My 75gl is crashing, again. :-(
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My 75gl is crashing, again. :-(

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My 75gl is crashing, again. :-(
Old 02-13-2011, 01:11 PM   #1
 
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My 75gl is crashing, again. :-(

I did a water change to my 75gl yesterday and woke up this morning to find all fish breathing hard and fast, the Denisons were at the surface gulping air. I immediately lowered the water level below the filter output, creating a gushing waterfall into the tank and dropped an airstone into the tank. Within 15 minutes all fish were breathing and behaving fine, and are now looking for food.
Water parameters are ph 7.4, amm 0, nitrite 0, nitrate 10 ppm.
Prior to the water change params were ph, 7.4, amm 0, nitrite 0, nitrate 20 ppm.
(Note: all tanks got their w/c yesterday, only this one is having a problem)

What the heck is going on with this tank?? What causes a lack of oxygen in the water when water parameters are testing negative for ammonia and nitrite??
I'm starting to feel like I should never do water changes on this tank. The water source for my discus tank and this one are the same, only coming from different taps in the house. I checked water parameters from both taps, numbers are exactly the same across the board.

Before I tear out the rest of what remaining hair I have left can someone please tell me what the heck is going on????
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Old 02-13-2011, 03:01 PM   #2
 
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I'm totally hypothesizing here, not knowing your tank info, but if the tank is heavily planted and you did a late afternoon(?) water change, could it be a combination of high dissolved CO2/low O2 in the source water, and the plants pulling O2 from the water at night? Does the filter actually disturb the surface tension normally and how might your filter/plant setup differ from your other tanks?

For what it's worth, municipal water systems are mandated to keep the pH within a couple of tenths of neutral pH, based on conversations I've had with water system employees, assuming you don't have a well.

David
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Old 02-13-2011, 06:33 PM   #3
 
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Quote:
Originally Posted by DKRST View Post
I'm totally hypothesizing here, not knowing your tank info, but if the tank is heavily planted and you did a late afternoon(?) water change, could it be a combination of high dissolved CO2/low O2 in the source water, and the plants pulling O2 from the water at night? Does the filter actually disturb the surface tension normally and how might your filter/plant setup differ from your other tanks?

For what it's worth, municipal water systems are mandated to keep the pH within a couple of tenths of neutral pH, based on conversations I've had with water system employees, assuming you don't have a well.

David
I did the water change at 5pm, same time as I did the discus tank. This tank is planted 50% heavier than the discus tank. I do not have well water. The discus tank and the community tank each have a Fluval 405, but the discus tank also has a built in wet/dry.
The filters do not disturb surface tension in either tank.
So high dissolved CO2/low O2 source water would cause what I'm seeing??
The only other thing I can think of is that some type of heavy metal is being dispensed from the bathroom sink that isn't from the utility sink??
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Old 02-13-2011, 06:51 PM   #4
 
Whats your heat at? Higher temperatures means less oxygen
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Old 02-13-2011, 06:58 PM   #5
 
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Oh, Kymmie, not again! Sorry to hear that.

It does sound like a low O2 problem since your fish improved as soon as you added an airstone and dropped the water level and your water params are fine. Sorry I can't offer any more advice. Hope you get it resolved soon.
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Old 02-13-2011, 07:26 PM   #6
 
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Unless something is really strange with your household plumbing, there shouldn't be any difference between water from one household faucet and any other.
Based on what you describe, it may be an O2 thing, but I'm still thinking CO2. Tap water can be pretty low in O2 and high in CO2 out of the tap, but even dispensing it into a bucket should transfer significant O2 into it and "take" CO2 out. How do you change the water? Do you run it into a bucket? I'm asking primarily to see if there is opportunity to transfer gasses into/out of the new water.
Regarding high CO2 levels, I'm not familiar with the behavior of fish under high CO2 levels - do they gasp in a manner similar to low O2?
Vigorous aeration will help in the case of low O2, by improving water movement and O2 saturation, but it also helps CO2 (reducing it) even more quickly since the partial pressure of CO2 (pCO2) in water is much lower than O2.

All guesswork om my part, but if fish show the same gasping behavior in Low O2 and High CO2, I'd bet on high CO2 levels, depending on how you manipulate the water during the water change...

