Tank of doom, SOS

[Ksven]

My boyfriend has a 75 gallon tank that is literally a doom tank. Everything dies eventually sooner than it should. To count this tank has claimed 2 plecos, 9 tiger barbs, 2 Cory cats all one by one.

Now bare with me.
I asked him to test his water today
0 ammonia
40 nitrate
2.0 nitrite
8.0 ph
80°
Weekly 30% changes treated with aquarium salt and dechlorinator

Plan is
Large water change, clean tank, fill with treated water and then treat whole tank with aquarium salt, hopefully lower nitrites
Day after test PH and use either ph up/down to balance to 7

Currently homes 1 small parrot, 3 black tetras, 2 yo-yo loaches, 1 silver dollar and 2 small Cory’s
We understand the mix is not ideal but it’s nit what started in this tank, more like fish saved from someone who was just going to flush them, so please keep focus on just tips to get this tank to be a safe home.

 

[Colin_T]

Two issues straight out.
1) Nitrite will kill fish and having 2.0ppm of nitrite is bad and an indication the filter is not working properly.
2) Salt will kill softwater fishes like plecos, tetras, barbs & loaches if they are exposed to high levels, or if they are exposed to salt for too much time. It damages their kidneys and they have organ failure.

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How long has the tank been set up for?
How do you clean the filters?
What media (materials) do you have in the filters?
Do you gravel clean the substrate when you do a water change?
Do you dechlorinate the new water before adding it to the tank?
What chemicals (if any) do you add to the tank?

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You should do bigger water changes. I recommend doing a 75% water change and gravel cleaning the substrate once a week.

You do water changes for 2 main reasons.
1) to reduce nutrients like ammonia, nitrite & nitrate.
2) to dilute disease organisms in the water.

Fish live in a soup of microscopic organisms including bacteria, fungus, viruses, protozoans, worms, flukes and various other things that make your skin crawl. Doing a big water change and gravel cleaning the substrate on a regular basis will dilute these organisms and reduce their numbers in the water, thus making it a safer and healthier environment for the fish.

If you do a 25% water change each week you leave behind 75% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

Fish live in their own waste. Their tank and filter is full of fish poop. The water they breath is filtered through fish poop. Cleaning filters, gravel and doing big regular water changes, removes a lot of this poop and makes the environment cleaner and healthier for the fish.

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You should have some floating plants in the tank to reduce the light. It will also give the silver dollar something to eat. Water Sprite (Ceratopteris thalictroides/ cornuta) and Duckweed are both great plants to have in the tank. You can grow them outside in a pond or plastic storage container and when the silver dollar has eaten the plants in the tank, you take some from the pond and put it in the tank.

 

[Ksven]

Two issues straight out.
1) Nitrite will kill fish and having 2.0ppm of nitrite is bad and an indication the filter is not working properly.
2) Salt will kill softwater fishes like plecos, tetras, barbs & loaches if they are exposed to high levels, or if they are exposed to salt for too much time. It damages their kidneys and they have organ failure.

------------------------
How long has the tank been set up for?
How do you clean the filters?
What media (materials) do you have in the filters?
Do you gravel clean the substrate when you do a water change?
Do you dechlorinate the new water before adding it to the tank?
What chemicals (if any) do you add to the tank?

------------------------
You should do bigger water changes. I recommend doing a 75% water change and gravel cleaning the substrate once a week.

You do water changes for 2 main reasons.
1) to reduce nutrients like ammonia, nitrite & nitrate.
2) to dilute disease organisms in the water.

Fish live in a soup of microscopic organisms including bacteria, fungus, viruses, protozoans, worms, flukes and various other things that make your skin crawl. Doing a big water change and gravel cleaning the substrate on a regular basis will dilute these organisms and reduce their numbers in the water, thus making it a safer and healthier environment for the fish.

If you do a 25% water change each week you leave behind 75% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.

Fish live in their own waste. Their tank and filter is full of fish poop. The water they breath is filtered through fish poop. Cleaning filters, gravel and doing big regular water changes, removes a lot of this poop and makes the environment cleaner and healthier for the fish.

