Help! First Salt Water Change And Killed 2 Fish

Kevin F
  • #1

Thanks for taking the time to read this post.  Here is what's happening...

I just set up a 24 gallon tank (nano cube) and have had a high sucess rate until my 1st Water change last night.  I came back to find 3 of my peices dead (Yellow Tang, Clown Trigger, Boxer Shirmp) and the ones left are pretty stressed out. It has been about a month and a half since I started my minI reef and as recommended I changed out 20-25% of the water and replaced it with salt water from my local fish store. I did my best to take the necessary precautions. Matching the water temperature (80º), rinsing the filter out with disposed water from the tank, added the new water slowly (though I probably could have done it slower), added live nitrifying bacteria and oxy-boost.   

Does any one out there know what could be a possibly cause for this and what I should try to avoid in the future?

Obviously, I am not going to be getting my salt water from that store anymore. That's for sure.  But if you could let me know if there are any tricks to water changes.  How often? How much water? Anything at this point would help.  My goal is to have a nice little minI reef.  I hope!

Here is what I currently have in my 24 gallon tank.

10lbs. live rock
1 clown fish
1 damsel
1 serpent star fish ( who has oddly climbed to the very top of the tank, trying to get close to the filtration intake)
3 Snails ( nothing fancy)
1 rock crab

Like I said, I would appreciate any help I can get with this.  The thought of killing these little guys isn't a fun one and I want to do everything I can in the future to avoid it.

Thanks so much.
  • #2
HI Kevin,

First - Do you have a hydrometer (for specific gravity) and test kits for ammonia, nitrite, nitrate, alkalinity and high level pH? If not, you'll need them to monitor the nitrogen cycle that has to complete in all new setups. If the cycle hasn't completed then you will most likely lose some fish from stress or disease. Also, depending on the shape your live rock was in when you got it, it can take anywhere from 1 - 8 weeks for the hitch hikers to die off. During that time, the dead or dying organisms in the live rock are releasing ammonia into your system, which is highly toxic to your fish. I'm not sure about using the nitrifying bacteria and oxy-boost because I've never used them.

Did you test the pH and specific gravity of the store bought water? You wouldn't think so, but these levels could have been significantly different from the levels in your tank. I would recommend mixing your own salt water to save on costs.

For the water changes I like to do more frequent small changes instead of less frequent large changes. Usually, I try to change about 10% of the water every week or so in my saltwater tanks.

Also, the yellow tang (about 8 inches adult size) and the trigger (about 10 inches adult size) are going to grow way to big for your 24 gallon. For better long term success, I would also try to get about 10 more pounds or live rock for your tank. Side note - I find the stuff growing on the rock just as fascinating as the fish.

More info:

Hope this helps and good luck,
Kevin F
  • Thread Starter
  • #3
Hey Mike,

Boy do I appreciate your help with this.  Thanks so much for the tips.

To answer some of your question.  Yes I do have a hydrometer and had tested the water in the tank before the water change.  It was fine and right in safe range.  I didn't test the actual new water but tested it after the water change was complete and was still in good shape.  From now on I will definitely test the water before it goes in my tank.  I think doing smaller water changes is definitely the way to go.  Would you recommend and certain type of Salt Mix to get?

In terms of test kits.  The test kit I picked up only test for pH, Nitrite, and ammonia levels.  So far all levels look good but the pH is a little questionable.  I am consistently at  7.7.  I have read I should be closer to the 8.0 - 8.3 range.  Is there a way I can boost my pH levels?

I will go pick up a kit to test the alkalinity and nitrate.  Are the specific levels I am aiming for in your opinion?

Now when it comes to fish... The yellow tang and Trigger really grow to that size?  Wow.  I wasn't aware of that.. Your right that won't be to good in the long run.   Thanks for the heads up.

10 more pounds of live rock sounds like a good idea.  I too, like the stuff growing on the rocks.  Especially if I can find some hardy corals down the road. 