David
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Old 02-13-2011, 09:06 PM   #7
 
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Quote:
Originally Posted by DKRST View Post
Unless something is really strange with your household plumbing, there shouldn't be any difference between water from one household faucet and any other.
Based on what you describe, it may be an O2 thing, but I'm still thinking CO2. Tap water can be pretty low in O2 and high in CO2 out of the tap, but even dispensing it into a bucket should transfer significant O2 into it and "take" CO2 out. How do you change the water? Do you run it into a bucket? I'm asking primarily to see if there is opportunity to transfer gasses into/out of the new water.
Regarding high CO2 levels, I'm not familiar with the behavior of fish under high CO2 levels - do they gasp in a manner similar to low O2?
Vigorous aeration will help in the case of low O2, by improving water movement and O2 saturation, but it also helps CO2 (reducing it) even more quickly since the partial pressure of CO2 (pCO2) in water is much lower than O2.

All guesswork om my part, but if fish show the same gasping behavior in Low O2 and High CO2, I'd bet on high CO2 levels, depending on how you manipulate the water during the water change...

David
I do the water change the same way for both tanks, via a lead free marine hose straight into the tank.
The end of the hose is clamped on to the side of the tank, I have a nozzle on the end of the hose, I have it open to a "shower" setting and it sprays the new water into the tank.
If it is a CO2 issue shouldn't the exact same thing be happening in the discus tank, and my three other tanks?
This just started happening this month, to this tank, and this tank only.
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Old 02-13-2011, 09:23 PM   #8
 
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Oh, Kymmie, not again! Sorry to hear that.

It does sound like a low O2 problem since your fish improved as soon as you added an airstone and dropped the water level and your water params are fine. Sorry I can't offer any more advice. Hope you get it resolved soon.
Yes, again. At least this time I caught it well before the fish were having serious trouble and didn't lose any. All this discussion about O2, high CO2, dissolved gases.....I don't understand it. Why didn't I pay better attention in science class?!?! Wwwaaahhh!!!
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Old 02-13-2011, 09:23 PM   #9
 
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Do you inject CO2? I'm assuming, based on above that you dont?
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Old 02-13-2011, 09:32 PM   #10
 
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Okay, I just took this off of a website. So, maybe it is high CO2 that is causing this problem. This tank is very heavily planted, thick, thick, thick. I did the water change at 5 pm, which left only four hours of light left for the day. This still wouldn't explain why the other tank didn't have this problem, as it is planted, just not to the extent that this one is. The article also talks about temps rising but the tank is maintained at a constant 78.

"Carbon dioxide is an odorless, colorless gas produced during the respiration cycle of animals, plants and bacteria. All animals and many bacteria use oxygen and release carbon dioxide. Green plants, in turn, absorb the carbon dioxide and, by the process of photosynthesis, produce oxygen and carbon-rich foods. The general formulas for plant photosynthesis and respiration are summarized below.

Photosynthesis (in the presence of light and chlorophyll):
Carbon dioxide+WaterOxygen+Carbon-rich foodsCO2H2OO2C6H12O6
Respiration:
+ Oxygen Carbon dioxide + Water
Carbon-rich foods+OxygenCarbon Dioxide+WaterC6H12O6O2CO2H2O
Green plants carry on photosynthesis only in the presence of light. At night, they respire and burn the food they made during the day. Consequently, more oxygen is used and more carbon dioxide enters waterways at night than during the daytime. When carbon dioxide levels are high and oxygen levels are low, fish have trouble respiring (taking up oxygen), and their problems become worse as water temperatures rise. As you can see from the table, even small amounts of carbon dioxide can affect fish.
Its lucky for fish that "free" carbon dioxide (by "free" we mean it is not combined with anything) levels rarely exceed 20 mg/L (milligrams per liter), because most fish are able to tolerate this carbon dioxide level without bad effects.
When several days of heavy cloud cover occur, plants ability to photosynthesize is reduced. When that happens in a pond containing lots of plant life, fish can be hurt in two ways: by low dissolved oxygen and by high carbon dioxide levels.
Carbon dioxide quickly combines in water to form carbonic acid, a weak acid. The presence of carbonic acid in waterways may be good or bad depending on the waters pH and alkalinity. If the water is alkaline (high pH), the carbonic acid will act to neutralize it. But if the water is already quite acid (low pH), the carbonic acid will only make things worse by making it even more acid."
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