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

[RD.]

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.

I think that the key word is, supposedly. My cold supply line drops down into the 40's for much of the year, kind of rules out just using the cold supply only. Never once had any issues, even with 10-20 year old hot water tanks. Most of those same heavy metals are found in the local rivers and lakes. In some of the lakes in SA/CA etc they would also contain mega tons of human waste. IMO mixing warm & cold is a non issue for the vast majority of fish keepers. Millions of hobbyists perform water changes mixing both lines to reach a proper (within a few degrees) fill temp.

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

Yes, classic sign of folks who don't know their tap water - I would hazard a guess that 99% of those same people also had no idea as to what the disinfectant level was coming out of their taps. That, and many probably had fairly new set ups, and/or underdeveloped filter BB hence the reason that the cycle in their tank was not stable.

But this is MFK, not an entry level beginners fish forum for folks that don't know the basics. I hope .....

If I worked at a LFS I would also not advise 80-90% water changes, not with a customer base where the vast majority of people barely understand the basics.

 

[duanes]

When I worked as a chemist/microbiologist for a water company, we tested our pipes in the distribution system for bacteria, and found large colonies living as biofilm on the inside of the pipes (we disinfected with 1.5 -2ppm chloramine, which actually helped these ammonia consumers to live by providing food).
I believe its ridiculous to think water changes will harm them, as long as reasonable precautions are taken.
And because these bacteria are sessile, meaning they live on surfaces, and not free flowing as plankton, they are not removed by simple water changes.
And by vacuuming, some of the older weak bacteria may be removed, but that allows the more robust colonies to perpetuate.

 

[cichlidfish]

I think there are so many variables involved. Tap water, stock, filtration etc...basically if you test your tap and tank water often, you will find what works. Some tanks don't require huge water changes. If I kept a guppy in a 200g, I wouldn't need 90% water changes lol. The important thing is you find what works for you and the fish are healthy.

 

[philipraposo1982]

The idea behind this thread is not to necessarily promote huge water changes but rather to debunk some things about beneficial bacteria in our aquariums. Mainly, that they cannot be removed through large water changes and that they can and do multiply very quickly in the right conditions. Which I believe at this point we have done just that and more. Great input from everyone and I hope some newer hobbyist have a chance to see this and learn from it.

 

[RD.]

Totally agree, cichlidfish, but this thread really wasn't about what each persons best practice is, or should be. It was about how or if large water changes have a negative effect on the BB in an aquarium. The answer is; not under normal/typical conditions.

I'm fine with those that prefer to do 20% water changes daily, or whatever it takes to get the job done for them, but large frequent water changes in the hands of a skilled fish keeper will cause no greater harm to the BB in a closed system, than if one does only 5%. If I could, I would flush 100% of my tanks water daily.

edited to add - Philip beat me to the punch by seconds.

 

[koltsixx]

Again thanks to everyone RD. duanes cichlidfish for providing some great info. and personal views into the thread. And philipraposo1982 for creating the thread. I personally didn't realize how valuable this thread would be but it has been IMO a great learning experience. At very least I learned something and then some from a thread RD. linked me to regarding TDS.

And I'm sorry maybe I'm ridiculous but I was hoping to ask a question or two to expand my understanding.

1 If tap water is generally no risk to BB then is it okay to rinse/ clean media with untreated tap water?

2 If not then could a large water change be harmful to a tank that runs a Hamburg Matten Filter as it's only filtration? The original thread where this came up the tank in question ran only on a HMF. Which means the filter media would be in direct contact with the tap water before being treated as it flows through it as the tank fills?

 

[RD.]

Tap water is only safe when either: 1. it contains no disinfectant, or 2. the disinfectant that is present in the tap water is neutralized with a reducing agent before, or directly on contact when entering the aquarium.

This is one of the main reasons that I run my filters during my water changes, so that the water is constantly mixing & turning over while tap water is being introduced. It's also why one should always add water conditioner prior to filling, and not after. (or in intervals while filling) Both chlorine and chloramine are very toxic to fish, so either your tap water contains a negligible amount of disinfectant, or you best be neutralizing it as fast as possible before your fish swim through it. I have chloramine treated tap water, and a pH of 8.2, so ammonia toxicity is another thing that I have to factor into the equation. Not an issue if one is using the correct water conditioner, and the correct amount.

Having said all that, couldn't the water be treated prior to running through an HMF? As in a bit upstream - usually with HMF it is located on either one side of the tank or the other. Yes?

 

[duanes]

You'll notice in my response, I said "as long as reasonable precautions are taken".
I usually rinse biological media in old water change water.
This is because you don't always know (unless you test your tap water for chlorine/ chloramine) at what strength your water has been disinfected. There are times when water supply techs are faced with slugs of bad water entering the plant, and must react, by shocking the system to maintain human health. our fish at these times, can become collateral damage, if reasonable precautions are not practiced.
A slug of un-neutralized disinfectant on a majority of bacteria in biological filter media is a gamble, not worth taking.
I don' think the question is ridiculous, but I believe unproven theories by those who know nothing about bacteria, and taken as if true is ridiculous.
I also agree with RD, I run my sumps when doing water changes to mix, beside adding conditioner.
I match temps (using water from the water heater), and add temp adjusted water to the sump first, as opposed directly to the tank to reduce stress to the fish.
and practice regularly draining slimy water from the bottom of water heaters where chemicals/metals/sludge, can concentrate (there is a spigot there on most, water heaters) just for that purpose.
Its not there for aquarium people, but to maintain general efficiency of the water heating unit.

 

[RD.]

I on the other hand rinse my filter media in clean, treated, tap water, and always have. lol Even during times of turbid/dirty spring run off, when I know that residual disinfectant levels are going to run higher than normal in my taps. During those periods I simply add a bit more water conditioner than normal, and allow the bucket to sit for 30-60 seconds, then have at it. Never had an issue, been doing it this way forever.

But I would have to see this HMF set up before I can say more as to how that tank BB filtration system might be effected, or not.

 

[koltsixx]

Thanks again RD. and duanes Yes HMF's are usually placed on one side of the tank. And while I know the action of the conditioner is supposed to be instant I always wondered how fast before it gets mixed fully. In that thread the tank was 180 gallons with one inhabitant a juvenile aimara running a three month old HMF. The aimara had developed HITH and we where discussing possible actions to take. I was against 90% water changes as I had been told HMF filters take longer to establish then other filters. So I thought it might not be established and the water changes might prolong the process.

I personally run my filters during water changes as well but I do 35-50% channges every two-three days. And RD. you mentioned treating during the change, I personally have a habit where I change some while vacuuming the tank then add conditioner as I reverse the flow on my hose. I then repeat this around three times depending on the size of the tank.

Can I ask you guys what do you use to test your tap water? I just use an API master kit and obviously I should be using more tests if I want to know the levels you're talking about like chloramine, etc.