All my fish died (established tank with crystal clear water)

[cor]

For the last year I have been doing bi-weekly 20% water changes on my 125g tank with the goal of crystal clear water. I have been very easy on my 4" p-gravel as to not disturb to much and cloud up the water. I use a python and would often find pockets of bubbles in low circulation areas my rocks.

I have an AC500 and an XP3 on the tank for filtration. The temps have been around 80 and the only opening for air is the 1/3rd section of the back of the tank where the AC500 is. AM/NO2/NO3 have always been in check.

Every so often a few days after a water change my fish would be very lethargic for a couple days. I thought they were fighting and sometimes there skin would be very white and eyes cloudy(hence why I thought fighting followed by lethargic behavior). Now I think the skin problems weren't the fighting but something wrong with the water. Over the last year I have lost a fish here and there that was large and health. I had a mixed tank with CA/SAs and Africans.

Just yesterday I added a dozen African's in good health to fill the tank back up due to slowly loosing fish. I removed 2 remaining jack dempsy's from the tank and put them in another tank prior to adding the new africans. Before they went into my 125g they spent a day in my 20 long and they were looking very good and healthy. 4 hours after being in my 125g all of them had died except for a couple I saved by removing them. Both my 125g and my 20g are on the same water source and change cycle. Once I put them in the 125g they quickly started to gasp for air and their eyes clouded over.

I checked my levels and everything looked good, even better then 20 I quarantined them in. I don't have a way to check O2 levels or HS2 levels as I can't think of anything else. I'm at a complete loss here. I think the fish I had previously could handle the slow changes to whatever chemical problem the tank had but the new fish died right away. I use Amquel Plus and treat the full tank after water changes. I also have a 29g that I don't have any problems in.


My problem seems very similar to what this person has had happen: http://forum.simplydiscus.com/showt...ite-Spots-Scales-deteriorating-amp-FISH-DYING

 

[BODYDUB]

PH swing from the W/C's? Have you tested your PH form the tank and from the tap?

 

[cor]

My tap water is very hard but I didn't test the tank. I'll do that tonight.

From reading about old tank syndrom a really low ph would be the easiest answer.

 

[willis102674]

Could some type of contaminate been introduced to the tank? Get a chlorine test kit and test not only the tank water but also the tap water. I use Seachem prime with every water change. If i use any other dechlor product my fish don't act right for days. As for cystal clear water the only thing that works for me are good old fashioned magnum 350 canisters. All other filters have too much flow bypass.

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[Mount_Prion]

Bi-weekly 20% water changes aren't enough for a normally stocked tank with predatory fish.

I generally do 40-50% weekly. I suppose it could be OK if you say your parameters are fine, but to me cloudy eyes and slowly dying fish implies not enough WC. And of course it's not going to hurt you to throw some air stones in there if 02 might be a concern.

 

[ice blue]

Could some type of contaminate been introduced to the tank? Get a chlorine test kit and test not only the tank water but also the tap water. I use Seachem prime with every water change. If i use any other dechlor product my fish don't act right for days. As for cystal clear water the only thing that works for me are good old fashioned magnum 350 canisters. All other filters have too much flow bypass.

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+ 1 I'm with you on that one bro

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[cor]

My test kit only does Amonia and not Amonium so that might have been a problem as well.

I don' think it is Chlorine or Chloramine as the last change was over a week ago.

 

[1bigdovii]

If your gravel has not been cleaned enough it can form gas pockets especially under decor. Which is released when distubed I believe it is methane gas which is toxic. I tead t thread not too long ago a guy had all hia fish die after moving a large rock that hadnt been moved in a while it released gas bubbles and killed everything.

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[duanes]

If you're only doing 20% change every 2 weeks, and the substrate has lots of junk, and you have a canister that is not regularly cleaned out, your tank pH could very very acidic, and when you do a water change with hard, high pH water, the difference could be dramatic and put your fish into osmotic shock. Each 10th in the pH scale is a 10 fold difference, 7.1-7.2.
If your tank water drops to a pH of 6 before a water change, and your make up water is pH 8, that is a 200 fold difference and could be lethal.
And if there is an ammonia build up due to metabolism, adding hard water to that ammonia is also lethal.
You would be better off doing a small water change every 2 days, and make sure you clean the gunk out of filters and vacuum with each change.
That way your pH remains fairly stable and any hardness ammonia combination would be minimal.
I do water changes with my garden watering can, each time I need to water the tomatoes or flowers, I take water from the tank, instead of the tap. I even use it to flush toilets, that way I use a lot of water twice, with my fish getting the good water, and plants getting extra nitrate and other nutrients.

 

[cor]

After I test the PH after work I'll really know.

I was blind sided by this because I have been able to keep crystal clear water for a good while now but from all your insight it is apparent the water has some serious issues.