Let's Set The Record Straight About Pwcs

[NeonBlueLeon]

So I am in the process of desalinizing a tank after an Ich outbreak.  I've devised a plan to gradually decrease the salinity down to below 1 tbps total via 10 - 40% PWCs.
 
I guess the unanswerable question is this:  is there such thing as too many PWCs?  Namely, will too many PWCs affect the bio-filter?  A few things to consider:
1)  Are the temperatures of the tank water and new water matching?
2) Are the pH and hardness of the water matching?
 
In my case, I will be monitoring temperature, pH, and hardness before adding new water.  So with that being said, will too many PWCs affect the bio-filter?
 
I ask this because I have done five PWCs within the last two days.  I have done 10%, 10%, 10%, 20%, and 20% PWCs.  I have also observed a very small mini-cylce in the tank, but I am suspecting the cause to be one of my blades browning.  I have removed the offending plant from the tank.

 

[Chad]

A reef keeper I know did an experiment where he did a small water change each day rather than his normal large one. He found that it was beneficial.
 
http/www.thereeftank.com/forums/f6/daily-water-change-experiment-179577.html

 

[Mamashack]

Sounds interesting! Is that likely to be beneficial to FW tanks too or or would it only benefit reef tanks?

 

[daizeUK]

I suspect your mini-cycle is not due to the water changes.  The bacteria mainly live in a biofilm in the filter and on the substrate or other surfaces in the tank, changing the water does not affect them as they like to cling and not float around.  Stirring up the substrate can disturb them a bit though.

 

[eaglesaquarium]

So I am in the process of desalinizing a tank after an Ich outbreak.  I've devised a plan to gradually decrease the salinity down to below 1 tbps total via 10 - 40% PWCs.
 
I guess the unanswerable question is this:  is there such thing as too many PWCs?  Namely, will too many PWCs affect the bio-filter?  A few things to consider:
1)  Are the temperatures of the tank water and new water matching?
2) Are the pH and hardness of the water matching?
 
In my case, I will be monitoring temperature, pH, and hardness before adding new water.  So with that being said, will too many PWCs affect the bio-filter?
 
I ask this because I have done five PWCs within the last two days.  I have done 10%, 10%, 10%, 20%, and 20% PWCs.  I have also observed a very small mini-cylce in the tank, but I am suspecting the cause to be one of my blades browning.  I have removed the offending plant from the tank.

 
Let me put it this way:  Where do the fish live?  In a river and the water is constantly changing.  So, is it possible to do too many water changes?  I doubt it.

 

[CezzaXV]

I wouldn't have thought it was possible to do too many changes as long as the water is dechlorinated and reasonably temperature matched. Back before I went marine, I used to do 80% water changes every week. The water wasn't always as temp matched as I'd have liked it and I poured dechlor into the tank and hosepiped the new water direct to the tank. Never had any problems.

That said, I did shut off the filter before doing this.

I would have thought if anything, your mini cycle would be due to the increased salinity and (I presume) temperature.

 

[Chad]

What water changes alter isn't so much the bacteria (they do that a little) but the pH and trace element content of the water.

 

[NeonBlueLeon]

Thanks for the help everyone.  This has always stumped me a bit when it came to frequent water changes.  I know as long as the temperature and pH are the same, the fish won't suffer from frequent PWCs.  My main concern was just the bio-filter.
 
Anyway, thanks for all the feedback.  I really appreciate it!  Happy fish-keeping!

 

[zain611]

The beneficial bacteria cling tietly on the filter sponges and some would be on the ornaments or substrates so i cand see water changes can affect the bacteria