Struggling with plants in my 105 gallon.

[thisguy77724]

Ok guys, I degassed my tank water sample for two days and measured the ph with my Hannah master photometer kit and a ph tester pen and here’s the results:
PH test pen-7.1
Hannah-7.5

What does that tell us?

 

[thisguy77724]

So I lowered my ph controller down to 6.5, but the very next day I had about 5 fish die. Then I had another one die today. But the weird thing is they are not all up at the surface gasping like I’ve seen before when the ph is too high.

Any suggestions?

 

[thisguy77724]

My current parameters are:
Ammonia: .21
Nitrite: .022
Nitrate: 33.9

 

[Kwyet]

How did you get such precise measurements? Does the controller do that for you?

My first thought is that your fish needed a more gradual change in CO2 levels, but if they were acting normally that doesn’t make sense. I’m sorry you lost them! Hopefully someone else will have some insight.

 

[thisguy77724]

How did you get such precise measurements? Does the controller do that for you?

My first thought is that your fish needed a more gradual change in CO2 levels, but if they were acting normally that doesn’t make sense. I’m sorry you lost them! Hopefully someone else will have some insight.

I use a Hannah Multiparameter photometer kit.

 

[Kwyet]

I’m only finding a marine version of that. Does it work for freshwater too, or do you have a freshwater version? I know the marine nitrate checker can be converted to freshwater…

 

[BranchScape]

What are your KH, GH, and TDS ? I know you mineralize RO to roughly KH 4 and GH 6, but is that the confirmed end value in the display, or simply your target during remineralization (with actual in‑tank values potentially drifting)?

My concern is that the effective KH may be higher than expected, which could have required pushing well past ~40 ppm CO₂ to achieve that pH drop. If so, a rapid CO₂ increase combined with a sharp pH swing may have shocked the fish before any warning signs became apparent.

That said, if the true, measured KH is indeed around 4, then I’m honestly a bit stumped—sub‑40 ppm CO₂ at that buffering level should generally be well tolerated. Fish are very resilient so it takes much larger extremes to have insta death ime. Think of how they survive transport.

 

[thisguy77724]

I’m only finding a marine version of that. Does it work for freshwater too, or do you have a freshwater version? I know the marine nitrate checker can be converted to freshwater…

Yea im
Using the marine version. I was told by my lfs the values might be off slightly for freshwater but shouldn’t be significant.

 

[thisguy77724]

What are your KH, GH, and TDS? I know you mineralize RO to roughly KH 4 and GH 6, but is that the confirmed end value in the display, or simply your target during remineralization (with actual in‑tank values potentially drifting)?

My concern is that the effective KH may be higher than expected, which could have required pushing well past ~40 ppm CO₂ to achieve that pH drop. If so, a rapid CO₂ increase combined with a sharp pH swing may have shocked the fish before any warning signs became apparent.

That said, if the true, measured KH is indeed around 4, then I’m honestly a bit stumped—sub‑40 ppm CO₂ at that buffering level should generally be well tolerated. Fish are very resilient so it takes much larger extremes to have insta death ime. Think of how they survive transport.

So I checked my KH/gh yesterday and it was at 2kh and 4gh. I am using shrimp minerals powder to remineralize and brightwell more gh and sl aqua more kh to fine tune the values.

Come to think of it, I used about a turkey baster full of peroxide to try and kill some of that bba on Monday, I figured with a 105gallon tank that wouldn’t hurt anything but now I’m wondering if it caused the fish to die.

 

[JayP]

I used about a turkey baster full of peroxide to try and kill some of that bba on Monday

How big is the baster? Assuming a max dosage of 1ml per liter that's somewhere around 380ml or 12-13 oz (3% H2O2 ). Having said that, I don't think I would ever do a one day dose that large. We need our chemistry and fish vet experts. Paging Dr. @Koan

 

[BranchScape]

How big is the baster? Assuming a max dosage of 1ml per liter that's somewhere around 380ml or 12-13 oz (3% H2O2). Having said that, I don't think I would ever do a one day dose that large. We need our chemistry and fish vet experts. Paging Dr. @Koan

I can say with 100% certainty this is it. I purposefully use H2O2 during water changes on air exposed surfaces and drip it onto areas at about .1 ml doses using a syringe. This keeps it from instantly contacting fish. That volume directly into water is a sure fish killer to anything near by. APT fix will also kill a fish if applied in mass directly into the water, rip my favorite smiling acara that was too damn friendly and wanted to see what I was doing. I used maybe 2ml on that one but it swam right into the area I was treating within seconds.

