Be patient with water chemistry

[Kobus Jooste]

I have noticed a number of discussions lately, and have experienced my own experiments going in the same directions sometimes - a bit too much haste.  Mixing water is not like mixing paint.  Imagine you went to the paint dealer, asked to have a colour mixed up and then get told to wait two days to three weeks, depending on the type of paint, to see where the colour ends up.

 

Well that is a bit how water chemistry in closed recirculating systems should be approached.  Just adjusted your pH? The reading you are getting is not accurate yet.  Just fed your fish or had some cold days recently? Test over a couple of days to be sure about your DO.  I see the most common issues people address is pH and cycling of a new system.

 

In terms of pH, few people seem to test a range over a number of days to see what is going on in their system.  Depending on your water temperature, fish activity and alkalinity, it may take a number of days for the addition of new water or the adjusting of pH to fully manifest in the pH readings.  A case in point is an experiment I'm setting up to make sure that I know what an experimental mix of media is doing to my water chemistry.  I tested my rain water supply and it was 6.5.  I decided that this was too low and adjusted upwards until the immediate reading was 6.9.  This was left to stand for two days, after which the pH was 6.7.  Now if the experiment had started, I may have chalked up the initial shift to the media.

 

TC Lynx often warns people about testing well or tap water out of the tap immediately for similar reasons.  Any chlorides or CO2 in the water could affect your reading, thus let it stand for a bit or if you have to add to your water immediately, test the effects over a number of days.  I also suggest keeping track of a number of water quality variables and learning to understand the interrelationship between these if you are not familiar with them yet.  I check pH, temperature, alkalinity and DO in my system together, and break my TAN (Total ammonia nitrogen) count down into ionized and unionized Ammonia.  My system is extablished thus I do not test Nitrites or Nitrates very often, but if the fish behaviour or visible water quality changes, I will check everything.  I do not look at Hardness much, although it can also be a factor in water quality.

 

In terms of the cycling of a system, I think there are some basics that most people need to keep in mind:

1) The bacteria responsible for nitrification and de-nitrification are some of the slowest growing bacteria in nature.

2) The development of Ammonification (the breakdown of more complex nitrogen bonds back to Ammonia), and the two phases of nitrification (Nitrosomonas and Nitrobacter) reacts to spikes in the availability of the chemical they modify.  Thus you need a good source of step 1 chemicals before you will find any trace of step two.  These reactions are temperature and pH dependent, but can take as long as 40 days in suitable environments.  It is not advisable to try cycling a system when you are still trying to get the pH stable or if the temperature is very low.  Things will just take that much longer.  The pH should be in a range of 6.5 to 7.5, and the temperature is better above 65 degrees F if you are in a hurry.

3) any distruption in the flow of ammonia into the system will result in the eventual die-off of the bacterial cultures.  A baseline input of Ammonia must take place daily for the system to remain optimal.  This input can be sourced from fish or the breakdown of solids and old plant material in the system, but some flow of ammonia is vital.

4) just because you cycled on 4 fish, does not mean the system can take 40 now.  Each cycled system is a balance of water flow rates, filter size, media type and current nutrient loading.  Remember the slow-growing bacteria - if the nutrient input has been from 4 fish over an extended period of time, the bacterial cultures will adapt to that.  Same principle as worms in the bed.  You can toss in a million but the end population will match the nutrient supply.  If you cycled on a small fish population and want to increase your fish load, do it gradually.

5) the nitrification process is aerobic.  If your system has been down for more than 12 hours, worry, and if it has been down more than 24, you may want to consider your cultures to be in serious trouble.  Anaerobic respiration may now start surfacing in the system and you may have a disaster in waiting if you just fire it up as is.  Consider the nitrification capacity of your unit to be compromised and check water quality very carefully for a while.  If your DO plummets and / or ammonia and nitrite build up, you may just have to cycle again. 

[Kobus Jooste]

then just refer to aerobic nitrifying bacteria or something like that

Sylvia Bernstein said:

Ack!  I'm getting a headache....

I'm going to read through the stuff that Rupe sent then try to figure out a way to represent this that will be correct and relevant, but also not overwhelm anyone with science (not that I"m capable of doing that anyway ).  The book is geared at step by step instructions for the home gardener who probably only barely need to know these finer details.  

