Bottomfeeder die off... pH crash?

[cwt]

I'm having a bad week in my main 29G tank; cories are dying and the algae eater is about to as well. Guppies and cherry barbs are showing no symptoms, which surprises me as the barbs are the oldest fish I have. The tank could be a bit cleaner, I've been away and left the thing on auto-feeder for about a week. Before I left the pH had been creeping upward, which I took as a good thing because it had been too low for a long time... was about 7.4/7.5. Now it's back to 6 or below on the API test. Filtration has been changed a couple of times, but the bio-stone parts are always left in; no indication of any ammonia or nitrite in tests.

This tank has been in place for 3 years with a variety of plants and fish; I'm wondering, is it time to start over?

 

[Copachick]

I hope someone answeres this... because I may have the same issue. Two of my Otos and snail died within the past week or so. My Ph is like 6.. if not a smidge lower, I cant tell. I dont know why? My numbers have always been good in there.

 

[bruinsbro1997]

Did you possible add these fish recently? If so it could be pH shock. Maybe you have what is called Old Tank Syndrome, it usually happens when you've had a tank for a while and you could be treating it a bit better. pH lowers eventually, from what I have read pH lowers naturally unless you put buffers in a tank, however I don't know how accuarate that statement is. Here is a link to an article on Old Tank Syndrome that might solve your problem:

Old Tank Syndrome

 

[cwt]

these are all old fish, except for the guppy/endler offspring.

Hmm, good point... I didn't test for nitrate yet. I used to have a huge java fern bundle in the center of this tank but removed it after it got hard and knotty... maybe the remaining plants can't keep the NO3 at bay.

I generally buffer the water I add, but did not the last time or two. Also, this is the only tank in which I have to buffer... the others stay close to the pH of the tap water which is around 7.7-7.8.

 

[cwt]

An additional thought is that around here (central Ohio), we had a very wet spring, followed by a short but very active planting period out in the agro areas. Then, big rains. I wonder if the nitrates in the tap water are high because of that...

 

[eco23]

How often do you do pwc's on your tanks?

There shouldn't be any need to add any buffering products as long as you do frequent water changes unless your water is EXTREMELY low in alkalinity. The buffering agents can also cause pH fluctuations in the tank which can be harmful to your fish.

 

[cwt]

tap water here is hard (gH) but low in calcium activity.

I don't do pwc nearly often enough, and rarely a large one (25%). At this point a big water change and replant/regravel may be required; I'll post an update when I get a chance.

 

[eco23]

tap water here is hard (gH) but low in calcium activity.

I don't do pwc nearly often enough, and rarely a large one (25%). At this point a big water change and replant/regravel may be required; I'll post an update when I get a chance.

From what I know of Old Tank Syndrome, it does sound like a good possibility. Weekly pwc's are really an important aspect for tons of reasons. First and foremost the nitrAtes need to be ideally kept at or below 20, and unless you have a very heavily planted tank, that number will continue to climb. Also the nitrification process will consume buffers and nutrients in the water which stabilize pH and keep the fish swimming happily. There's a lot of other aspects of why a healthy pwc routine is necessary...but we'll stick with those 2 for now. If changing the water is difficult or hard to find time for...it's worth investing in a water changing system like a Python or Aqueon water changer. I can do a 50% pwc and gravel vacuuming on my 46 gallon in about 5-10 minutes.

 

[cwt]

Update: Essentially, all that are left are guppies now; I moved a few fish out of this tank to other ones, and they've generally survived. I'm starting to think it's short on oxygen, bacterial issues, or a combination of the two. Time to start this tank over. I've done manual water changes in the past, maybe the Python is a must for the next build.

BTW, either I have a bad nitrate test, or I just don't get nitrates in the water... comes up < 5 ppm every time.

 

[logansmomma1228]

I hope someone answeres this... because I may have the same issue. Two of my Otos and snail died within the past week or so. My Ph is like 6.. if not a smidge lower, I cant tell. I dont know why? My numbers have always been good in there.

Are the otos new? I can never keep Otos alive, I have heard they are tough to take care of depending on where you got them from due to them being so weak from shipping/etc.

As far as OP's issue, is there maybe something that got into the tank that shouldn't have? What kind of substrate do you have; sand can have air pockets in it that can be stirred up by cories and release toxins into the water.,



I apologize if some of my info is off, I'm a little rusty. Haven't been on in a while, but just trying to help


EDIT:OK disregard the comments about your tank cwt, it appears you guys have figured out the issue. How old is your test kit? I believe they are supposed to last a while but I'm not sure how long.

 

[cwt]

the API test kit is the one I bought 3 years ago when I started doing the fish thing; I have since bought new ammonia and pH chems for it, and have a hardness test which I rarely use.