Hyposalinty, what went wrong?

[SNAKEMANVET]

Sorry to hear that 125mph,at least you are doing it right this time.

 

[jcw]

Most likely, the pH itself didn't do this, which is another point to mention. When pH changes, the toxic ammonia will rise/fall along with oxygen levels. pH is basically a quality stamp of a lot of other things, like Alkalinity, or KH.

So, this is a bit nitpicking, but the real reason may be that you increased the toxic ammonia while doing this, and total ammonia is hard to monitor, unless you go for the seachem instruments.

When this is said and done, the pH was the killer indirectly. Bakingsoda and ammonia alert is also a key ingredience in this equation to successfully drop the S.G.

I agree that pH itself isn't likely the killer of fish. I've been googling trying to see why ro/di in old saltwater might make things worse.

But with a drop in pH, ammonia should be in its less toxic form ammonium.

It's something, though. And it doesn't happen to everyone.

I've even used tap water and salt mixed at 1.009 let sit for a couple days and fish do great being transferred right into it. better than adding ro/di straight to old saltwater.

 

[125mph]

So you don't think PH is the cause? The alk tested normal and temperature was great. I had a 200gph pump to make sure there was enough aeration. The tank was 15gallons.

The ammonia was undetectable. I thought that was the killer but when I tested, it showed nothing. I don't think ammonia could kill fish that fast anyway.

 

[SNAKEMANVET]

I put ro-di water in with my old saltwater when I was dropping my salinity.I had no detectable ammonia and ph stayed steady.I was putting in 5 gallons of ro-di and wait about an hour and remove 5 gallons of saltwater.It took about a week to bring down to the required salinity.I did this in my dt with live sand and liverock.Because I was basically doing water changes to bring down the salinity I was removeing any ammonia from die off.When you do this too a small tank like 15 gallons,just doing a 0ne gallon ro-di with effect the ph.I don't think adding ro-di to old saltwater will cause enough ammonia to kill fish. jmo

 

[125mph]

I put ro-di water in with my old saltwater when I was dropping my salinity.I had no detectable ammonia and ph stayed steady.I was putting in 5 gallons of ro-di and wait about an hour and remove 5 gallons of saltwater.It took about a week to bring down to the required salinity.I did this in my dt with live sand and liverock.Because I was basically doing water changes to bring down the salinity I was removeing any ammonia from die off.When you do this too a small tank like 15 gallons,just doing a 0ne gallon ro-di with effect the ph.I don't think adding ro-di to old saltwater will cause enough ammonia to kill fish. jmo

Ya I'm thinking the small tank and replacing salt water with RO to bring down salinity caused the PH drop which killed the fish. I would have done it in my DT but I have corals and inverts in there which couldn't be moved.

 

[sandwi54]

I still believe a drastic pH change is the cause here. Ammonia becomes LESS toxic when pH drops (and the OP verified that the ammonia is undetectable). For those of you who had no issues replacing water with RODI, it's because you changed only a small amount of water at a time (hence why it took you a week to get down to 1.009). The pH change was gradual and fish adjust their osmoregulations in time.

It's possible that something else caused the fish to die, but judging from what I read - pH went from 8.2 to 7.5 in 24 hours with two water changes, that is the main cause. The first water change probably brought pH from 8.2 to perhaps 7.8, and the second from 7.8 to 7.5. That's a pretty big pH shock to me.

To the OP, you may want to check your RODI's pH. It should be pretty close to 7. The tap water in my county is basic (actually close to the saltwater's pH) at around 8.2-8.3 from the water treatment, so technically I could just dump tap water into my tank without any issues, but of course I wouldn't do that

 

[SNAKEMANVET]

:thumbsup: I totally agree with you.

 

[125mph]

It's possible that something else caused the fish to die, but judging from what I read - pH went from 8.2 to 7.5 in 24 hours with two water changes, that is the main cause. The first water change probably brought pH from 8.2 to perhaps 7.8, and the second from 7.8 to 7.5. That's a pretty big pH shock to me.

Actually it was a gradual drop in 24 hours (from 1.025 to 1.015). I removed about 3 gallons of saltwater at a time and added small amounts of water every 1-2 hours until it hit the top of the tank, then repeated the process. But overall the PH did drop fast in the 24 hrs period.