------------------------
You should have some floating plants in the tank to reduce the light. It will also give the silver dollar something to eat. Water Sprite (Ceratopteris thalictroides/ cornuta) and Duckweed are both great plants to have in the tank. You can grow them outside in a pond or plastic storage container and when the silver dollar has eaten the plants in the tank, you take some from the pond and put it in the tank.

The tank has been set up for about six months

I believe he cleans them( filters) in the water he’s changing out of that makes sense but I can’t be positive, and he’s asleep right now and I don’t know much about the filters

He does clean the gravel when he does water changes
I did suggest doing bigger water changes, I had the same thought.. we have a 10 gallon and 30 gallon and never have issues but I think in retrospect it’s because they’re getting a lot of water taken out compared to this 75 gal

The water is dechlorinated before it goes into the tank, so aquarium salt and the dechlorinator all that goes in

We did have duckweed, need to get more!


What’s your recommendation for salt use?


We’ll definitely bump the water changes way up, we’re so upset seeing these guys go thanks!

 

[Colin_T]

Salt should only be used to treat fish for certain diseases and should not be added to aquariums unless there is a disease that needs treating.

The following link has information about what to do if your fish get sick. It's long and boring but worth knowing. It has a section at the bottom (post #2) about using salt.
https://www.fishforums.net/threads/what-to-do-if-your-fish-gets-sick.450268/

I would not be adding salt to the tank.

I would do bigger water changes to get rid of the nitrites. You should do a 75% water change and gravel clean any day you have an ammonia or nitrite reading above 0ppm, and any time you have a nitrate reading above 20ppm.

 

[AbbeysDad]

In an established tank you should never be able to measure ammonia or nitrites as there should be sufficient beneficial bacteria to keep them in check. Nitrates at 40 is too high as you want <=20 (or even lower as/if possible)!
NEVER add salt to a freshwater tank unless you're using salt and high temperature to treat a disease like ich...and even then, this is best done in a bare bottom hospital tank. Salt has long been considered therapeutic in the hobby, but it can be hard on fish and plants and is really unnecessary.
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> So as mentioned, you need increased volume/frequency of partial water changes - perhaps 50%+ twice a week until water params look better. Perhaps the bio-media needs a closer look to ensure it's the best platform for BB???
> STOP adding salt.
> Step up gravel cleaning and use extra care when cleaning filter media to preserve beneficial bacteria.
> As Colin mentioned, fast growing floating plants are great at indirectly reducing tank ammonia, nitrites, and nitrates as they will use ammonia as their nitrogen source (so it doesn't get oxidized into nitrites and nitrates by beneficial bacteria.)

 

[Naughts]

Most people on here are adverse to PH up/down because it leads to big fluctuations which are a lot more dangerous than a constant PH.
I used it once and a few days later a blue shrimp died. Never again! After reading about the surrounding science on here, I threw it away.

 

[AKfish]

I agree with most things that have already been said. Your levels you need a big water change. You bio load isn't very big so your probably having an issue because you have WAY WAY too much substrate (gravel) in your tank. I recommend pulling more then half out ASAP!! When substrate is too deep no amount of vacuuming will get it clean. Therefore bio mass rots and creates nitrogen pockets in your substrate. Then you stir it around during a water change breaking up these pockets and releasing it into the tank. This creates a large flux and when you add new water it's already contaminated. Leaving your fish in just as bad a situation. Therefore slowly killing your fish one by one over time due to poor water quality. Hope hat helps and keeps more fish from dien. All the best to ya. Oh I recommend bringing your gravel down to where it's about even with the black plastic trim on the bottom of your tank. That's will be plenty of substrate.

 

[FishGuest5123]

Well, I’m going to throw everything off here. An established tank shouldn’t register any nitrites so I question if the tank is even cycled. I don’t know why it wouldn’t be after 6 months but it happens sometimes. I would do a big water change and then buy a bottle of Safe Start + to put in your filter and around the tank. If you use Seachem Prime, don’t use it for the first 24 hours as it can destroy the Safe Start. Use another dechlorinator for the first 24 hrs then you can go back to Prime if you use it. I wouldn’t move any of the gravel right now as it holds a lot of the beneficial bacteria. Test the tank every couple of days and don’t do any water changes unless your test show high ammonia, nitrites, or nitrates. Once you get the ammonia & nitrites down to 0 you can do a large water change to get nitrates down to 20ppm or below. Good luck!