Fish Dying: pH and KH Question

[FishesForLife]

Tank

What is the water volume of the tank? 10 gallons
How long has the tank been running? ~4 years total. I moved the tank one city to another in 2017, but kept the filter, so I don’t think the bacteria got wiped out. I did treat with antibiotics about 2 years ago, and that might have wiped it out?
Does it have a filter? Yes, HOB with a sponge filter sponge on the intake.
Does it have a heater? No
What is the water temperature? 72-80F, depending on time of year and how long the light (incandescent) has been on - on a timer for 6 hours a day
What is the entire stocking of this tank? (Please list all fish and inverts.) Now down to one adult female albino cory. Previously had 4 cories. Also have anubias and amazon sword plant.

I run a bubbler in the tank 24/7.

Maintenance
How often do you change the water? Variable (please see below)
How much of the water do you change? Variable (please see below), usually about 20%
What do you use to treat your water? API Stress Coat
Do you vacuum the substrate or just the water? I vacuum obvious loose debris with every change and vacuum the gravel in sections so that everything is vacuumed about once a month

*Parameters - Very Important
Did you cycle your tank before adding fish? Yes
What do you use to test the water? API tests and a digital TDS meter
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.

Ammonia: 0
Nitrite: 0
Nitrate: 0
pH: less than 5. My test kit only reads down to 5, and it’s solidly orange
dKH: <1
TDS: 208
Current temp: 77F

my tap water
Ammonia, nitrite, nitrate:0
pH: 6.6-7.0
TDS: 80-100
dKH:1-2

Feeding
How often do you feed your fish? 6 days a week
How much do you feed your fish? 1-2 API Bottom Feeder shrimp pellets per fish or supplements like tubifex worms; what they consume in about 2 hours
What brand of food do you feed your fish? API, Hikari
Do you feed frozen or freeze-dried foods? Some freeze dried foods

Illness & Symptoms
How long have you had this fish? 4 years
How long ago did you first notice these symptoms? She started clamping her fins and not eating about a week and half ago
In a few words, can you explain the symptoms? 1.5 weeks ago, lethargy and clamped fins; yesterday, “fuzzy” appearance on body, rapid breathing, but less clamping of fins (the other two fish turned white, swam around frantically, and died about an hour later); today, skin/scales appear normal, swimming looks more normal, but seems like she’s searching for the other fish, still breathing quickly
Have you started any treatment for the illness? No, except for water changes
Was your fish physically ill or injured upon purchase? No
How has its behavior and appearance changed, if at all? Please see other sections

Explain your emergency situation in detail. (Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)

Here are my main questions.
1) How do I help this fish now?
2) Is there something specific that I did to cause this? Could they really just be dying of old age?
3) How can I safely raise and maintain the pH of this tank? I know fish can adapt to water parameters outside their “ideal” ranges, but a pH in the 4’s seems extreme? I read that cories can be sensitive to sodium, so is calcium carbonate (crushed coral), a safe alternative to buffer their tank?
4) Is it safe for me to get more cories to keep with this fish once pH situation is sorted, since they’re social and I don’t want to keep her alone? Or do you think this is a disease, and I shouldn’t risk harming more fish?

In the spring of this year, I rehabilitated a sick betta fish - injury on its back with fuzzy growth that resolved over several weeks. After the fuzz was gone and the fish appeared healthy for a couple weeks, I put it in the tank with my then 4 cories. He chased them around but did not injure them. I could tell the cories were stressed, so I removed the betta after about a week. My panda cory started flashing on the substrate the day before I removed the betta.

All the cories seemed happier with the betta gone, but then then the panda started having small white strands protruding from her sides. It looked much worse after a couple days, so I isolated her in a makeshift hospital tank. She declined rapidly, grew fuzz over her entire body, and died.

The other cories have occasionally shown similar white strands on and off since then. But they always get better very quickly.

I have been trying to fix the extremely low pH by performing water changes. I started with about once a week. That showed no improvement after several weeks, so I did daily 10-20% water changes for about a month, and finally the pH came up to about 5.2. Then I did once a week for a couple of weeks, and we’re back where we started. So I resumed the daily water changes at the beginning of this week, after the fish slowed down and stopped eating. pH is still reading <5

Of note, I did remove about a quarter of the gravel and replaced it with Imagitarium white sand last week. I also rearranged some of the decorations. I did not touch the filter. I also added a Top Fin tissue cultured plant at the beginning of this week, I rinsed it throughly before adding. I removed it when the first fish died, just in case. Could the plant have made them die? They were a little lethargic before I added the plant though.

Also of note, the remaining fish has laid eggs a few times since I started the aquarium, including while the pH is so low.

Final note, all my tanks ever, (except one shrimp tank that I changed water for every single week and kept a clam shell in (pH 6.6)) have dropped to pH </=6 after cycling. Something seems messed up? Not sure if it’s just neglected water changes when I was a kid and in college? (But again, never had nitrates above 20, ever.)

I’m at a loss at this point. My nitrates now are never above 5, and I basically never have ammonia or nitrites either. Yet I’ve rarely had good success with my tropical fish. My record for a cory cat was 6 years, but I understand they can live for 10 if properly maintained.

How do I help this poor little fish? And how do I take better care of my tanks in the future? Is insanely low pH the culprit? Or is it disease? Or both? Will adding crushed coral to introduce some buffering captivity fix my pH problem going forward?

Thanks in advance for the help!