 

[evsalty]

A cycled QT is going to need liverock/sand, and I'd highly suggest putting neither liverock or sand into a qt tank. They make dosing harder as they absorb and leech any medication you put into it.

You do not need sand or rock in a tank to have a cycled tank! The sand and rock allow for MORE areas for bacteria to cutivate but the bacteria can live on any surface in that water column. My QT is a 20g and it stays running 24/7 with bare bottom and just a plastic house in it for the fish to hide out in. I use a Fluval with just floss in it. I have dropped the salinity fast by pulling 10g's out and replacing with RO/DI while fish were in it and nothing happened to the fish. I would think that the combo of an unestablished tank with a high bioload for its size coupled with the ph swing would be the cause but not just the ph.

 

[MrTuskfish]

You do not need sand or rock in a tank to have a cycled tank! The sand and rock allow for MORE areas for bacteria to cutivate but the bacteria can live on any surface in that water column. My QT is a 20g and it stays running 24/7 with bare bottom and just a plastic house in it for the fish to hide out in. I use a Fluval with just floss in it. I have dropped the salinity fast by pulling 10g's out and replacing with RO/DI while fish were in it and nothing happened to the fish. I would think that the combo of an unestablished tank with a high bioload for its size coupled with the ph swing would be the cause but not just the ph.

I think it is the filter media (floss) that is culturing aerobic bacteria. A tank, without a lot of porous material (like filter media) cannot keep ammonia down without massive WCs. Glass and plastic are not suitable for establishing any kind of bio-filter. Substrate & LR is not a good idea, because they absorb meds; but a filter is great for a QT. This forum has a constant threads that involve ammonia build-up in bare QTs.

 

[sandwi54]

Actually it was a gradual drop in 24 hours (from 1.025 to 1.015). I removed about 3 gallons of saltwater at a time and added small amounts of water every 1-2 hours until it hit the top of the tank, then repeated the process. But overall the PH did drop fast in the 24 hrs period.

You did the right thing by doing small water changes to let fish adjust for pH change over long periods of time. Next time you can add baking soda to boost and buffer the pH of the new water and you shouldn't have any problems.

 

[evsalty]

I think it is the filter media (floss) that is culturing aerobic bacteria. A tank, without a lot of porous material (like filter media) cannot keep ammonia down without massive WCs. Glass and plastic are not suitable for establishing any kind of bio-filter. Substrate & LR is not a good idea, because they absorb meds; but a filter is great for a QT. This forum has a constant threads that involve ammonia build-up in bare QTs.

Yes there was MORE aerobic bacteria on the floss but I had a month of no Fluval and just a powerhead in the tank and still had my 1 fish that was a perm resident survive. That fish is still with me. The bacteria does not need media nor substrate to live. It can indeed live on any and all surfaces in the tank.

Those threads about ammonia build-up usually are from tanks that do not stay running year round.

 

[steelhead77]

Wow! More than likely if you had just left the fish alone, they would have been just fine. This is EXACTLY why I advocate a wait and see approach to situations such as this. Time and again we see on this forum, well meaning reefers try and do the right thing only to have it go horribly bad for the fish.

Sorry for the loss. Next time just try and relax and give it a few days to a week or so and see what happens. Ich is not a fast killer, nor neccesarily a killer at all. Not everything you read here about ich and quarantine is gospel. Some people have success battling Ich without doing anything other than keeping fish stress free and water params pristine.

 

[jcw]

I don't know how "low" pH kills fish.

I know how ammonia and nitrite at higher levels kills. But I don't know how a 7.5 ph kills a fish.


My tank has measured 7.5 in the AM. 8.4 in the afternoon. The fish do fine.

A fish mailed in a bag overnight drops pH to 7.5 and frequently even lower. The fish survives.


I don't know how a pH of 7.5 or greater kills a fish.


IMO, there is something else we're missing.

 

[125mph]

Wow! More than likely if you had just left the fish alone, they would have been just fine. This is EXACTLY why I advocate a wait and see approach to situations such as this. Time and again we see on this forum, well meaning reefers try and do the right thing only to have it go horribly bad for the fish.

