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

[Grinch]

I do bi-weekly 75-80% WC's. Which works out to roughly "fin level" as others have mentioned above. I pre-mix tap water with prime before it goes out to the tanks. Pre-mix is not aging, but I believe it is an important step in ensuring both the fish and BB in the tank do not get thermally or chemically shocked by the new water.

But from what you and Chockful said am I correct in gathering that areas with low PH tap water would indeed possibly have issues doing such large water changes? And what would you call unstable water conditions? Would it be a common enough issue that the average aquarist might run into it? Or is it rare to have unstable water condition out of tap? What about out gassing caused by the tap water being under pressure. Is it also a concern when doing such a large change?

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.

I don't think this is an issue that "science can settle" because the water coming out of the tap, methods to treat the water, and desired outcome in the tank varies so much between fish keepers. Instead, we might try to develop "best practices" advice on water changes.

 

[RD.]

Unstable could mean all sorts of things, but local tap water is something that every hobbyist has to figure out on their own - and hopefully not the hard way.

pH is not an issue keeping discus, unless one is breeding. A local breeder used pretreated tap water (not aged - it's chloramine treated) from a large storage vat, but unless he was breeding, all of his tanks (2-3 thousand gallons worth), including grow out tanks were at pH 7.8-8.2.

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. This has all been well documented.

Water changes really comes down to bio load, my tanks are all very low in stock, so I only perform them once a week, but when I do it's a big one. The real key IMO is ensuring that the water parameters going in, are very similar as the water going out. In that case, no amount of new water is too much.

 

[Grinch]

Unstable could mean all sorts of things, but local tap water is something that every hobbyist has to figure out on their own - and hopefully not the hard way.

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. This has all been well documented.

This does not mean that best practices cannot be developed.

A huge swing in anything is potentially harmful to both the fish and the BB. TDS and pH are both important considerations. As is temperature, for instance.

 

[pops]

go big or stay home. any thing worth doing is worth over doing , better to much than not enough, never leave a job half done. ok, enough of that.

I do nothing but fin level water changes. have for years. never an issue, and i get plenty of time to vacuum the pee out of the gravel every time.

I add safe straight to the tank and then fill.

 

[RD.]

I never said that best practices cannot be developed. I've already developed mine, to suit my needs, many years ago.

But best practices includes that each & every person performing the water changes understands their local tap water, and clearly many on MFK don't. Many cannot tell you what their tap water disinfectant is (chlorine or chloramine), and/or what the residual is at their tap. They fail right off the bat, by either using too little conditioner, too much, or the wrong kind. Sadly this is also all well documented.


My post here was only to clarify the OP\s concern, or question on the subject. What everyone else does, or does not, is up to them, based on their personal tanks/fish/ tap water and manner in which they perform their regular maintenance.

 

[Drstrangelove]

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

I've never seen this. BB will become inhibited below 6.0 in liquids (not until under 4.0 in soil), but they survive in water at least down to 5.0-5.5, and perhaps lower.

Can you post your source claiming BB start to die below 6.0?

 

[koltsixx]

Fish Tank Travis thanks man, for adding your experiences.

Grinch thanks for your experiences and explanation as well.

RD. thanks for adding your knowledge also. Your contributions are always valuable.

pops and thank you for your contribution.

Drstrangelove I also appreciate your contributions as well.

Seriously gentlemen, thank you. I appreciate the knowledge you put forth and hope I've taken away a better understanding because of your efforts. I have said it many times before, I consider myself a novice when it comes to fishkeeping so I appreciate when my understanding of the hobby is improved by learning from my fellow MFK members.

I will honestly say I did not know there was a correlation between low PH and Beneficial Bacteria and my understanding of TDS is limited. So I also did not know TDS swings could cause osmoregulatory stress in fish. I only started learning a little about TDS when I was considering some stock from Wes, Rare Fish; specifically Colomesus psittacus. I opted out of buying the fish as I did not want my limited understanding to possibly cost the fish it's life.

The truth is the premise of this thread is slightly skewed from the original debate but I more or less rolled with it but I digress. If I'm understanding things better now(which I might not be, lol) Simply stated in general large water changes are no threat to Beneficial Bacteria in most instances but one should know the qualities of their specific water source to be sure as there are rare instances where they may present a problem. And as RD. said the key being to make sure the parameters of the water going in is very similar to that which is going out.

With that said it maybe time to expand my knowledge of TDS as I can't expect you guys to hand feed me everything I should take some responsibility for myself.

 

[Grinch]

My post here was only to clarify the OP\s concern, or question on the subject.

I assumed you were talking about my post because you referenced unstable water and it appeared immediately after my post. Use of the quote button would help clear up these issues in the future and help to prevent miscommunication.

 

[philipraposo1982]

I've never seen this. BB will become inhibited below 6.0 in liquids (not until under 4.0 in soil), but they survive in water at least down to 5.0-5.5, and perhaps lower.

Can you post your source claiming BB start to die below 6.0?

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.

I guess the initial point I was trying to insist on is that in no way can you physically remove the beneficial bacteria from your aquarium through water changes or vacuuming the substrate. Even some scrubbing won't do the trick. There is plenty of scientific proof of this and this is something I want to stress as many hobbyist seem to think otherwise.

As far as stable water conditions goes this brings up a whole whack of variables. But first I want to say that assuming your tap water, once treated is appropriate for your live stock then by doing frequent large water changes you are actually ensuring that there are no swings / shift in your aquariums parameters. They will remain stable with that of your tap water which is the best case scenario.

Also keep in mind changing large quantities of tank water will offer other benefits to your livestock as well as ensuring your ph/gh/kh will remain stable.

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

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.

 

[Grinch]

Simply stated in general large water changes are no threat to Beneficial Bacteria in most instances but one should know the qualities of their specific water source to be sure as there are rare instances where they may present a problem. And as RD. said the key being to make sure the parameters of the water going in is very similar to that which is going out.

With that said it maybe time to expand my knowledge of TDS as I can't expect you guys to hand feed me everything I should take some responsibility for myself.

Knowing the attributes of your source water on a typical day is by far the most important factor to consider, as this will dictate how you should treat your water for your fish. The parameters going in should be "similar" as to that going out. For instance, you want nitrate to be as low as possible going into the tank while the effluent leaving the tank is typically much higher. The danger with big water changes, and any water change actually, is that you accidentally stumble into the atypical day for your water treatment plant etc.