[TCLynx]

To tell you guys the truth, I usually don't bother to name the bacteria for general purposes.  When explaining the Nitrogen cycle I usually say.

"Well the ammonia spikes and there is an aerobic bacteria that shows up and converts it into nitrite which is also toxic to fish and as that spikes another aerobic bacteria shows up that will convert it into nitrate which is far less toxic and also happens to be something the plants can use."

 

This usually saves me since I can rarely pronounce let alone spell the tricky words and I'm just dyslexic enough that I hate trying.

[Shawn Cruze]

I am designing an independent research project to determine which bacterial species are required for certain aspects of water quality in aquaponic systems. Give it six months or so and I should be close to a definitive answer assuming all my trials go well. A variety of water and media samples from systems throughout Colorado would really help.

[Kobus Jooste]

Will you be seeding with any cultures or just setting systems up, cycle and then test to see what cultures dominate?  It would be really interesting to see these trials as they will likely also assist with HACCP classification of systems.  Many labs can only ID roughly - ie. gram negative bacillus or something like that - getting down to finer detail will be a good piece of hard work I presume.

 

Then potentially there will be new vs established and optimal vs. marginally performing systems to compare.  You could be busy for a while..........

Shawn Cruze said:

I am designing an independent research project to determine which bacterial species are required for certain aspects of water quality in aquaponic systems. Give it six months or so and I should be close to a definitive answer assuming all my trials go well. A variety of water and media samples from systems throughout Colorado would really help.

[Harold Sukhbir]

Hi Shawn,

Some researchers agree that Temperature, Localities, Water source etc.,and I'm sure even the types of fish feed and other inputs influence the predominant strains of Nitrifying bacteria present in AP systems and that they are always unique to various individual systems.Granted these studies are done for wastewater treatment, these results should be consistent with AP "sludge" as well. Since the science is evolving, all and any research would surely be welcomed.

[Sylvia Bernstein]

Hey Shawn, I'm in Boulder.  You are welcome to sample my sludge 

[Izzy]

Don't forget Nitrosococcus for those of us with brackish water!!!

[Izzy]

Actually, you are right on the money!!!  This is 100% true for the short term, but the long term effects will be specific to how the competing mechanisms come into play from specific strains of bacteria.  You can't really know the mind of mother nature (or God for that matter)! LOL

Harold Sukhbir said:

Hi Shawn,

Some researchers agree that Temperature, Localities, Water source etc.,and I'm sure even the types of fish feed and other inputs influence the predominant strains of Nitrifying bacteria present in AP systems and that they are always unique to various individual systems.Granted these studies are done for wastewater treatment, these results should be consistent with AP "sludge" as well. Since the science is evolving, all and any research would surely be welcomed.

[Sylvia Bernstein]

Rupert,

I just read your article and I'm now convinced.  Nitrospira it is!  thanks again for pointing that out.

 

RupertofOZ said:

Sylvia, you can download the original paper by Hovanec from here... http://aem.asm.org/cgi/content/full/64/1/258 ... or directly from... http://aem.asm.org/cgi/reprint/64/1/258

 

There's also a list of references included in the article I wrote on the subject for BYAP mag #5.... email me if you want the whole article and list of references...

 

Here's a couple of other references...

 

A paper by Altmann... http://www.ncbi.nlm.nih.gov/pubmed/12919415?dopt=Abstract

 

A paper by Daims ... http://aem.asm.org/cgi/content/full/67/11/5273

 

A paper by Kim DJ... http://www.ncbi.nlm.nih.gov/pubmed/15927463?dopt=Abstract

 

And some other links... http://www.microbial-ecology.net/googlesearch.asp?cx=01204887656811...

 

Sylvia Bernstein said:

Re: Nitrospira vs Nitrobacter.  Dr. Wilson Lennard actually corrected me on that when he reviewed parts of my book and said just the opposite...that they are Nitrobacter in AP systems.  Are you sure?  Good thing I'm in the process of a final review of the copy edits now!  (I did that emoticon just for you, Harold!)

[Izzy]

FASCINATING