Safe Number Of Water Changes?

[Mushroom]

I have a 67L Jewel tank, that currently has 3 x cory's, 2 x glassfish, 2 x danio's and 2 x adult bristlenose plecos that have spawned 2 sets of eggs.

The problem is that I have now about 60/70 bristlenose babies in the tank. This was accidential, I had no plans to breed and I was sold 2 females, but one he turned out to be a she and by the time I knew it was too late. I know this is far too many fish for one tank, but unfortunately I don't currently have the means to house another tank. I am in the process of getting them homed in a LFS, but they can only take so many at the time, I don't trust the other store as I gave them 10 fish already and all but 1 died. I am homing another 15 tomorrow.

Anyway, the tank gets very dirty, I have been using the gravel cleaner once a week now, but the water is still quite bad even though I cleaned it yesterday, doing a 33% water change. How many water changes can I do without badly affecting the equilibrium in the tank? I was tempted to give it another 33% change today again, but thought I would leave it until I got further advice.

Can't wait until they are homed, I need to get more glassfish but can't risk it just now.

 

[Aphotic Phoenix]

You can do multiple water changes a day without ill effect unless you've been doing something to chemically alter the pH of the tank.

 

[rdd1952]

You can safely do a water change every day. Some people who breed discus do them more than once a day. I had issues with green water on a 75 gallon tank a couple years ago and did 50% water changes every day for 2 to 3 weeks to try to clear he problem and the fish were fine. The key is that the temp and pH aren't changed too much but that should be an issue.

 

[backtotropical]

Water changes are not an exact science. The key point to remember is that you are changing the water to remove things which are toxic to the fish (ammonia, nitrite, nitrate etc), however if you change the water parameters too quickly, the fish can suffer from osmotic shock which can kill them also. It's important to try to keep a balance between the two. Toxins must be removed but do it too quickly and you'll kill the poor little guys anyway.

What are your parameters? (ammonia, nitrite, nitrate, PH)

If ammonia is sky high, i would say big water changes are the best option, if it is nitrate which is high, i would try to do it more slowly.

Hope this helps.

 

[Aphotic Phoenix]

however if you change the water parameters too quickly, the fish can suffer from osmotic shock which can kill them also

Generally not something you should have to worry about if you always use the same water source, and have been doing regular maint in the first place.

 

[backtotropical]

however if you change the water parameters too quickly, the fish can suffer from osmotic shock which can kill them also

Generally not something you should have to worry about if you always use the same water source, and have been doing regular maint in the first place.

I agree. However, should those criteria not be met for whatever reason and you find yourself in a position where your water parameters have changed dramatically, particularly PH, it certainly is something you should consider. You only need to look at the 'emergencies' section to see how many people it may apply to.

 

[Bignose]

however if you change the water parameters too quickly, the fish can suffer from osmotic shock which can kill them also

Generally not something you should have to worry about if you always use the same water source, and have been doing regular maint in the first place.

I agree. However, should those criteria not be met for whatever reason and you find yourself in a position where your water parameters have changed dramatically, particularly PH, it certainly is something you should consider. You only need to look at the 'emergencies' section to see how many people it may apply to.

Yes, but the term pH shock is overused and little understood. Fish in the the wild are exposed to very quick changes in pH all the time, and there aren't mass killoffs. During the day, as the sun comes out, warms up the water, plant activity changes, lakes and ponds pH can change as much as 2 units. When there are quick, fast rains, a la monsoon season for example, the runoff is usually of a very different pH than the bodies of water. The fish don't die from that either. pH is blamed for a lot that it doesn't do. It has been cited a lot in the scientific literature that a fish can adapt it's internal pH to match the ambient conditions in about an hour.

There are few times not to do too many water changes. If the tank is older, hasn't had a water change in a long time (or ever) and there is ammonia present and the tank has a very low pH. In this case, the high acidity has shifted the balance of ammonia-ammonium to ammonium, which is much less toxic. If you put in new water too quickly, the pH will raise, and some of the ammonium will convert back to the much more toxic ammonia.

The other time is if you are still running an undergravel filter and you root around in the gravel every time you do a change. You could be sucking up bacteria then, or at the very least disturbing when the bacteria has colonized meaing that the currents though the gravel bed may not be running next to the bacteria anymore. But, almost no one runs an undergravel ffilter as their primary and only filter anymore.

Otherwise, you can really do very large water changes pretty much as frequently as you want. Getting the water parameters close to one another is good, I think that temperature jumps or hardness jumps are more stressful that pH jumps, but so long as you are using the same water source (as said above) it really shouldn't be an issue.

 

[backtotropical]

however if you change the water parameters too quickly, the fish can suffer from osmotic shock which can kill them also

Generally not something you should have to worry about if you always use the same water source, and have been doing regular maint in the first place.

I agree. However, should those criteria not be met for whatever reason and you find yourself in a position where your water parameters have changed dramatically, particularly PH, it certainly is something you should consider. You only need to look at the 'emergencies' section to see how many people it may apply to.

Yes, but the term pH shock is overused and little understood. Fish in the the wild are exposed to very quick changes in pH all the time, and there aren't mass killoffs. During the day, as the sun comes out, warms up the water, plant activity changes, lakes and ponds pH can change as much as 2 units. When there are quick, fast rains, a la monsoon season for example, the runoff is usually of a very different pH than the bodies of water. The fish don't die from that either. pH is blamed for a lot that it doesn't do. It has been cited a lot in the scientific literature that a fish can adapt it's internal pH to match the ambient conditions in about an hour.