 

[tomiyama]

Hmmm a ph of less than 5 is not good for fish, I wonder if your tank had a ph crash? Can you do some more partial water changes maybe every other day?
Do you think your test kit may have expired because it’s odd that your nitrates are at 0 even in a well maintained tank. It names me wonder if the low ph killed off some of your beneficial bacteria....

 

[FishesForLife]

Hi. Thanks for the reply!

I am equally stumped how my nitrates can be 0-5 with such a low pH? I make sure to shake the bottles before I test, and they’re in-date. So I think they’re right? Results have remained the same even after switching to new bottles of test solution.

I can certainly keep up the frequent water changes. But once the pH gets back up above 5.5 or 6, and bacteria become active again, will the tank go through a mini cycle? Could it hurt the fish? Do you think I need to add a buffer to stabilize the pH once it gets up above 6 or so?

 

[tomiyama]

i think your best bet is to gradually increase the ph and just keep monitoring your ammonia and nitrite. I don’t think your need a buffer with partial water changes as theoretically this should stabilize your system.
Your Cory is older but mine have lived to 10 years: some only live 4 years and a smaller 10 gallon is harder to take care of than a larger tank so you have done quite well. I also wonder if living alone may be stressing the Cory out as cories like living in groups of 3 or more. However I wouldn’t add another fish to your tank until you get your ph to at least 6. This will increase the chance of survival.

 

[FishesForLife]

i think your best bet is to gradually increase the ph and just keep monitoring your ammonia and nitrite. I don’t think your need a buffer with partial water changes as theoretically this should stabilize your system.
Your Cory is older but mine have lived to 10 years: some only live 4 years and a smaller 10 gallon is harder to take care of than a larger tank so you have done quite well. I also wonder if living alone may be stressing the Cory out as cories like living in groups of 3 or more. However I wouldn’t add another fish to your tank until you get your ph to at least 6. This will increase the chance of survival.

 

[FishesForLife]

Gotcha. Thank you. I will keep up with water changes to get the pH back up where it belongs and monitor water parameters closely for ammonia and nitrites. Once the pH stabilizes, I’ll plan to get her some new friends. Thanks so much for your help!

 

[AvalancheDave]

If you have soft water, water changes aren't going to increase pH/kH much. It's a lot of work for little result.

 

[Frank the Fish guy]

What is the pH and KH of your source water?

If you are using the API KH test, then when you add 1 drop and the color changes, that could mean that your KH is zero. That would explain the low pH and the lack of nitrates. With no KH there is no cycle happening since some KH is needed for the cycle. That's a classic KH crash. Your buffers all used up, perhaps because of what little there were to start with.

The KH buffers replenish slowly from the air, and from any crushed coral or limestone rock you have in the tank, but if the bio filter is using it faster then it can be replenished, then the tank is crashed and will die.

You can add some baking soda to get your buffers back up to a good level. Around 5 degrees is commonly recommended as a minimum to avoid a crash. I keep mine at 8 degrees. The minimum anybody recommends is 2 degrees.

 

[FishesForLife]

Hi. Yes, my source water has dKH 1. And the tank has dKH 0. I would happily add in a buffer, but I am worried about adding anything with sodium for a cory cat? Is baking soda safe for her? If so, can I just throw in regular old Arm and Hammer from the grocery store, or do you get something specific for the aquarium?

Is crushed coral safer for her because it’s calcium based instead of sodium based?

Thank you so much for taking time to help me figure this out!

 

[Frank the Fish guy]

The key thing is to use the measured KH value to set the amount of buffer that you add. Don't look at the pH value which will bounce. Just look at the KH. The KH number will go up in proportion to the amount of buffer you add.

You can keep your tank a 'soft water' for your Corys, by setting the KH value around 5 degrees or even less down to 2. But you need to be above 0! That makes it soft, like your Cory's natural environment and will keep the sodium low too in proportion. Keep the GH low (salts) to keep your tank 'soft'. The GH is what the soft water fishes are sensitive too.

 

[AvalancheDave]

I've been using Arm and Hammer baking soda as well as potassium bicarbonate with clown loaches for years now. Just add a little, wait, then measure pH. You'll soon get an idea of how much you need to add. I add 4 grams daily.

 

[FishesForLife]

Gotcha. I’m slowly bringing up the alkalinity.

Now my question is, since this poor cory cat is alone now, I assume I’ll need to get her some buddies pretty soon? (She’s been climbing the front wall of the tank all day.) Obviously, I need to get the KH straightened out before adding any more fish. But do you think I should totally reset the tank - bleach or boil everything? Just because I don’t know for certain what killed the other two fish, and I think disease is a strong possibility. I have a 3 gallon tank that I could put the remaining fish (Pop) in for a few weeks while I clean and then cycle the 10 gallon. Or do you think that will be too stressful for her? And maybe it’s a moot point anyway because I’ll be putting the same fish back in the tank, so she’ll just “contaminate” it again?

Thanks again for your advice!

 

[Frank the Fish guy]

What is the pH and KH of your source water?

 

[FishesForLife]

pH 6.6-7.0
KH 1-2

 

[Frank the Fish guy]

Right. That is the source of your problem. Low KH water. The KH will get exhausted in the aquarium. Then the pH will crash and the fish will die.

Get used to buffering your water. Lots of us do.

 

[neofyt05]

Hello, I have been reading an article about how pH tests do not work well when the alkalinity is close to zero. So with 0KH you can't really measure the pH. Slowly increase your KH and try again.