Water change killed half my tank?

[mimiheart]

I'm not even sure what just happened. I posted in another thread about the diatom problem I've been having in one of my tanks. This is a ten gallon with 7 juvenile (one in.) tiger barbs and five serpaes. And an ivory snail. Yesterday I put in two young male mollies to try and help with a diatom bloom.

I've been doing every other day 10-20% water changes in this tank because of the bloom.

Today I did a 50% water change in my 40 gallon and my 10. While I was filling the 40, I looked over, and saw that all of the fish in the 10 were swimming sideways or on the bottom. I grabbed the mollies and threw them back in the 40. The barbs were looking okay-ish compared to the serpaes. I got my biggest serpae who's one of my favorite fish into my 20 in a different room, where he used to live, and he rallied for a bit. Two of the smaller serpaes died in this time. The mollies were both fine in the 40 gallon. The biggest serpae was no longer rallying, I moved him closer to the filter current, but it didn't help. In the end I lost all my serpaes and at least one barb.

I have no idea what just happened. I've moved the snail out of that tank for the time being. All of the fish were fine this morning. All of my tanks get the same water/water conditioner/water temp. They do have different substrates and filters.

I haven't tested the water since I'm waiting for everything to settle post water change. But what on earth could cause them to go from being fine to dead in a matter of minutes like that? (And it really was minutes. I'd say 15 minutes tops from the time they got new water to the time they were all gone. )

My 40 gallon seems fine (though their water is low since I haven't finished filling it... maybe I won't.)

 

[DreaminginBlue]

I am so sorry to hear about your fish.
With regards to what could have caused this, the only things I can think of are ammonia in your tap water, a large temperature difference, or lack of dechlorinator.

 

[mimiheart]

The water was slightly warmer. I've tested my tap water, and no ammonia. Unless there was just a weird pocket in a bunch right there. I used the same dechlorinator I've been using and I used on my other tank. We had to leave for a few hours. Came back and one more barb is gone and another isn't looking great. Snail is doing fine and the mollies I moved out are fine.

I'm now wondering if there was some sort of pocket in the substrate that got stirred up when I added water. I'm hoping a plant from my forty gallon will help draw some of whatever it is out and put some oxygen in. I'm so upset over my serpaes. I've only had the barbs for a little bit, I was originally going to put them in the 40 gallon when they got bigger to help with population control with the mollies, but they're too aggressive. Ugh.

 

[mimiheart]

Lost another barb (the one that was looking bad) so now have a very freaked out school of four tiger barbs.

0 nitrite, 0 ammonia, 20 nitrate, 7.4 ph. Socal water hardness levels. I'm not even posting them because they're ridiculous, but they're the same they've always been.

 

[Delapool]

Is your tap water the same eg ph, etc? No concerns there? Just in case pipes were recently flushed for suburb or something.

Have you got carbon to try running that?

 

[Toad]

Are you absolutely sure you added dechlorinator to the ten gallon? It seems odd you changed water on both, but only one crashed

 

[mimiheart]

I put the water in larger buckets for changes. I put the dechlorinator directly into the buckets and then take the water from there. I don't have a better way to do changes in my house.

 

[mimiheart]

Is your tap water the same eg ph, etc? No concerns there? Just in case pipes were recently flushed for suburb or something.

Have you got carbon to try running that?

I put a new carbon cartridge in the filter. I haven't been running carbon in it before now, but I keep it on hand. I also put in aquarium salt. I gave the barbs to my lfs because it's too small a school now and I don't feel like dealing with them. I put three mollies in the tank to keep the cycle going and to continue to eat the diatoms. They've been fine. (I have mollies to spare.)

 

[Delapool]

I put a new carbon cartridge in the filter. I haven't been running carbon in it before now, but I keep it on hand. I also put in aquarium salt. I gave the barbs to my lfs because it's too small a school now and I don't feel like dealing with them. I put three mollies in the tank to keep the cycle going and to continue to eat the diatoms. They've been fine. (I have mollies to spare.)

Ok, just catching up - no difference in water or buckets or dosing used between tanks? No chance of a salt or any other overdose? (Although it would have to be a lot). Was the substrate in the 10gal very stirred up & water dirty?

Bit stuck - I'm guessing a poison over O2 loss but can't think how. I'm assuming it is either tap water, something added/not added or something in tank.

 

[mimiheart]

Ok, just catching up - no difference in water or buckets or dosing used between tanks? No chance of a salt or any other overdose? (Although it would have to be a lot). Was the substrate in the 10gal very stirred up & water dirty?

Bit stuck - I'm guessing a poison over O2 loss but can't think how. I'm assuming it is either tap water, something added/not added or something in tank.

Nope. It was the same exact water dosed with the same exact conditioner at the same dose. I see the same buckets on both tanks, though obviously the 10 gallon would have gotten more of it per capita (uh I'm not sure how to English that -- 5 gallons in a 10 gallon tank packs a bigger punch than 20 in a 40). I didn't see a big substrate stirring but I had everything turned off. The water may have been a bit cloudy/water bubbly but no more than usual.

As for salt, I keep it on hand, but don't use it in the tanks much, and never in my water change buckets. The ten gallon has had salt in it before since it's been a hospital/quarantine tank, but the substrate has been replaced since then. I wouldn't have put the serpaes in with salt with how hard my water is. I don't think the barbs would have been to happy with it either. The mollies don't care.

The mollies I have in there now seem perfectly fine. They're just nomming on the decorations and glass. One is hiding in the plants a bit, but she's always been like that, she's my shyest adult.

 

[Delapool]

Nothing popping up unfortunately - you could try a small water change and see how it goes is all I can think of.

Only other thought was if something got sprayed on buckets, etc which went into small tank but buckets would of been rinsed for larger tank water changes. Only thought of it as I sprayed the ladder today for spiders and had to remember to put hoses elsewhere for draining.

 

[TMaier]

I can't tell you how many times I have used Prime in my 3 buckets then get distracted and get down to trying to figure out which bucket I put it in verses which one still needs it....total ADD move in action.

 

[mimiheart]

I can't tell you how many times I have used Prime in my 3 buckets then get distracted and get down to trying to figure out which bucket I put it in verses which one still needs it....total ADD move in action.

The snail I had in there pre water change only moved at night. Now in the 40 gallon it's all over the place. It's either excited about being such a big tank (which seems odd) or there was something about the tank pre-water change. Still not sure what. I had that combo in there for over two months and lost the smallest barb during that time to bullying from the bigger barbs, but nothing else. And the diatom bloom might have something to do with it.

ARGH. I miss my big Serpae. We've had him for a long time.

 

[mimiheart]

Well, the girls I put into the tank are happy as can be. One had a little wound from an aggressive male that's even healing up and they're making short work of the diatoms. And the snail in the 40 gallon is also doing great. I think I'll leave it in there. I'll give the tank a week or two with the mollies in it, do a big vacuum on the gravel and water change the salt out before deciding anything else. Still would love to know what happened.