 

[Kwyet]

Okay, I don’t know about the rest, but to get a more accurate nitrate reading you can mix up the packet in 17 ml of tank water and use that to fill the checker vial. @Naturescapes_Rocco also did a lot of testing and made a converter that you can download. Sorry about your fish! Also, about the peroxide, do turn off the filter for about 30 minutes while you’re using it to keep from killing the beneficial bacteria. I use a syringe to spot dose it directly into the water at much lower amounts than you used, and never had a problem. I guess I’ve been lucky, and will be even more careful now.

 

[JayP]

I use a syringe to spot dose it directly into the water at much lower amounts than you used, and never had a problem. I guess I’ve been lucky, and will be even more careful now

I do the same and shrimp and fish swim right through the resulting barage of bubbles with seemingly no ill affect, but I'd be concerned about such a large dose, even in a large tank.

 

[Koan]

We need our chemistry and fish vet experts

Well..

H2O2 actually breaks down extremely quickly into oxygen and water in our aquariums, thanks to the prodigious population of catalase positive bacteria in our biofilms

In fact common household 3% H202 is used as a rescue method for adding oxygen to shrimp tanks in case of accidental CO2 overdose. Safe 3% H2O2 levels for aquariums containing live shrimp, which are far more sensitive than vertebrates, max out at about 3ml / gallon.

Assuming a full 380ml worth of peroxide was administered, which seems unlikely that's still only around 4ml per gallon accounting for hardscape.

Even if it were persistent and not immediately breaking down, 4ml per gallon still only would be 24ppm / 24 microliters/liter

Well below any toxic level we would expect for our fish, that's less than 25%-50% of concentration safely used to medicate hatchery fry.

But again given how very quickly H2O2 breaks down in the presence of our catalase bacteria, any damage to fish to the degree of lethality would be expected within 15 - 90 minutes, not 4 days.. granted you did not pour it all directly on the fish

 

[JayP]

Well..

H2O2 actually breaks down extremely quickly into oxygen and water in our aquariums, thanks to the prodigious population of catalase positive bacteria in our biofilms

In fact common household 3% H202 is used as a rescue method for adding oxygen to shrimp tanks in case of accidental CO2 overdose. Safe 3% H2O2 levels for aquariums containing live shrimp, which are far more sensitive than vertebrates, max out at about 3ml / gallon.

Assuming a full 380ml worth of peroxide was administered, which seems unlikely that's still only around 4ml per gallon accounting for hardscape.

Even if it were persistent and not immediately breaking down, 4ml per gallon still only would be 24ppm / 24 microliters/liter

Well below any toxic level we would expect for our fish, less than 25%-50% of concentration safely used to medicate hatchery fry.

But again given how very quickly H2O2 breaks down in the presence of our catalase bacteria, any damage to fish to the degree of lethality would be expected within 15 - 90 minutes, not 4 days.. granted you did not pour it all directly on the fish

I feel very enlightened.

 

[Koan]

 

[hamfist]

Safe 3% H2O2 levels for aquariums containing live shrimp, which are far more sensitive than vertebrates, max out at about 3ml / gallon.

I'd have to challenge this. I use 1.5ml/gallon occasionally when cladogonium has appeared on shrimp and this treats the clado but is clearly very close to (or even at) the toxic levels for the shrimp , as there are often one or two subsequent shrimp deaths afterwards. THis is in situations where the clado infestations were not causing severe ill health or deaths, so the deaths seen are highly likely to have been caused by the H2O2 .
I'd be very keen not to go over 1.5 ml/gallon with shrimp.

 

[Koan]

I'd be very keen not to go over 1.5 ml/gallon with shrimp

Max threshold for death is not a good target for treatment goal yes 50% of max is the recommended safety margin for the treatment.