Help! Old tank syndrome

[k0olmini]

Hey everyone I think I’m running into old tank syndrome. I had a group praecox rainbows and lost half of them. Added in another group to refill it and all of them died. So now Im left with my original 4. I’m using the co op test strips and my water parameters are pH 6.8, hardness over 300, and low buffer. My tank is heavily planted with pogo octopus and duckweed (yay…)
 

@Coryhas been saying he is changing less water, so I tried adopting this method. Yet when going back, the cause of old tank syndrome is not changing water often enough….I’ve got a feeling I should just change water haha. Thoughts?

[nabokovfan87]

What is your care schedule?
Dosing, WC, feeding, etc.

OTS can come in a few ways, so it's important to understand why.
 

 

[PineSong]

I would change water, but since your goal is to make water habitable for new fish without stressing out/losing your old fish, I would do it gradually rather than a drastic change all at once. 

Using my 20g as an example, I usually do 1/3 water change every two weeks, but if I had skipped water changes for months and just topped it off, I would not want to start with such a big change. I might do 25% on Sunday, 25% on Wednesday, 25% on Saturday, 25% on Wednesday again, then wait til Sunday and do a 50. At that point, I might do two 50% changes the next week and then try new fish--if they were out of quarantine.

 

[k0olmini]

On 6/15/2022 at 1:03 PM, nabokovfan87 said:

What is your care schedule?
Dosing, WC, feeding, etc.

OTS can come in a few ways, so it's important to understand why.
 

 

I feed 6 times a week. Water changes, I’m at about 30% every 2 months. 
 

I think I phrased my issue wrong. Cory said he’s been changing water less so I’ve been doing that, but how is he avoiding OTS

[PineSong]

On 6/16/2022 at 2:55 PM, k0olmini said:

I feed 6 times a week. Water changes, I’m at about 30% every 2 months. 
 

I think I phrased my issue wrong. Cory said he’s been changing water less so I’ve been doing that, but how is he avoiding OTS

Doesn't Cory have auto water change systems?

I think there is a lot of gray area between 30% a week and 30% every 8 weeks, so if OTS is the issue responsible for the new fish dying, you don't necessarily have to go all the way to weekly water changes to improve your outcome.

The way I interpret the video above is that frequent small water changes aren't removing as much of the bad stuff as you might think, so once in a while you need a big enough water change plus removal of solids (through external filters or vacuuming) to really reduce the "old tank" factors. How often "once in a while" is will depend on things like stocking levels, plant volume, and whether you plan to introduce new fish who will be hurt by the 'old tank-ish' parameters.

[nabokovfan87]

On 6/16/2022 at 1:17 PM, PineSong said:

The way I interpret the video above is that frequent small water changes aren't removing as much of the bad stuff as you might think, so once in a while you need a big enough water change plus removal of solids (through external filters or vacuuming) to really reduce the "old tank" factors. How often "once in a while" is will depend on things like stocking levels, plant volume, and whether you plan to introduce new fish who will be hurt by the 'old tank-ish' parameters.

There's 2 scenarios described.  Let me re-watch and try to break them down.

Scenario 1: Not Changing Water

-Topping off the tank only (PH slowly decreases over time)

-Letting nitrates build up and stay high

-Overfeeding in addition to the above

Scenario 2: Not Enough Maintenance

-Not changing enough water volume

-Not changing water often enough

-Not maintaining the system via gravel vac or via cleaning the filtration (build up of the off-colored M&Ms)

-Overfeeding in addition to the above

 

On 6/16/2022 at 11:55 AM, k0olmini said:

I think I phrased my issue wrong. Cory said he’s been changing water less so I’ve been doing that, but how is he avoiding OTS

It depends on the system itself.  You're feeding heavily, he might not be.  You might have more fish in the tank.  You might not have plants to take in nitrates.  Your plants might not be taking in as much nutrients as his do.  There's many variables here.  I understand how it seems "fine" to follow something you saw in an online video, especially one from Cory.  I would listen to what he says in the video.

"We don't have a very good methods to measure what's going into the tank. We measure the results. As long as we do our WC we get into this lull. We change our oil every 3,000 miles but are shocked when our transmission breaks. We're doing our maintenance, but we're not really testing the overall system. Most people don't even have a hardness test kit.

How do we fix OTS? The easiest way is to just up the water changes.  If you're doing 10% every week, maybe it's better to do 30% every other week.

I'm a big fan of automating your water changes. That's what I do. of I like to do 30-40% once a month.  Kind of bigger water changes and I'll adjust as necessary.  I might reduce the amount of fish I keep, I might change the quality of food (dry vs. frozen), or maybe increase to about 50% WC. I don't like doing more than that at any one time because you can run out of hot water and it's a more stable environment at 50% of less.  Typically once a month I'm servicing the filter and maybe gravel vac as well."