The best thing you can do is stir up the substrate whenever you do water changes. This will keep the substrate from getting too compact........IMO....
BTW, Matak..I was just kidding......
BTW, Matak..I was just kidding......
pockets anaerobic gas are no myth....unfortunately
- Thread starter gregga
- Start date
I'd like to find out how to prevent this as well, if it's possible...
Isn't it kind of a no-no to stir up the gravel? I thought that it would end up suffocating the beneficial bacteria colony by burrying them. I would lean more towards the idea of gently dragging an ice-pick (or chopstick) through it. How deep is "deep substrate"? 3"- 5"?
Isn't it kind of a no-no to stir up the gravel? I thought that it would end up suffocating the beneficial bacteria colony by burrying them. I would lean more towards the idea of gently dragging an ice-pick (or chopstick) through it. How deep is "deep substrate"? 3"- 5"?
each to a corner
Isn't this fun? Two knowedgable folks politely trying to show us what actually happened. And a ringside seat too! OK, Wetman, you go into this corner here. No, the other one. That's it. You have explained a plausible chemical reaction but not defended RTR's statement that the gas was probably CO2 or N2, not the gas you need for your explanation.
RTR, please take the other corner over there. Good. You have rebutted Wetman admirably but not offered an explanation of what actually killed the fish.
Gentlefolk, go at it.
Isn't this fun? Two knowedgable folks politely trying to show us what actually happened. And a ringside seat too! OK, Wetman, you go into this corner here. No, the other one. That's it. You have explained a plausible chemical reaction but not defended RTR's statement that the gas was probably CO2 or N2, not the gas you need for your explanation.
RTR, please take the other corner over there. Good. You have rebutted Wetman admirably but not offered an explanation of what actually killed the fish.
Gentlefolk, go at it.
Plus, I get to cut n' paste relevant paragraphs from www.skepticalaquarist.com and you'all (especially RTR) get to pull them to shreds. Then I sneak back to my cubbyhole and revise...
Thus:
"As pH drops, more and more ammonia is ionized to non-toxic ammonium. Here's a useful rule-of-thumb for the ammonia/ammonium ratio: for every one unit decrease in the pH measurement there's about a ten-fold decrease in the percentage of toxic ammonia. At pH 7.0 ammonia is about 0.33% of TAN, at pH 6.0 toxic ammonia represents only 0.03% of the total. The temperature comes into play also: at higher temperatures, more of the TAN is toxic ammonia. At 82oF there's almost twice as much non-ionized ammonia as there is at 68o, if the pH remains the same. There's a good presentation of these processes in a fact sheet posted by the University of Florida's Soil and Water Services Dept. at http://edis.ifas.ufl.edu/FA031. Their Table 1 shows the relationships of non-ionized ammonia (NH3) to pH and temperature. With the table you can calculate the fraction of toxic un-ionized ammonia represented by your ammonia test's TAN at your pH and temperature levels."
I've been going on the basis of this table. (follow that hyperlink).
RTR's right about the way bacteria with different metabolic requirements tend to stratify themselves in an undisturbed sediment. It's a question of opposed gradients, with, for examples, diminishing supplies of oxygen and nitrogen diffusing down that interface with diminishing supplies of oxidizable sulfide diffusing upwards. Each kind of bacteria find an ideal niche, stabilized by the metabolic requirements of their neighbors in the strata just above and just below.
One way to avoid troubles is to have a substrate that's no deeper than plant roots require (and aquatic plant roots tend to grow sideways into a mat called the "rhizozone"), and that's not enriched with sulfur-laden biodegradable organic matter (like fishfood stirred down there at the last gravel vacuuming).
The question in retrospect is, would gregga's fish have survived if the water had been drawn down, but the substrate remained undisturbed? I think they would have been done in by the ammonium/ammonia conversion anyway. RTR doesn't think so.
Thus:
"As pH drops, more and more ammonia is ionized to non-toxic ammonium. Here's a useful rule-of-thumb for the ammonia/ammonium ratio: for every one unit decrease in the pH measurement there's about a ten-fold decrease in the percentage of toxic ammonia. At pH 7.0 ammonia is about 0.33% of TAN, at pH 6.0 toxic ammonia represents only 0.03% of the total. The temperature comes into play also: at higher temperatures, more of the TAN is toxic ammonia. At 82oF there's almost twice as much non-ionized ammonia as there is at 68o, if the pH remains the same. There's a good presentation of these processes in a fact sheet posted by the University of Florida's Soil and Water Services Dept. at http://edis.ifas.ufl.edu/FA031. Their Table 1 shows the relationships of non-ionized ammonia (NH3) to pH and temperature. With the table you can calculate the fraction of toxic un-ionized ammonia represented by your ammonia test's TAN at your pH and temperature levels."
I've been going on the basis of this table. (follow that hyperlink).
RTR's right about the way bacteria with different metabolic requirements tend to stratify themselves in an undisturbed sediment. It's a question of opposed gradients, with, for examples, diminishing supplies of oxygen and nitrogen diffusing down that interface with diminishing supplies of oxidizable sulfide diffusing upwards. Each kind of bacteria find an ideal niche, stabilized by the metabolic requirements of their neighbors in the strata just above and just below.
One way to avoid troubles is to have a substrate that's no deeper than plant roots require (and aquatic plant roots tend to grow sideways into a mat called the "rhizozone"), and that's not enriched with sulfur-laden biodegradable organic matter (like fishfood stirred down there at the last gravel vacuuming).