There are few times not to do too many water changes. If the tank is older, hasn't had a water change in a long time (or ever) and there is ammonia present and the tank has a very low pH. In this case, the high acidity has shifted the balance of ammonia-ammonium to ammonium, which is much less toxic. If you put in new water too quickly, the pH will raise, and some of the ammonium will convert back to the much more toxic ammonia.

The other time is if you are still running an undergravel filter and you root around in the gravel every time you do a change. You could be sucking up bacteria then, or at the very least disturbing when the bacteria has colonized meaing that the currents though the gravel bed may not be running next to the bacteria anymore. But, almost no one runs an undergravel ffilter as their primary and only filter anymore.

Otherwise, you can really do very large water changes pretty much as frequently as you want. Getting the water parameters close to one another is good, I think that temperature jumps or hardness jumps are more stressful that pH jumps, but so long as you are using the same water source (as said above) it really shouldn't be an issue.

I'm no scientist. I'll have to leave you to argue that one out with Mr Axelrod.

 

[Mushroom]

Thanks for all of this info, it has been very helpful and informative, I have printed it out for future reference.

I'm going to buy myself a testing kit today for the water. This may sound bad, but I haven't had one of these for a long time, I usually stick to the same types of fish that I understand (boring I know) but as a result I very rarely lose fish and haven't had any sickness in the tank for years so didn't bother with testing. All of my fish, except the bristlenoses are years old. The tank itself about 6 years old. I stick to a regular routine and guessed I must be doing something right if the fish were happy enough so got out of the way of testing.

I always use the same water source, and will invest in a testing kit today to see what the levels are. I don't have an undergravel filter, it is the Jewel internal filter that is on the wall of the tank so no worries about the bacteria being sucked up.

I'll do some testing, change some water and test again. I got worried as I lost a clown loach, I have found them the first to go though in bad water conditions.

I have learnt my lesson as far as the idiots in the LFS tell me, they really haven't a clue and will say anything to get a sale. If it wasn't for them I wouldn't be in this situation. Ah well, I suppose you live and learn. It was nice to see the fish hatching and growing though, but once is enough for me! Unfortunately I'm far too busy to spend the time I would like to on my tank.

I couldn't believe what the idiot in the LFS said to me - "just flush them down the toilet"!!!?? I nearly choked. It's the last time I will be shopping in there.

Thanks again!

 

[vinylman]

I couldn't believe what the idiot in the LFS said to me - "just flush them down the toilet"!!!?? I nearly choked. It's the last time I will be shopping in there.

Thanks again!

Sadly, that probably won't be the last time you hear something that stupid in a LFS. As has been said daily water changes aren't a problem. It's worth noticing the fishes behaviour when you do it, though. It can stress some fish out big time; if it does, just do it every other day. Fry really need the cleanest water possible. Do you have anything you could use as a temporary home for them?. That way you could change their water every day.

 

[rdd1952]

I couldn't believe what the idiot in the LFS said to me - "just flush them down the toilet"!!!?? I nearly choked. It's the last time I will be shopping in there.

Thanks again!

Sadly, that probably won't be the last time you hear something that stupid in a LFS. As has been said daily water changes aren't a problem. It's worth noticing the fishes behaviour when you do it, though. It can stress some fish out big time; if it does, just do it every other day. Fry really need the cleanest water possible. Do you have anything you could use as a temporary home for them?. That way you could change their water every day.

Also, if you notice the fish being stressed by the WCs, try doing them when the lights are off since you aren't really doing maintenance and gravel vacs but just changing water. If you are doing them when the lights are on, you can cut them off when you finish to ease the stress as I think the lights in general stress fish.

 

[ArauraDiscus]

You can do 5 water changes a day If you like. You can never do too many.

 

[backtotropical]

As you will see, not everyone always agrees but that is the nature of the beast.

Hope all the info helped.

 

[andywg]

I'm no scientist. I'll have to leave you to argue that one out with Mr Axelrod.

Does Mr Axelrod explain how a fish can experience osmotic shock when new water with identical (or near identical) pH and hardness levels is introduced?

I bet he doesn't

So long as the tap water is very similar to the water being changed (which in a tank with frequent weekly water changes it will be - barring human intervention to adjust parameters) then there is no issue with water changes.

Lots of people are setting up auto constant changers that change up to 100% of the tank water each day by putting new water in and having the existing overflow into a drain.

Osmotic shock is going to be a problem changing hard water into a soft water tank, or when dealing with brackish and marine tanks where the salinity level is an added parameter to match.

 

[Bignose]

As you will see, not everyone always agrees but that is the nature of the beast.

Hope all the info helped.

Forgive me if this sounds belligerent, because it is not how I take it to be meant (it is tough to express tone over the written word), but the scientific literature is quite clear on this point. It is a well-researched fact... there is no agree or disagree. Reality doesn't change based on what one agrees or disagrees with. And, reality is that fish can experience very large, very sudden changes in pH without suffering ill-effect like deaths. Again, consider the washoff during a fast, hard rain. Rain water's pH is normally many pH units different from bodies of water, and there isn't a massive fish die off every time there is a hard rain. Quite frankly, fish as an animal wouldn't have lasted too long if every time it rained hard the bodies of water would become fish-free.

You already said that you aren't well-versed in the science, so I won't go to the trouble of citing the specific studies, nor the biological mechanisms available to the fish to deal with pH changes. But, take it from someone who has read them, pH shock is not anywhere near the problem the Internet has made it out to be. Differences in hardness and mineral content are far more difficult for fish to handle. (I can try to explain that if you want, too, but it is fairly technical. I am happy to try, if you ask, however.)

Finally, and again, this is not trying to put you down, but just because a website, or in this case a lot of websites, say something, doesn't necessarily mean it is true.