Ph Swing / Glo Fish Dying Daily From Alkaline Buffer

[halladurg]

Let me start off with a little background...
 
I had 9 glofish (danio), some corys, a bolivian and a blue ram in my 20gal long tank.
I have had my glofish and corys since January (8 months) and have never had one die. They went through 3 tank changes and were my starter fish, so these were extremely hardy fish. I've had my rams for about 2 months.
 
It had been about 2 months since my last filter change, so last weekend I replaced the filter and did about a 33% water change. I keep my pH at 7. When I replaced the water, I put way too much acid buffer in and didn't test it. Well the next day my bolivian ram started looking very sick and I panicked. I went to the LFS and tested my water. They told me my pH was off the charts low (some where around 5). The weird thing was no other fish seemed sick.
 
So I rushed home and added a scoop of Alkaline buffer to raise the pH. Keep in mind the only sick fish was the Bolivian at the time. As soon as I added the Alkaline, all the glo fish shot to the top and were in the corner of the tank gasping for air. My pH was only raised to about 6.4, so it wasn't too big of a jump. I now have a test kit and have tested twice a day.
 
My first question is why did the glofish shoot to the top and have trouble breathing from the Alkaline buffer?
 
Over the next few days I did about 20% water changes until I got the pH to its current level of 6.8. I have had 5 glo fish die, one every day since Sunday, and two more are sick.
 
The weirdest thing is two of the glo fish never went to the top and gasped for air. They acted like nothing has changed and are completely healthy. Also, the bolivian got healthy as soon as I fixed the pH. It blows my mind the bolivian and blue ram have been thriving through this all, while my hardy glo fish are dropping daily.
 
Why did this kill all of my glo fish? The only thing I can think of is they can't live in the acidic water of below 7 pH since they have been at or above 7 their whole life???
 
Any help is appreciated.
 
* Also, when I changed the filter I only replaced the white pad and put new carbon in it. I didn't clean the sponge or the inside of the filter. It is a Top Fin 30 rated power filter.

 

[levahe]

What is the natural pH of your water?
My advice is stop using pH buffers all together and let the fish adjust to your natural pH. unless you have a extreme ph level then there is no need to mess with it.

 

[the_lock_man]

Remember that pH is a logarithmic scale, so a jump of 1 pH level is 10x the acidity/alkalinity. To go from 5 to 6.4 in the space of a few minutes is quite a big and quick jump. I don't recommend the use of pH control chemicals because these sort of problems can occur. It seems you have quite alkali water, since you use an acidic buffer to keep it at neutral - the Blue Ram might be iffy at a high pH, but the rest should be fine in a high but stable pH.
 
The other thing about your filter is that you have beneficial bacteria growing throughout the media, hopefully you know that toxic ammonia is processed via toxic nitrite to non-toxic nitrate by bacterial colonies in your filter. When you throw away any filter media, be it pads or carbon, you are also throwing away the bacteria, so you those that you have left are unable to cope with the bioload, and this would have had a negative affect on your fish.
 
I don't recommend carbon filters at all, all the decent dechlorinators do the job that carbon is supposed to do. Keep one in the cupboard for the removal of medications, but not for normal use. With filter pads/sponges and the like, I don't recommend changing them until they are falling apart.
 
As to why not all the fish were visibly suffering, fish are like any other living creatures, their ability to withstand a poor environment differs with individuals. A Navy Seal would, I'm sure, be able to withstand being waterboarded much longer than I would. Some people have greater resistance to illness than others. Fish are no different.

 

[TwoTankAmin]

Please test ammonia and nitrite and report them. Dropping the pH rapidly into acid conditions will kill off bacteria.
 
Raising the pH up quickly turns ammonia more toxic as it rises. 6.4 isn't a problem but if it went higher fast and you had any ammonia, the pH rise really compounded things.
 
As pH  drops, nitrite becomes more toxic.
 
Using buffers takes work and paying attention.

 

[halladurg]

Thanks for the responses. Unfortunately my tap is about an 8 pH so when I add water I do add some acid buffer to lower it. I just went a little overboard this time and it ended up being disastrous. My mistake was doing it blindly but now I have a pH testing kit and won't make the same mistake.
 
One follow up question: so what is the best way to change a filter? Not at all? I thought the sponge was what held the bacteria so the filter pad could be replaced. Would it be best just to let it sit even after a few months?
 
I'm just glad my rams have made it through this.

 

[levahe]

A pH of 8 isn't too bad you could keep a very wide variety of fish in that without any problems

 

[Ch4rlie]

Yup, my tap water is usually around 8.0 pH.
 
I keep Threadfin Rainbowfish as they like that sort of pH level as well as making the water a bit brackish with tannins from wood, also heard malawi are good for high pH as well although your tank is basically too small for that.
 
Thats just to give you an idea that there are plenty of fish you can choose from that suits a high(ish) pH of 8.0.

 

[ncguppy830]

yea including livebearers