Water Changes

[Meyer Jordan]

I did find that the experiment that this paper (McMurtry, M.R., P.V. Nelson, D.C. Sanders and L. Hodges. 1990 a. Sand culture of vegetables using recirculating aqua cultural effluents. J. of Applied Agricultural Research; Vol. 5, No. 4, pp. 280-284.) involving the iAVS system was conducted using a quite low fish density.
(Costa-Pierce,Soemarwoto) determined that the optimal aquaculture stocking density for highest growth for common carp (Cyprinus carpio) was 6.0 kg/m3. In this described experiment the stocking density was 1.68 kg/m3. Less than a third of optimal density, which translates into less than a third of Ammonia, Nitrite, and Nitrate levels. If optimal fish density had been used, the above mentioned pollutants could very well have reached toxic levels. One way to get the results you want. Manipulate!

 

[Meyer Jordan]

I would also add that the feeding regime for this study was 3% of total fish weight per day. This is considerably less than the 7% - 10% of body weight required to sustain growth. This 3% was reduced to 1% later in the study. This is hardy a maintenance diet for any specie of fish. Even with this extremely low feeding level Ammonia and Nitrite was detected at levels that would have been problematic at higher pH and temperature..

 

[crsublette]

I would also add that the feeding regime for this study was 3% of total fish weight per day. This is considerably less than the 7% - 10% of body weight required to sustain growth. This 3% was reduced to 1% later in the study. This is hardy a maintenance diet for any specie of fish. Even with this extremely low feeding level Ammonia and Nitrite was detected at levels that would have been problematic at higher pH and temperature..

7~10% maybe for when the fish are young, but not as they grow bigger. (http://www.fao.org/docrep/s4314e/s4314e09.htm)

I can't remember why it was reduced to 1% later in that study.

They don't increase their pH very high at all and this is the kicker... The waste mineralization and ion exchange involved with plants nutrient uptake is what counteracts the nitrification acids and helps keep the pH at a particular quite low range...

Yeah, if they raised the temperature and pH higher, then that ammonia would be more toxic. However, the supporters state that, if pH does go up, then also the nitrification conversions rates will increase so the ammonia won't be as high so the ammonia won't ever be a problem.... Truth to some of it, but not just pH and temperature alone that helps nitrification conversion rates... I just wish there were longer trials.

 

[crsublette]

Personally, I would never advocate ammonia levels to get as high as they did in those studies. Beginners would especially not understand this and a simple screw up could lead to that ammonia killing their fish.

I was given alot of grief by people for expressing that....

 

[Meyer Jordan]

7~10% maybe for when the fish are young, but not as they grow bigger. (http://www.fao.org/docrep/s4314e/s4314e09.htm)

I can't remember why it was reduced to 1% later in that study.

They don't increase their pH very high at all and this is the kicker... The waste mineralization and ion exchange involved with plants nutrient uptake is what counteracts the nitrification acids and helps keep the pH at a particular quite low range...

Yeah, if they raised the temperature and pH higher, then that ammonia would be more toxic. However, the supporters state that, if pH does go up, then also the nitrification conversions rates will increase so the ammonia won't be as high so the ammonia won't ever be a problem.... Truth to some of it, but not just pH and temperature alone that helps nitrification conversion rates... I just wish there were longer trials.

I stand corrected. I looked at the wrong chart before I stated that. The chart that I was citing contained feeding levels for 'brooders'. However, all of my other references indicate 4% - 5% of body weight for a 10" carp.
I do not understand the statement that "if pH goes up, then also the nitrification conversion rates will increase". What is this based on? It may apply in soil, but has little application in aquatic biofilms as the pH near the surface of the biofilm remains fairly constant.

 

[crsublette]

I do not understand the statement that "if pH goes up, then also the nitrification conversion rates will increase". What is this based on? It may apply in soil, but has little application in aquatic biofilms as the pH near the surface of the biofilm remains fairly constant.

I have come across many aquaculture biological filtration papers stating, in an aquatic environment, the higher ammonia removal rates (grams per day per m2) when pH is closer to around 7.2~7.8 and with notable carbonate alkalinity. I don't have anything off hand right now that I can reference.

Ya can still have a high ammonia removal rate at lower pHs, just need more surface area.... and this is where the iAVS supporters chime in how the surface area is the reason why it is effective.

 

[crsublette]

I have come across many aquaculture biological filtration papers stating, in an aquatic environment, the higher ammonia removal rates (grams per day per m2) when pH is closer to around 7.2~7.8 and with notable carbonate alkalinity. I don't have anything off hand right now that I can reference.

Did a quick google to see what Dr. Ebeling wrote on the matter...

slide 16 in the below presentation

https://ag.arizona.edu/azaqua/ista/...ofiltration-Nitrification Design Overview.pdf

 

[crsublette]

Ya can still have a high ammonia [removal] rate at lower pHs, just need more surface area.... and this is where the iAVS supporters chime in how the surface area is the reason why it is effective.

