Tank Kills Everything

[Kaleigh]

So I have a 20 gallon I’ve had set up for about 5 months now. It’s planted with some driftwood and sand. I have 2 mystery snails, a nerite snail and a trapdoor snail (plus babies now - oops). Anyways, anytime I add fish they die within a few days and it seems to happen so fast I can’t catch what’s going on. 
I first put a school or runny nose tetras in there that were mailed to me - half died in transport so I had went to get some more at my LFS so they wouldn’t be stressed by having inadequate numbers. A couple days go by and they seem to adjusting fine and eating well - then I see one that looks like he has a messed up eye - like it’s squinty. So I’m confused - I go to Facebook and get a ton of diff suggestions. I didn’t have any meds on hand (I now have the coop trio of meds) - so went to a big box store and got some ich stuff but by the time I could treat them after work half of them were dead. I then added the meds and the other half died in the next 12 hours - so within 24 hours they were all dead. It was my first fish dead and devastating. So I waited a couple months and my snails seemed fine. I obviously did big water changes and stuff but everyone assured me that nothing would survive the tank. 

so I then decided to get one dwarf gourami - seemed fine for the first day and then next morning he seemed to be struggling to breathe but I could see no visual signs of anything. I took even more of my floaters off the top and I have 2 sponge filters with air stones running - so I don’t think it was lack of oxygen. 
 

finally I just went to get a trio of guppies as my last attempt and sure enough they are dying. I can’t see any visual signs but they seem to be breathing heavy. I have no idea how to treat my tank in an attempt to save them?! Or even so I can keep fish in this tank. I have 2 other tanks with no issues so this one is killing me. I’m also newer to the hobby 

my tank parameters are:

ammonia 0

nitrite 0

nitrates 20-40 ppm depending on day 

pH 8

im really hoping I don’t have to tear the whole tank down and start all over again - help please 

[xXInkedPhoenixX]

Hi. Not much to tell from what you have so far, happen to have any pics of the tank now, then and maybe of the sick fish so we can see what you saw? That might help diagnose what may be going on.  What are you using for filtration, chemicals if any, lights, cleaning, anything that might give a more complete picture to help. 

Edited July 7, 2021 by xXInkedPhoenixX
Typos are lame

[CalmedByFish]

On 7/6/2021 at 9:24 PM, Kaleigh said:

 I have 2 other tanks with no issues

See if you can think of anything about this tank that's different from the other 2.

Like a substrate, plant, or decor that the others don't have. Or maybe you put some aquarium-related chemical into the water that didn't go into either of the other 2 tanks. Or if it's in a location away from the others, I would be wondering about household chemicals (window cleaner, air freshener, etc).  

Maybe something invisible got in. I've heard of people putting their hands in a tank without realizing they had on lotion or sunscreen. Or maybe an object in the tank (or the tank itself) came in contact with soap. (I once had to take apart and vinegar a 55 gallon because I got dish soap in it.)

Totally just brainstorming here, but my initial thought is that *something* is in the tank that's not in the other 2.

[ARMYVET]

My suggestion is to do another water change and add some purigen to the filter and let it go for a week.   I’m willing to bet it will turn black.  
Get 2 pouches if purigen…let the one go for a week then take it out and clean and recharge if it is dark brown to black…put second one in. While cleaning the first. Do that a couple times and hopefully that should get out whatever invisible toxin you have in there unless you have something that is continually leeching into the tank.

[Colu]

Did you use a water dechlorinator like prime when doing water changes 

[Kaleigh]

Here’s a picture of my tank and then the rummynose that I first had (the only fish I’ve seen any evidence of something going on), and a picture of the gourami I had. 
Filtration is 2 medium sponge filters with air stones. I am using prime at water changes cause I’m using water from the faucet - which I use on all my tanks. I have Nicrew lights on all my tanks running. I do a 50% water change typically once a week. 
The only thing different in this tank is this is my first time with wood in my tank - I bought some for aquariums specifically and boiled it for almost 4 hours before placing into the aquarium. I guess this is the only tank without a lid - so maybe something did get in there? We don’t use aerosol or anything necessarily as I’m extra cautious about what gets in there. But would extra water changes and maybe a lid help to eliminate this path?