The question in retrospect is, would gregga's fish have survived if the water had been drawn down, but the substrate remained undisturbed? I think they would have been done in by the ammonium/ammonia conversion anyway. RTR doesn't think so.
Wait a minute! Cut and pasting from your own site?! THAT doesn't sound too sound. Could've made it all up!
j/k (Raises poster that says "skepticalaquarist.com #1")
Getting back to RTR's statement, unless there was a ph swing (which most likely wouldn't have been since gregga is an experienced hobbyist), the ammonium to ammonia swing doesn't seem likely. If, however, it had been a while since water changes then maybe...
How about it gregga?? Any rotten egg smell before your loss? Which, by the way, I'm sorry to hear!
I didn't check out the ammonia ionization chart from the site, but if my "Fish Hatchery Management" book has it, I'm sure it's everywhere.
j/k (Raises poster that says "skepticalaquarist.com #1")Getting back to RTR's statement, unless there was a ph swing (which most likely wouldn't have been since gregga is an experienced hobbyist), the ammonium to ammonia swing doesn't seem likely. If, however, it had been a while since water changes then maybe...
How about it gregga?? Any rotten egg smell before your loss? Which, by the way, I'm sorry to hear!
I didn't check out the ammonia ionization chart from the site, but if my "Fish Hatchery Management" book has it, I'm sure it's everywhere.
RTR hasn't posted a link to his good article on "Old Tank Syndrome": http://www.tomgriffin.com/aquasource/oldtanksyndrome.shtml
(btw, the Skeptical Aquarist site got started as a way to keep from re-posting the same material over and over... )
(btw, the Skeptical Aquarist site got started as a way to keep from re-posting the same material over and over... )
Love these acronyms - TAN = Total Ammoniacal Nitrogen (i.e., the total nitrogen from both ammonia and ammonium).
My argument is just that anyone who fiddles with the tank other than straight water changes with any positive, hobby-kit detectable ammonia reading is a fool. Ditto anyone who would do a log pH change is equally a fool. That is a ten-fold change - and while I generally agree w/wetmanNY that most "pH shock" jest ain't so, 10x change is beyond the Pale.
I get substrate bubbles, but I do plenums and I bet on N2 (no odor). I do have denitrification going on actively in those tanks.
My techniques for avoiding anoxic pockets:
In planted tanks use any depth of substrate desired, but plant heavily and renew the substrate every 1-3 years by cleaning out the old organics (largely dead root mass - swordplants, dense crypt stands, and Val stands are all offenders here).
In unplanted tanks have no more than 1" of substrate unless it is RFUG and full-depth vacuum with every partial - if you cannot cover the entire area each partial, mark with a rock/pebble and start there next week. Don't use sand. I know it is popular now, but I have had problems in the past and have long ago given it up. My techniques, not yours, my choice.
BTW, I disagree with the concept of a rhizozome applied to fish tanks. IME, the roots go down to the bottom of the tank, period, even with >6" of substrate or with plenums. They will generally occupy the full depth, only certain plants root as much laterally as vertically (Crinums are notorious). Crypts and Val send out prominent runners with development of daughter plants (vegetative propagation), but each plantlet roots vertically - check where the plants hit the glass and run along it.
BTW, The Skeptical Aquarist is one of the safest sites to cut and paste from - even if I don't 100% agree with all of it. I don't even 100% agree with stuff I wrote a few years ago.
My argument is just that anyone who fiddles with the tank other than straight water changes with any positive, hobby-kit detectable ammonia reading is a fool. Ditto anyone who would do a log pH change is equally a fool. That is a ten-fold change - and while I generally agree w/wetmanNY that most "pH shock" jest ain't so, 10x change is beyond the Pale.
I get substrate bubbles, but I do plenums and I bet on N2 (no odor). I do have denitrification going on actively in those tanks.
My techniques for avoiding anoxic pockets:
In planted tanks use any depth of substrate desired, but plant heavily and renew the substrate every 1-3 years by cleaning out the old organics (largely dead root mass - swordplants, dense crypt stands, and Val stands are all offenders here).
In unplanted tanks have no more than 1" of substrate unless it is RFUG and full-depth vacuum with every partial - if you cannot cover the entire area each partial, mark with a rock/pebble and start there next week. Don't use sand. I know it is popular now, but I have had problems in the past and have long ago given it up. My techniques, not yours, my choice.
BTW, I disagree with the concept of a rhizozome applied to fish tanks. IME, the roots go down to the bottom of the tank, period, even with >6" of substrate or with plenums. They will generally occupy the full depth, only certain plants root as much laterally as vertically (Crinums are notorious). Crypts and Val send out prominent runners with development of daughter plants (vegetative propagation), but each plantlet roots vertically - check where the plants hit the glass and run along it.
BTW, The Skeptical Aquarist is one of the safest sites to cut and paste from - even if I don't 100% agree with all of it. I don't even 100% agree with stuff I wrote a few years ago.
Wow, a 30 second killer? That's some crazy stuff...
That's sucks....Sorry about your loss...
I guess I don't have to worry about that too much because I vacuum my gravel when I do water changes.
That's sucks....Sorry about your loss...
I guess I don't have to worry about that too much because I vacuum my gravel when I do water changes.
Hey Beviking........
There was no noticeable "rotten egg" smell while moving the tank. For what it's worth I tested the water about 1 week before the "accident" and less than 2 hours afterward. There was only a .2 change (8.0 to 7.8).......................Gregg
There was no noticeable "rotten egg" smell while moving the tank. For what it's worth I tested the water about 1 week before the "accident" and less than 2 hours afterward. There was only a .2 change (8.0 to 7.8).......................Gregg
