How can I convince someone that weekly 50% wc isn't dangerous?

isde02

Arapaima
MFK Member
Jan 4, 2011
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Im having a discussion with a lady that's convinced that 50% water changes will remove all of the food that beneficial bacteria thrives on and kill them off. Does anyone have a link or something I can tell her to convince her otherwise?
 

Evz jardini

Jardini
MFK Member
May 19, 2010
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Ask her what she thinks her filters full of ? What's the media for just to have pretty layers in it lol :D , sure there's plenty of threads on here about 50% w/cs you'll find something to convince her
 

bonesb66

Bronze Tier VIP
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Feb 1, 2010
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I don't think i've ever read a study of any sort on this - i think it's just been a general knowledge passed around by fish keepers?
Large volume water changes, to my knowledge, have been known to potentially damage BB colonies IF the chlorine/chloramine isn't removed?
I would therefore conclude that if the water is treated, let's say introduced from a HMA filter which removes the above and other heavy metals then i don't know of any logical reason as to why the BB could be harmed?
I've certainly conducted this level of water change, to one point i was doing a 210G 50% 3x a week - no mini cycles.
 

strollo22

Siamese Tiger
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May 21, 2012
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I regularly do 80% water changes with the filters on with no problem. You could probably just show her this thread. If she's really paranoid about it, tell her to turn her filters off when she does it so no new water can get into it.
 

808_fairladyz

Feeder Fish
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Feb 19, 2006
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If she's not comfirtable doing 50%, have her just do @ least 20% a week. I don't do water changes that big unless there's an emergency, but that's just my prefrence. 50% on my 430 gal aquarium would kill my water catchment system.:D

My Xbox gamer tag: xXclusive808x. Run & gun baby!
 

kzimmerman

Piranha
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Mar 18, 2009
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delmar md
I've had discussions with my brother in law about this issue, and it seems as though the chlorine level in the tap water is not high enough to actually cause a massive disturbance in BB levels, provided the water does not sit on them chlorinated, and comercial declorinators remove the chlorine fast. If the water contained enough chlorine to negatively impact the BB, wouldn't it be bad for us 2? The amount in chlorinated tap water is there to prevent the growth of these sorts of things in the water, not eradicate existing colonies. BTW, my brother in law is a wastewater treatment engineer. Lots of good discussions on bacteria and the denitrification cycle.
 

David R

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Apr 26, 2005
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50% could be dangerous, depending on the temperature, quality and parameters of the incoming water and the nature of the set up. How can you convince us it isn't dangerous without providing any sort of information?

50% on my tank would not only have me running out of water over summer, it would most likely lead to fluctuations in my tank water by removing half the already low mineral hardness that buffers the water against the large volume of driftwood. It would also take me about an hour to refill using the garden hose, and would at this time of year cause a fairly big drop in temperature if not pre-heated.
 

lando

Feeder Fish
MFK Member
Apr 3, 2013
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fort st john bc canada
This has always been a fun topic for me. I never do large water changes and my tanks are running great. Mind you I have very under stocked tanks with very good filtration.

140g running a fx5 an air stone and aqua clear 70 power head. Probably do 25-30% every 2 weeks. The fish are a 5" jag 3.5" red terror 3.5" yellow African. A 3" loach of some sort and a small red crab.

120g running 2 fluval 405 an air pump/ with air stone and a aqua clear 70 power head. 3 clown loaches around 2" 1 red devil 2" and a HBRTG around 6"

And I just sold my rhom but still iv always have some what large tanks with a small amount of fish and my ppm have never been an issue.

But I'm sure someone will tell me I'm doing it wrong!




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bonesb66

Bronze Tier VIP
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Feb 1, 2010
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50% could be dangerous, depending on the temperature, quality and parameters of the incoming water and the nature of the set up. How can you convince us it isn't dangerous without providing any sort of information?

50% on my tank would not only have me running out of water over summer, it would most likely lead to fluctuations in my tank water by removing half the already low mineral hardness that buffers the water against the large volume of driftwood. It would also take me about an hour to refill using the garden hose, and would at this time of year cause a fairly big drop in temperature if not pre-heated.
It would have to be pre-heated to even entertain the thought of 50% for me, as you say, fluctuations could make it dangerous however if you limit those by buffering the PH, removing the heavy metals, pre-heating and oxygenating then it's the same water going in as good as
 

skjl47

Goliath Tigerfish
MFK Member
May 16, 2011
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Tennessee
Hello; Here is a link to an article about cycling and the bacteria. A portion mentions that the bacteria cling tightly to surfaces. Apparently little of the bacteria will be in the water.

http://www.americanaquariumproducts.com/nitrogen_cycle.html

I tend to agree with the comments of others in that 50% each week can have issues to overcome. I also do not see the need for such a large percentage of water change so often unless the tank is very overstocked or there are some other issues such as overfeeding. If you are determined to get the friend to such a water change schedule, perhaps that level can be approached gradually. Say 10% first, then 15% and so on with the percentage increments increasing. This may help avoid the dramatic change in water conditions that a sudden increase to 50% could cause. A plan for dealing with the temperature differences and other issues involved with such water changes might be good practice.

Bear in mind the consequence of talking someone into doing something they apparently do not want to do. Should things go wrong will you be willing to stand up and make it right?
 
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