I’ve never heard of Purigen! I’ll have to look into it to see how to use it. 

[Colu]

Have you tested your tap water I don't think the wood would have cause any of these problems

Edited July 7, 2021 by Colu

[CalmedByFish]

When you look at the Purigen, research what exactly it takes out of the water. Surely there are some types of toxins it can't remove, and it'd be worth knowing.

Do either of the other 2 tanks have that same wood, from the same source, prepared in the same way, in the same pot? 

[Kaleigh]

No this is the only tank that has wood in it, I’ve never used it before. 
 

My tap water parameters are 

.25 ammonia

0 nitrite 

8.4 pH 

5 nitrate 

[Guppysnail]

Off the wall here but your uplift to be seems to be right at the water line…snails can surface to breathe fish can’t. Maybe your water is not oxygenated enough? 

[Bobbie]

This may also be completely unrelated to the dead fish, but what did you boil the wood in? A regular pot? Did you make sure it was completely clean beforehand - if there was something like washing up liquid in the pot the wood may have absorbed it

[eatyourpeas]

It seems something got in the tank. Do you burn scented candles? Is the tank near a kitchen? Not having a lid makes the tank vulnerable to airborne chemicals. Good call on the air supply, @Guppysnail

[Kaleigh]

@Guppysnail I def have some room to put more water in, I just kept it lower to keep snails from wandering but sounds like I need a lid anyways. I’ll try that!

@Bobbie yeah i used an old stock pot we don’t use often - I rinsed it out prior but that’s it. So I guess it could be a factor 

@eatyourpeasno candles or oils, we don’t do really scented stuff at all in our house and the tank is upstairs in a bedroom, so it’s away from the kitchen. If I wanted to rule this out, what would I do? Would I have to scrub the whole tank down and start my cycle all over again?

[CalmedByFish]

Considering that your other tanks don't have the wood, and that the pot was merely rinsed first, that seems like it needs investigated further. 

To get soap residue off of anything (a pot, the tank, decor, your hands if you want to find all your papercuts), rub the item with undiluted white vinegar. I'd suggest not using a rag, since it too has probably been exposed to a form of soap. I either use my bare hands, or clean paper towels. 

Then rinse rinse rinse. 

If I remember right, soaps do something to fishes' gills, making it hard to take in oxygen. Even a tiny amount of soap can do it. 

(I don't know if wood can be vinegared successfully.) 

Edited July 8, 2021 by CalmedByFish

[eatyourpeas]

On 7/7/2021 at 8:31 AM, Kaleigh said:

.25 ammonia

Any ammonia can kill your fish. It may be that you would need to try a different water like RO/DI and see if that helps. Is your tap water from an underwater source? Are your other tanks showing the same amount of ammonia? If not, something in the tank is fouling the water.

[Harley]

Let me know if you figure something out because I have the same thing going on minus the snails

[HH Morant]

I have done 50% water changes with 0.5 ppm ammonia in the tap water. The ammonia - 0.25 ppm in the tank after the water change - was gone within 12 hours. The filters, the plants, and the tank processed that much ammonia in that short time, and the fish showed no signs of distress. That was double the ammonia reported here.

I know that doesn't help much to solve the mystery of the killer tank.

Is there a spouse or housekeeper who cleans around the tank? Someone who might not be so careful about getting a little bit of cleaning product in the tank? Kids who might want to play with the fishies when you are not around?

Like @Guppysnail, I noticed that the lift tubes of the sponge filters are at the surface, which would limit and perhaps prevent aeration. That would be consistent with the labored breathing of the fish before they died. I am not sure that fish deaths with very light stocking - like these - could be from lack of aeration, but maybe that is why it took a few days for the fish to die.