Not eating , dying after water change

[shamik]

I've a simple setup with 55g tank with 7 discus [ had, just lost 2 ] . Eheim canister filter, aeratorrs, driftwood , 2 anubias and eheim heater maintaining around 85 DF. Fishes are around 4 inches.
The setup was running since last November, strategy was 90% water change every 2-3 days. Nitrogen safe level and PH ~ 6. Since last 2 months, i started observing after water change the fishes lie flat on tank bed for 10-15 mins and then do heir normals. Is this usual ?
Issue:
Last water change, they did the same. However, since then stopped eating. Very unusual for them. They started swimming at the top of the tank.
Waited around 20 hrs, things didn't improve. I gave potassium permanganate, kept them in for around 10 mins. Then hydrogen peroxide to normalize PH. 90% water change + seachem safe. Removed food on floor.I've done this process earlier and helped fishes.
However, this time - after overnight - i found 2 large ones dead on floor. Others are hovering at the top, not eating. Please advise, here is my tank video -https://youtu.be/EnvOTDAIjNU.

[White Worm]

Do you use water conditioner? Age water or straight from tap?

[shamik]

I use tap water and pinch of seachem safe to take care of chlorines.

[Bizarro252]

What is your PH directly out of the tap vs the tank? Do you age the water (if needed to match tank PH) If not aging water do you use warm water to match temp? If not you could be temp shocking them, and if you are maybe something changed with your water heater, hot water can harbor not only bacteria (if not kept hot enough) but also build up of heavy metals within the water heater itself.

[shamik]

PH out of tap is around 6.8 [historic data - December 2016] . I don't age water, I do get mixed water out of tap to limit temperature shock +/- 2 DF. No work was done to water heater, however - that also doesn't rule out something have build up over time. What's the quickest petsmart way to determine ? What correction would you suggest to my process.

[Ryan925]

PH out of tap is around 6.8 [historic data - December 2016] . I don't age water, I do get mixed water out of tap to limit temperature shock +/- 2 DF. No work was done to water heater, however - that also doesn't rule out something have build up over time. What's the quickest petsmart way to determine ? What correction would you suggest to my process.

I use prime not safe but I believe when you are dosing safe you need to know the level of chlorine or chloramine in your water and dose accordingly. Maybe your source water has higher chlorine or chloramine levels and you are no longer dosing enough safe.

[shamik]

Safe states that over doze don't hurt, i add a pinch ( as per label) - will be a bit more generous.

[White Worm]

I would make sure you have lots of air (surface agitation). Looks like suffocation. Do 50% every other day and see of you have similar problems. 90% WC from tap has very little oxygen and a lot of dissolved gas. Make sure refill is splashing into tank as you fill. JMO

[Bizarro252]

I use prime not safe but I believe when you are dosing safe you need to know the level of chlorine or chloramine in your water and dose accordingly. Maybe your source water has higher chlorine or chloramine levels and you are no longer dosing enough safe.

Just to add, I did ask Seachem directly about Safe because I was using it to pre-mix my own 'Prime' to use when recharging Purigen because you need to use SO MUCH Things I learned:
*You CANNOT treat Safe as a powdered version of Prime Concentrate as I thought, you cannot pre-mix Safe with water, once mixed in water it is only effective for 24 hours.
*Safe will NOT neutralize heavy metals, prime will, but even then only in low amounts at normal dosing.
*No slime coat benefits from Safe.

[Davidzil]

PP would kill all bacteria, you would be back to cycling the tank. Looks like something going on with the water or your use of Safe.
If you can set up another tank with aged water and see.

[MarkGSmith]

You need to check your source water occasionally. It is not always as stated on the water company website. This last month my TDS has gone from a stable 250 gradually down to 80. Previously stable for 3 years.

[Second Hand Pat]

PP would kill all bacteria, you would be back to cycling the tank. Looks like something going on with the water or your use of Safe.
If you can set up another tank with aged water and see.

Not exactly true. Depends on the dose.
Pat

[shamik]

PP would kill all bacteria, you would be back to cycling the tank. Looks like something going on with the water or your use of Safe.
If you can set up another tank with aged water and see.

I'm observing dull bubbles on the top of the tank, switching off canister filter. Any suggestions will help. Rising temperature to 90 DF.

[Bizarro252]

You need to check your source water occasionally. It is not always as stated on the water company website. This last month my TDS has gone from a stable 250 gradually down to 80. Previously stable for 3 years.

Same, I check my KH/GH now and then, dropped from ~9 (~160ppm) to 6 (~100ppm) once it started to warm up around here. PH stayed the same however...8.2

[Bizarro252]

PH out of tap is around 6.8 [historic data - December 2016] . I don't age water, I do get mixed water out of tap to limit temperature shock +/- 2 DF. No work was done to water heater, however - that also doesn't rule out something have build up over time. What's the quickest petsmart way to determine ? What correction would you suggest to my process.

I would age your water, tap being 6.8 and tank being at 6 per your posts that is not only a pretty large shift, but in the acidic direction, which as far as I understand is rougher on the fish. Your fish could be showing these issues due to the repeated PH shock.