Once again, thanks very much for your help with this.  You got one great website here!  Keep up the good work.

  • #4
Try to increase the pH level. Buy some salt mix and do a couple of small (10%) water changes every 3 days or so until the pH is reading in the 8.0 - 8.3 range. For your 24 gallon you can use a new, clean 5 gallon bucket for getting the saltwater ready. When mixing the salt, first add some dechlorinator/dechloraminator, add the salt according to the directions, pop in an airstone (hooked up to a small air pump) and let it aerate for 2 or 3 days. As far as salt mixes go, I like coralife and instant ocean. There are a ton of opinions out there as to which is the best. The two mixes mentioned prior work for me and I usually get whichever one is cheaper at the pet store. Here is a link comparing some of the most popular mixes available: .

Levels you want:
specific gravity: 1.020 - 1.024
Ammonia - 0 ppm
Nitrite - 0 ppm
Nitrate - 20 ppm or less
pH - between 8.0 - 8.3
Carbonate Hardness - 7 - 10 dkh OR Alkalinity - 2.5 - 3.5 meq/L (these are different measurements of mainly the same thing)

I'm guessing here, but I would think that your carbonate hardness (alkalinity) level may be low, thereby causing your pH to drop. A low carbonate hardness reading means that the water has low buffering capacity and is followed by dropping pH levels. You want to keep the carbonate hardness levels up to prevent this. Partial water changes should keep these levels where they need to be. It's been my experience that frequent small water changes are your best friend in this hobby.

Let us know how it goes
Kevin F
  • Thread Starter
  • #5

How you keep up and answer all these questions, I will never know. I hope your well paid my friend.

Thanks for the advice and the level ranges you provided for me. That helps greatly.

I went ahead an bought a Superbuffer to get my pH levels back up to a good range. I started adding it in today and will continue until I am in a good range. I also got an alkalitity testing kit to better monitor those levels as I am doing this.

Wanted to also let you know that adding another 10lbs or live rock was a great suggestion.... Picked up some this morning and my tank is looking sharp. I just can't wait to start adding some corals down the road.

Thanks again.
  • #6
Well, I have a tropical freshwater tank and it seems to me that with every partial water change, there's gotta be one or 2 that don't make it. What does one do?!?! I am getting frustrated, as well. All my levels are, I'm clueless. *sigh* ???
Miss Mouse
  • #7
Hey guys, about all these water changes - I only do mine once every 3 or 4 months - I know that sounds quite bad but I found it stressed my fish out and quite a few got ill or died after water changes and I reckon maybe it just isn't as necessary as you think? I think if you have an overstocked tank full of fish and nothing to clean all the bad stuff out then you'll have to do all the changes but if you keep the numbers down and avoid too much food floating around then your water will stay clean.
I'm in England so the water may differ here so take that into account...
Kevin F
  • Thread Starter
  • #8
Hey Miss Mouse

Do you have a Saltwater tank or freshwater? And how many gallons is it?

Miss Mouse
  • #9
HI Kevin,
I have
*45 US gallon cold freshwater (currently has 4 goldfish but is going tropical when they go into the new pond)
*10 US gallon cold freshwater (2 goldfish, 1 moor,3 white cloud minnows and 2 black tetras)
*6 US gallon with 4 platys
*6 US gallon with a dwarf gourami, an otocinclus and a small pleco (he's moving into the 45 gallon when the goldfish go)
*8 UK gallon tropical bi-orb

Whew... hard time remembering all those. :
Kevin F
  • Thread Starter
  • #10
Wow!! That's quite a few tanks you have got going there. No wonder you are only changing the water out every few months. That's a lot of work! My salt water tank is only 24 gallons which seems to be a pretty good size for me so far. Not to small and not to big. I just have to control myself from buying any more cool fisheys! : It's pretty rough when you have a minI reef cause there are so many cool options. But your right, it pretty darn expensive. Worth it in my book. I would definitely look into it once your out on your own.

Take care,

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