Water changes?

[Skiploder]

They can but more due to the sudden temperature change than anything. Plus you have to consider the PH. Some decorations will buffer the PH over time. Like driftwood or coral. If you then do a huge water change, the PH will be different and that can throw them into shock as well. Tap water can be tricky. Mine is well water and is VERY hard. I cant get the water stats correct no matter what I do so I just use bottled water for every change now. If you have city water it will be more stable and better for water changes.

Another thing is some people think they should clean all the gravel and filters with every water change.. Thats a no no. If you do that, you remove all the good bacteria. In essence you will begin to "cycle" the water every time you do a water change. The cycle is the initial amount of time it takes for the nitrites to turn into nitrates from building a healthy amount of good bacteria. If there is any amount of nitrItes in the water, it will kill the fish or shock them so bad they may not recover.

So alternate water changes, gravel cleaning and filter cleaning, leaving at least a couple weeks in between each one. Gotta keep the good bacteria in there to keep the tank healthy.

pH shock?

I thought it had been proven that fish can survive a rapid ph shift and that the causative agent was rapid differences if TDS.

http://www.mtfb.com/MTFBJUNE/MTFB2%2...bsarticle2.htm

A sudden change either way causes osmotic shock.

I used to swap apistogramma panduro with a breeder from Shasta County. His ph was slightly hard (7.8) but his TDS levels were actually low. My ph was barely above 6.0 and my TDS levels were low in my planted tank due to peat being run in the filter. Never lost a fish.

I shipped some apistos to a guy in Nevada who dip tested the pH in the bags and found that his planted CO2 tank's ph was equal to the water in the bags. He dropped the fish in and lost 3 out of 5 almost immediately to "shock". The remaining two went into shock and eventually recovered.

He phoned me and explained the problem. I shipped my fish with instructions on acclimated - stressing the need for a TDS test. He ordered one from Dr. Foster's Smith.

6 days later he calls and tells me he got the meter and tested his water which came in over ppm. I tested mine and it came in around a buck fifty. That change is what killed his fish.

A number of years ago I worked on the new construction of a local aquarium and got to talk at length one afternoon with the person in charge of the fresh water exhibits. She told me point blank that there is no such thing as pH shock and that when acclimating new arrivals they shot for a 15 to 25 ppm window for TDS and no more than a 2 degree temperature change.