well at least helps inhibit green water.  I don't think there is really anything all that effective against algae on surfaces or the string algae other than blocking light from the tank.

I wouldn't worry about a little bit of algae decomposing in some media beds in a brand new system causing any sort of anaerobic conditions.  You would need some pretty heavy matts of algae clogging a bed to cause anaerobic conditions pre plants or fish.

And get some plants in there

While "over cycling" may not technically be a problem, you don't necessarily want to be elevating your nitrates off the chart when there are no plants to use it.  And you probably should get some more complex nutrients going into the system before too long since ammonium chloride is not a complete fertilizer the way fish food is.

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