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Re: [APD] Massive Fish Kill


If I'm reading this right, after a 50% water change pH test showed your *aquarium* water off the charts low, but your *tap* water off the charts high.

If this is the case, then it is possible you had a massive CO2 dump overnight. Portland water (AKA liquid silk) has a very low KH. KH is a measure of how much carbonate buffering capacity the water has. The buffering keeps the pH from swinging wildly when CO2 is added. Here's the scenario I am guessing:

You did the initial water change on Sunday night. You noticed a CO2 surge but were unconcerned. Overnight on Sunday the CO2 continued to surge. Since the KH of Portland water is low (usually 1-2 degrees), there was nothing to keep the pH from dropping fast and hard, which would kill your fish (a small change, or slow change, is generally considered harmless).

Then you did a 50% water change, which would have raised the pH by dropping the CO2 level, both because the tap water had less CO2 than the supercharged tank water, and because the agitation of draining & refilling the tank would allow the CO2 to outgas. This may be why your CO2 test showed tolerable levels, or it may be that CO2 tests are not very accurate, as Scott H. said. 

Then, you added CACO3, calcium carbonate, which raises both KH and GH. The carbonate part of the CaCO3 buffered the effect of the acid (dissolved CO2) in the water, raising your tank water pH to 6.5. (I'm assuming it's a typo where you said adding CaCO3 brought the pH down, since you'd earlier said your tank water was off the charts low).

My suggestion for you is to get a KH kit. Now. Don't mess with adding CO2 to Portland water without one - it is just to risky, as you may have found out. For your 45 gallon tank, 1.5 teaspoons of CaCO3 should raise your KH to 4 or 5, but you should test that for yourself.

If I misunderstood about the tank & tap water readings, I apologize for this useless post.

Rachel from Forest Grove, OR, about 20 miles west of Portland with the same way-soft water.

----- Original Message ----- 
  From: John Van Rees<mailto:revjohn at spiritone_com> 
  To: aquatic-plants at actwin_com<mailto:aquatic-plants at actwin_com> 
  Sent: Tuesday, April 13, 2004 9:39 AM
  Subject: [APD] Massive Fish Kill

  Ok... I had an expensive learning lessen Monday morning.. and would like
  input so it doesn't happen again.

  Sunday we did a 30% water change on a 45 gallon planted tank. I added  a
  couple of caps of fluorish iron and Fluorish. This may have been foolish...
  but I thought it was way look on ferts so didn't even think about it.being
  stupid. I didn't do any tests on the water as everything was looking healthy
  with no problems.. fish and plants. I added co2 through a DYI.  There was a
  surge of CO2 as I lowered the water level but this has not caused a problem
  in the past so I wasn't concerned.

  Monday morning I woke up to 95% dead fish.... 3 Altums, 3 Clown Loaches, 5
  Rainbow fish, 5 cardinals, 2 SAE's. ACK!!!!!!

  I immediatly pulled out water to test.... and then did a 50% water change.
  After the water change I tested the water I pulled out before the water
  change. The PH was off the chart (for the low range) of my Aquarium
  Pharmaceuticals Kit.  Ammonia was 0, Nitrites was 0. I then tested tap
  water... off the charts as well. (not usual for Portland Oregon water!).
  After water change I thought to test to see what the levels for CO2 were and
  Iron to see if I poisened the fish from not being careful with the ferts.
  Iron was .01 and Co2 was 8 ( I think I remember that right) tested with a
  Red Sea test kit. So.. even with a 50% water change of the Iron and Co2 was
  doubled it wouldn't be enough to cause the kill, or would it?

  I again tested the PH after the 50% water change and it was still of the
  charts...so I added 1 TSP of calcium carbinate to bring it down.. which it
  did to 6.5.

  I can only figure that the tap water was such a high PH that it caused a
  huge ph swing and that is the culprit.

  The remaining fish... one pair of Rainbows, on Honey Gourmami and 5
  cardinals are looking great.

  Any input or advice is welcome.. but please no demeaning remarks.... I have
  all ready done that to myself.


  John Van Rees

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