Grrr... quick late correction... noted in brackets above and now corrected in my previous post...

 

[Meyer Jordan]

Did a quick google to see what Dr. Ebeling wrote on the matter...

slide 16 in the below presentation

https://ag.arizona.edu/azaqua/ista/ISTA7/RecircWorkshop/Workshop PP & Misc Papers Adobe 2006/7 Biofiltration/Nitrification-Biofiltration/Biofiltration-Nitrification Design Overview.pdf

This is what is stated-
"The effect of pH on the nitrification rate for biofilters has been researched for more than sixty years, yet there is a wide range in reported pH optima (Biesterfeld et al., 2001). This suggests that the history and condition under which the bacteria are cultured may affect their response to pH
(Kaiser & Wheaton, 1983). The most recent results suggest that the optimum range of pH for nitrification can range from 7.0 to 9.0 (Haug and McCarty, 1972; Chen, et al., 2006). The
optimum pH for Nitrosomonas ranges from 7.2 to 7.8 (Loveless & Painter, 1968, Antoniou et al. 1990) and from 7.2 to 8.2 for Nitrobacter. Nitrifying biofilters have been operated over a much broader range from 6 to 9, due to the adaptation of the bacteria in a filter to actual operatingconditions. It is probably a good idea to maintain pH near the lower end of the optimum pH for the nitrifying bacteria to minimize ammonia stress on the cultivated fish species. In addition,
rapid changes in pH of more than 0.5 to 1.0 units over a short time span will stress the filter and require time for adaptation to the new environmental conditions."
The author without directly addressing the effect of high pH of oxidation rates cites the ideal pH ranges of nitrifying bacteria, but adds the caveat that nitrifying bacteria "adapt" to whatever environmental conditions they encounter. I am prone to agree with this assessment.
As relates to other studies, a quick search reveals that there is some disagreement on what, if any, effect environmental pH has on aquatic nitrifying biofilm. It warrants further research on my part.

and this is where the iAVS supporters chime in how the surface area is the reason why it is effective.

The importance of total SSA is well known, but when this SSA is only exposed to the pollutants in the water column for 25% of the time it is only going to be 25% effective.

 

[crsublette]

Yep, I think we're mostly agreeing.

I do find odd that, alongside nitrification adapts to its environment, then there is any optimal pH ranges for nitrification at all.

Also, odd in saying nitrification adapts to its environment yet, if there is no environmental pH impact on nitrification, then why must be there be any adaptation since it does not impact nitrification.

This reminds me of reading an aqualture engineer talking about how, to diagnose a parasite problem in his eel culture tanks, he lowered the tanks pH to 5.0. He describes the ammonia removal rates quickly fell resulting in a on increase of ammonia, but, after a few weeks, the ammonia started to fall back down.

Now... whether the rates are changed per SSA unit one way or the other... there is an environmental pH impact on the organisms and the organisms impact the nnitrification rate..

 

[Meyer Jordan]

there is an environmental pH impact on the organisms

Apparently there is no consensus on how small or great this impact may be and what other factors are players. Let the career researchers 'duke-it-out'.

 

[barryian]

Question? This is appropriate for the "Water Changes" subject ....
We've all done this. I haven't in about 10 or 15 years, though. I through the hose in to top off
the pond. Painter asked me to help him with something. Guess what? I had that hose running anywhere from 30 -60 minutes. That equates to 500 gallons, no more, hopefully less, going into a 2000 gal pond. The water overflow goes into my dry-well. As soon as I shut the hose, I added a dechlor for the full pond dosage .... Good thing is, I didn't empty 25%, then forgetty aboud id ...lol

Should be ok, RIGHT? !!! T^&%$@#$&&*)(_)&&*%%# So far, the only floaters I have are in my left eye!

Any thoughts ?

 

[Meyer Jordan]

Question? This is appropriate for the "Water Changes" subject ....
We've all done this. I haven't in about 10 or 15 years, though. I through the hose in to top off
the pond. Painter asked me to help him with something. Guess what? I had that hose running anywhere from 30 -60 minutes. That equates to 500 gallons, no more, hopefully less, going into a 2000 gal pond. The water overflow goes into my dry-well. As soon as I shut the hose, I added a dechlor for the full pond dosage .... Good thing is, I didn't empty 25%, then forgetty aboud id ...lol

Should be ok, RIGHT? !!! T^&%$@#$&&*)(_)&&*%%# So far, the only floaters I have are in my left eye!

Any thoughts ?

I resemble that remark!

 

[barryian]

I resemble that remark!

Which remark? Hope that was a joke ...lol ...

 

[Meyer Jordan]

Which remark? Hope that was a joke ...lol ...

Translation-"Yea, I've done this too!"