Cloudy Tank

[Miss Wiggle]

I would advise against doing 100% water changes since these will harm the beneficial bacteria in the tanks filter

So long as the filter media are kept damp and the new water is the same temperature and pH as the old water, how will it affect the beneficial bacteria which are cultured to live in the filter media?

DO NOT EVER DO 100% WATER CHANGES!!
10% weekly is the most you should in normal conditions.

Really? Damn, I better go tell Skifletch he is an irresponsible reef-keeper for advocating 100% changes. And that Tolak, despite breeding many hundreds (thousands) of angelfish he regularly changes 50-80% of fish, maybe I should advise him he is doing it wrong. And bignose, he says 100% can be done. Pretty sure CFC needs to be corrected on this too.

Orrr, maybe, just maybe, 10% is an arbitrary amount you have fixed on which is roughly 10% of the maximum that can be done (as in, 100%). So long as th pH and temperature of the new water is the same as the old, you can change as much as you want. Obviously one has to be careful to keep filter media wet and place the fish elsewhere, but 100% is very do-able without major issues.

my thoughts exactly, in fact we changed our tank around yesterday and did a 100% water change, everyones fine and dandy this morning.


the bacteria we cultivate do not live free swimming in the water, they attach to surfaces (this is why filter media is designed to have the maxiumum surface area possible) so removing all the water will not be a problem. Although it's worth noting that you will never actually do a 100% water change, it's 99.999999% because the filter media needs to be kept wet, so you retain some water there by not completely drying out the media. But yeah, it's absolutley fine to take out all the water if needs be, just stick the fish in a bucket or something, drain the tank, refill it, when it's up to temp add the fish back in.

Keeping the pH stable doesn't even matter that much for most fish.

 

[Tokis-Phoenix]

I would advise against doing 100% water changes since these will harm the beneficial bacteria in the tanks filter

So long as the filter media are kept damp and the new water is the same temperature and pH as the old water, how will it affect the beneficial bacteria which are cultured to live in the filter media?

DO NOT EVER DO 100% WATER CHANGES!!
10% weekly is the most you should in normal conditions.

Really? Damn, I better go tell Skifletch he is an irresponsible reef-keeper for advocating 100% changes. And that Tolak, despite breeding many hundreds (thousands) of angelfish he regularly changes 50-80% of fish, maybe I should advise him he is doing it wrong. And bignose, he says 100% can be done. Pretty sure CFC needs to be corrected on this too.

Orrr, maybe, just maybe, 10% is an arbitrary amount you have fixed on which is roughly 10% of the maximum that can be done (as in, 100%). So long as th pH and temperature of the new water is the same as the old, you can change as much as you want. Obviously one has to be careful to keep filter media wet and place the fish elsewhere, but 100% is very do-able without major issues.

my thoughts exactly, in fact we changed our tank around yesterday and did a 100% water change, everyones fine and dandy this morning.


the bacteria we cultivate do not live free swimming in the water, they attach to surfaces (this is why filter media is designed to have the maxiumum surface area possible) so removing all the water will not be a problem. Although it's worth noting that you will never actually do a 100% water change, it's 99.999999% because the filter media needs to be kept wet, so you retain some water there by not completely drying out the media. But yeah, it's absolutley fine to take out all the water if needs be, just stick the fish in a bucket or something, drain the tank, refill it, when it's up to temp add the fish back in.

Keeping the pH stable doesn't even matter that much for most fish.

The reason why i advise against 100% water changes is because i have known many people who have done this and accidentally caused their tank to mini cycle- i know full well that the beneficial bacteria lives in the filter etc, however i am sure doing a 100% water change must be stressful to the beneficial bacteria in some way because of the amount of people who's tanks have mini cycled after doing such colossal water changes.
I only advise what i know to be 100% safe, and concerning 100% water changes i see some doubt over their benefit.

 

[Miss Wiggle]

thing is speaking purely theoretically and scientifically we can all see that 100% water changes should be perfectly safe and not damage the bacteria. But as we know fishkeeping is not black and white, the variables in tank set up's mean that sometimes tank's do not behave how we expect them too, as such we can all only go on the basis of our personal experiences as a supplement to established science.

I've done 100% water changes on many occasions and never experienced a problem, likewise I know several people who say the same.

Thing is, when people do a 100% water change, they're often doing a big tank clean out at the same time. So they may remove a large volume of plants (which of course take up ammonia, pruning too heavily can cause a mini cycle) or do a really heavy gravel vac or even change the substrate (stirring up all the debris can cause a mini cycle) which will contribute to the circumstances. Obviously this isn't the case every single time, but in a few cases it will account for it.

 

[waterdrop]

Yes, I agree with this last paragraph that MW writes. Both ideas make sense about mini-cycles.

The "degree of cleaning" thing is particularly interesting in that it could possibly have a bit of a double effect in theory. When organic debris is stirred up from deep in the gravel, it is exposed such that the heterotrophic bacteria can now have a go at it and quickly reduce it to ammonia. At the same time, some of the good autotrophs may be swept out, a small amount of them, because they may have been attached to some of the larger debris that is siphoned out.

We've all experienced huge differences in a given tank cleaning. Sometimes the tank is still relatively clean, other times we might have let it go longer than usual or have had some plant die-offs or something - so it varies a lot.

~~waterdrop~~

 

[Miss Wiggle]

aye, another one is if the tank is overstocked/underfiltered, if that is the case then bacteria will be living wherever they can, this will include being in the substrate, on the decor and debris, if you remove any of this you can then start a mini cycle.

general point is that a 100% water change in itself cannot possibly harm a tank, nothing that you remove has bacteria in, nothing that you add has capacity to harm the bacteria, it's all the supplementary things that go with water changes, all the other things you may be doing at the time which could potentially have an effect.

 

[Tokis-Phoenix]

aye, another one is if the tank is overstocked/underfiltered, if that is the case then bacteria will be living wherever they can, this will include being in the substrate, on the decor and debris, if you remove any of this you can then start a mini cycle.

general point is that a 100% water change in itself cannot possibly harm a tank, nothing that you remove has bacteria in, nothing that you add has capacity to harm the bacteria, it's all the supplementary things that go with water changes, all the other things you may be doing at the time which could potentially have an effect.

This probably explains why the other people i knew got mini cycles when they did 100% water changes- however technicalities aside, considering that it seems there are numerous things that can be upset during 100% water change, i still don't think they're that advisable. Personally i think 30-60% water changes are the best, whether on a once weekly basis or for more regular practice etc, i never heard anyone of upsetting their tanks through water changes of this size .