Fish are dieing after water changes

timmycat

Gambusia
MFK Member
Dec 23, 2009
134
6
18
frankfort Il
Every time I do a water change I loose a fish. It seems like only barbs, id sharks, and bala sharks can't handle the water. All my other fish do just fine I have an ro system with all brand new filters in it. But I'm still losing fish after water changes. Any suggestions?
 

tarheel96

Polypterus
MFK Member
Feb 2, 2015
457
311
87
North Carolina
About 1/3 - 1/2 of people is the US have chloramines in their water. Chloramines are formed when ammonia is added to chlorine. It is a weaker disinfectant than chlorine (only) but remains in the water for a very long time. If you have chloramines then your tap water will test positive for ammonia.

Note: Test kits measure Total Ammonia (Ammonia + Ammonium). Seachem alert is one kit which measures toxic ammonia (NH3) only.

I would test your tap water for ammonia as suggested above. But ammonia toxicity depends on pH and, to a lesser extent, temperature. For example,

at pH 7.0, with 3.0 ppm Total Ammonia (NH3 + NH4), there is 0.0173 ppm ammonia (NH3)
at pH 8.2, with only 0.21 ppm Total Ammonia (NH3 + NH4), there is 0.0177 ppm ammonia (NH3)

It takes 14 times the level of Total Ammonia at pH 7.0 to reach the same toxicity of that at pH 8.2. This assumes a temperature of 77 degrees.

So I'd definitely test the pH from the tap along with ammonia if you believe ammonia toxicity could be the cause.

The most probable cause is osmotic shock (change in TDS). This is the result of water changes being performed infrequently. Some fish are more tolerant than others to that.

Another possibility: what are you doing to the RO water? I assume you're adding something to it, right?
 
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