Lets put this to rest: Do large water changes have a negative effect on Nitrifying Bacteria / BB

[RD.]

Grinch - I was the one to initially use the term unstable, to which Kolt asked me; "And what would you call unstable water conditions?". My post was in response to his question. It's all good, but it was your miss, not mine.

Kolt - there are a couple of old threads kicking around on TDS that I have posted in (if search is working?) that explain how TDS works in an aquarium, and how it affects the osmoregulatory system in fish.

 

[Grinch]

Pheromones
Pheromones are hormones which act externally, hormones are contained within the body and affect the body from within. Pheromones can affect the body when in the local environment rather than in the body itself.

Fish release growth inhibiting pheromones which limit their growth and the growth of other fish in the same environment. If these pheromones are allowed to build up in a closed system then they will have an impact on growth.

In a small body of water they are likely to be present at higher concentrations because there is less water to dilute them. Water changes are the best way to control the level of these pheromones.

Reference?

 

[philipraposo1982]

http://www.fishtanksandponds.co.uk/aquarium-science/fishgrowth-tanksize.html
http://www.wetwebmedia.com/fwsubwebindex/GrwLmtChems.htm


something else to consider:
http://www.seriouslyfish.com/stunted-growth-means-stunted-lives/

 

[RD.]

I believe that the correct term (because the science isn't totally clear) is growth inhibiting substances.

 

[skjl47]

been under the impression that in general the amount found outside the filter is negligible.

Hello; I am a bit curious as to the mechanism of this if it is indeed correct. I get that there is always good water flow thru a running filter so the ammonia/nitrites in the tank should be accessed. However it seems that in creating the flow thru a filter that the water in the rest of the tank is also in motion to a degree equal to the gph of the filter. It seems to me that on many other surfaces where water flows there should be the opportunity for the bb to colonize. Maybe a higher concentration on the filter surfaces due to the more concentrated flow, but it does not seem right that the bb population outside a filter will be negligible.


The quotes that follow were picked by me as I read thru the thread. I have nothing to add to them. I think they fit the discussion well.

If your tap water is unstable, then anything is possible

typical conditions, what one might describe as normal - massive water changes are a non issue with one caveat - this should only be done on an established system, with established filters.

Unstable water would be water with a low buffering capacity. If your water is soft (i.e. has low kh/gh), it is subject to large pH swings. Anyone using RO water has to be careful with this.

but local tap water is something that every hobbyist has to figure out on their own

In fact, pH swings are usually not the issue, but swings in TDS (total dissolved solids) can be. A huge swing in TDS is what causes osmoregulatory stress, not changes in pH

reason why large water changes are important which many don't know about.

Pheromones

 

[Drstrangelove]

Read my links from the first few posts. its in there. Its actually true believe it or not..

If your ph is sub 6 you will have a near impossible time cycling a tank. the nitrifying bacteria will not grow and become established.

You posted:

".....frequent water changes are important to prevent ph from crashing which will kill the bacteria if its begins to drop below 6."

I asked you where anyone says it dies. Your answer was: "Read my links..."

Your links say nothing of the sort. They describe nitrification inhibition. But, inhibited nitrification doesn't mean death.

"Inhibition is temporary short-term or long-term loss of enzymatic activity."
http://www.ecos.ie/wastewater-nitrification-how-it-works/

Inhibition is loss of cellular activity, similar to what some bacteria experience when frozen. They aren't dead, which is why when meat is thawed, it still needs to be cooked thoroughly. But the bacteria isn't duplicating while it's in the freezer. Inhibition doesn't mean dead. It means a partial or total loss of nitrification ability... which may be temporary.

Keep in mind that these bacteria survive in the soil at pH as low as 3.7. It's therefore, imo, incorrect to suggest that a pH level below 6.0, will wipe out someone's BB, unless you can post evidence of that.

 

[Drstrangelove]

Hello; I am a bit curious as to the mechanism of this if it is indeed correct. I get that there is always good water flow thru a running filter so the ammonia/nitrites in the tank should be accessed. However it seems that in creating the flow thru a filter that the water in the rest of the tank is also in motion to a degree equal to the gph of the filter. It seems to me that on many other surfaces where water flows there should be the opportunity for the bb to colonize. Maybe a higher concentration on the filter surfaces due to the more concentrated flow, but it does not seem right that the bb population outside a filter will be negligible.


The quotes that follow were picked by me as I read thru the thread. I have nothing to add to them. I think they fit the discussion well.

For BB, population growth and nitrification ability are assumed to follow the normal pattern that all biofilm bacteria follows:

Surfaces are superior to free floating
Rough, porous surfaces are vastly superior to smooth

This would imply that the glass, the water, and any ultra smooth surfaces in the tank are relatively poor sources for BB as opposed to a sump, cannister, etc..

But it gets worse. With regards to glass, another factor is that large areas of the glass do not get a large water flow, thus having low oxygen and low nutrient.

And even worse.... darkness apparently is a preference for some forms of BB. The darkest areas area everywhere but the glass and the water.

 

[Drstrangelove]

Hello; I am a bit curious as to the mechanism of this if it is indeed correct.

Having said all of that, I agree. I'm still curious.

I've yet to find a study that actually tries to quantify the amounts of BB in the various parts of a tank in way. Not even in a systematic way, just some sort of raw calculation or SWAG.

So, one is left with guesswork, assumptions, and whatever evidence we can use to create a theory.

 

[robham777]

At a ph value of 6 or less most free ammonia NH3 would be ionized into ammonium NH4+. If the beneficial nitrifying bacteria can not process ammonium into nitrite then reduced food source would be the inhibiting factor. TAN (total ammonia nitrogen) would increase since it is not being converted. I assume over a prolonged period of time the bb would die off to match the level of NH3 present at a given ph value.

 

[Gourami Swami]

I have never been a fan of huge water changes personally, I prefer to do more frequent smaller water changes. In general I do two 30% water changes a week, sometimes I will slack and do one 40% or so WC a week. One reason I prefer this is that I use cold water. Heated water coming out of the faucet supposedly contains much higher percentages of heavy metals than cold water, as it is heated in metal boilers. If I were to do a 90% water change with cold water, my fish would probably go into shock and die. at 30-40%, the temperature dips a few degrees for an hour or two and then bounces back. While working at an aquarium store, I noticed too that many people who came in complaining about fish dying constantly, or their cycle not being stable, often did large water changes. I'm sure large water changes can be done properly without disrupting the tank, but for novices or people who don't sit around testing their tap water before a change (most casual aquarists), I tend to think smaller changes have much less room for error, and thus I usually recommended no more than 40% at a time, onc