ACK!!! Nitrates from nowhere and a PH drop too!

[maxwell1295]

Let me start from the beginning...

I did a 25% PWC in my 58G Saulosi tank yesterday evening. I woke up this morning to find all of the fish at the top of the tank gasping for air. I was rushing out for work so I didn't have much time to do anything. I did test for ammonia, which was at 0ppm. Temp was 80*, which is what I have that tank set at. I did a quick 25% PWC with double the amount of dechlor I normally use....just to be on the safe side. Since there seemed to be a lack of oxygen, I also set up an air pump with 2 airstones.

When I got home, the fish were fine. I ran some more tests and saw that the PH was at about 7.4 (it's usually at 8.0). Did I forget to use buffer when I did the 2nd PWC? Hmmmm.....I'm pretty sure I didn't forget since I am a creature of habit and I measure everything before starting a PWC. Anyway, I added enough baking soda to slowly bring the PH back up to the 8.0 it normally is. The fish were fine, eating well, and swimming around like always. I turned off the airpump and pulled the airstones. Everything was back to normal. I was relieved.....until it happened again tonight!

So I tested for everything again with these results:

Ammonia - 0ppm
PH - 7.4 8O
KH - 13
Nitrate - <5ppm
Nitrite - .25ppm 8O
Temp - 80*

How does the PH drop like that when the water is so well-buffered?

Could the rise in nitrite have that kind of an effect on the PH?

How the heck can I have a nitrite spike on an established tank that has never shown anything but perfect parameters? In fact, I'm so meticulous that all of my tanks have pretty much the exact same parameters.

A few more things:

1. My tap has not changed at all from what it previously was. PH, KH, ammonia (0), nitrite(0), and nitrate (0) are the same.

2. I have not added anything new to the tank since it was set up.

3. Dechlorinator is Cloram-X. I use 1.5 tsp per 40 gals of water (50% extra).

5. The filters (Eheim 2217 and 2213) have not been serviced for about 3 weeks now. I can't see what would make these filters recycle. They are packed with biomedia that has not been disturbed. The flow on them is still very strong, so I have no intention of doing any maintenance on them.

I have been running air through the AC50 powerhead to oxygenate the water for about 1/2 hour after this last episode. pH has risen to 7.8 without me doing anything to it (no buffers or PWC). I'm still getting a .25 nitrite reading.

I may have to swap out the 2217 with one of the 2217's I have on the 55G.

 

[coldmachineUK]

A nitrite spike suggests a problem in the tank itself, rather than with the water you're using for pwcs. It fits with the fish gasping too.

My guess is you have lost a fish perhaps (?) or there is decaying debris somewhere (if it's a saulosi tank I'm assuming you have a lot of rockwork, so it could be trapped somewhere between stones). Debris that's not siphoned up can also lead to a drop in the pH.

But, I know how experienced you are with keeping fish and these are fairly 'obvious' things as far as it goes. I'm only assuming that you may have missed them by focusing on more complex causes, I'm certainly not suggesting you wouldn't know about them!

Also, I've not heard of baking soda being used to buffer water before :S Have you tried adding some limestone-type rocks in or something instead? I'm lucky to have very alkaline (7.8 ) and hard water where I live, so buffering has never been a huge issue, but in all my travels I've not heard of that method before! If you've used it over the years it must work though. I'd add rocks to the tank rather than anything to the water though, but that's me

 

[maxwell1295]

Well, I looked around the tank and did find a dead fish this morning. It looks like it got stuck because it was lodged in between two rocks. The only problem is I don't know whether this happened before or after the rise in nitrate.

I keep the air on last night and kept it one when I left for work this morning. The fish were doing fine. Water tested at about 7.8 with 0ppm nitrite, so maybe things are headed in the right direction. In all the time I've been keeping tanks, this is the first time I've seen any kind of mini-cycle, hence the panic on my part...

 

[hc8719]

pH levels usually drop at night, its normal. it sounds like you checked the pH levels later, thought it might be that

 

[maxwell1295]

This turned out to be a case of surface agitation....as in not enough! I ended up submersing the 2217 spray bar and pointing it up towards the surface. I also added a 2nd powerhead lower in the tank to help with water movement. The dead fish was most likely a result of CO2 poisoning (or lack of O2). All is well now. In fact, I had some spawning going on yesterday and now have 2 holding moms in the tank! I guess they are doing just fine....

 

[An t-iasg]

Sorry that you lost a fish I'm glad everything turned out well! Good luck with the fry!