Sorry for the loss. Next time just try and relax and give it a few days to a week or so and see what happens. Ich is not a fast killer, nor neccesarily a killer at all. Not everything you read here about ich and quarantine is gospel. Some people have success battling Ich without doing anything other than keeping fish stress free and water params pristine.

Well.. I knew the ich wasn't going to be a problem for the 6 fish in the tank. They were very healthy and eating well. A few were starting to get the white spots on the fins and I figured worse case maybe 1-2 would die and the rest would go immune. But, I didn't want the tank to be infested with ich and new additions would be faced with ich :mad2: ... However, all I read about hypo was that it was very safe.. Something went wrong and I thought it was PH but now I'm questioning that theory based on some recent posts.

Maybe it was aeration? It was a 15g tank with 6 fish, all of which were around 1.5 to 2.5". I was running a heater stable at 77.5' and a rio 800 powerhead (211 gph). That was all that was running on that tank.

Old saltwater at 1.025 was made, and I diluted it with RO water. Then over the next 24 hrs I removed 3 gallons, then slowly added RO (probably 1 liter at a time) and repeated. The end salinity at 24 hrs was 1.015 so it never even got to 1.009 before it was over.

 

[sandwi54]

Well.. I knew the ich wasn't going to be a problem for the 6 fish in the tank. They were very healthy and eating well. A few were starting to get the white spots on the fins and I figured worse case maybe 1-2 would die and the rest would go immune. But, I didn't want the tank to be infested with ich and new additions would be faced with ich :mad2: ... However, all I read about hypo was that it was very safe.. Something went wrong and I thought it was PH but now I'm questioning that theory based on some recent posts.

Maybe it was aeration? It was a 15g tank with 6 fish, all of which were around 1.5 to 2.5". I was running a heater stable at 77.5' and a rio 800 powerhead (211 gph). That was all that was running on that tank.

Old saltwater at 1.025 was made, and I diluted it with RO water. Then over the next 24 hrs I removed 3 gallons, then slowly added RO (probably 1 liter at a time) and repeated. The end salinity at 24 hrs was 1.015 so it never even got to 1.009 before it was over.

Did you see your fish gasping for oxygen? 6 fish in a 15g tank could be low on oxygen. Did you point the powerhead at the water surface for aeration? Running an airstone will help as well. QT typically doesn't get nearly as much oxygen as the DT and you might want to run a large airstone in the future.

A pH of 7.5 will not kill fish short-term, but a fast change from 8.2 to 7.5 will. We don't know how fast the pH shifted for you (since you said you added new RODI water to the QT slowly) so it's hard to determine the cause in this case. Keep in mind that even a sudden change of 0.1 in pH is stressful to fish. If you remember high school chemistry, pH is on a logarithmic scale. That means a change of 1.0 in pH equates to a change of 10 times in hydrogen ion concentration. A change of 0.1 is 1.26 times. That means when pH goes from 8.2 to 8.1 suddenly, the fish has to cope with a sudden 125% rise of hydrogen ions. It may not appear large to us but it definitely is to marine fish. A continual sudden drop of 0.1 pH, at a time, from 8.2 to 7.5 in a number of hours IS highly stressful to fish.

Remember, we are talking about a SUDDEN change, not a gradual change. A typical tank's pH may swing from 7.8 to 8.2 in a day, but that's a gradual change. when we do water change without matching pH, the change of pH happens in a matter of seconds.

I am speaking from personal experience as I have killed fish by doing the exact same thing as you did, when I first started out in the hobby and didn't know how pH works. I now know better.

 

[jcw]

Maybe it was aeration? It was a 15g tank with 6 fish, all of which were around 1.5 to 2.5".

If I had to guess, this was the problem more than pH.

 

[125mph]

If I had to guess, this was the problem more than pH.

There was a lot of water movement in the tank though because the powerhead was very strong for the small tank. I always assumed water movement brings in air?

 

[SNAKEMANVET]

You need to break the waters surface with a powerhead to exchange carbon dioxide and oxygen,with a qt tank that small a air stone would work.

 

[125mph]

You need to break the waters surface with a powerhead to exchange carbon dioxide and oxygen,with a qt tank that small a air stone would work.

Hmm air was the issue then. I thought running a powerhead would create air, but it never broke the surface.