Aeration not optional?

[asincero]

For a while I've used a bubble wall to not only get the cool bubbling effect, but to aerate the water. Since the tank is fairly heavily planted, I figured the plants supplied all the O2 the fish would ever need so the bubble wall was primarily for looks. However, I've noticed that everytime I turn off the bubble wall for any length of time (say 24 hours), the fish would come to the surface and act like they're gasping for air. Actually, only the mollies would do that. My loaches still always appeared to behave normally.

Two weeks ago, I added even more plants. These new plants didn't really attach itself to the gravel as strong as the plants I already had in there, so I decided to turn off the bubble wall for good because it stirred up the water too much. Yesterday, I noticed one of my male sailfins acting very listless and hanging out near the surface gasping for air. Today that sailfin is dead, along with another molly! :sad:

I'm starting to think I need to have more aeration in the tank and just having plants are insufficient. The last time I had any signifcant molly deaths was when I didn't use a bubble wall. Then I started using one, and I stopped having dead fish. Then two weeks ago I stopped the bubble wall, and now I have two dead fish. I tested the water parameters, and pH is where it's always been (around 7.6). No ammonia, no nitrites but nitrates is a little high being over 40ppm but less than 80.

Anyway, anybody wanna add there thoughts? I was under the impression that using bubble walls are bad for planted tanks because it causes disolved CO2 to be released from the tank. And now, I'm thinking of adding a pressurized CO2 system to the mix. :help:

 

[Roan Art]

. . .
I was under the impression that using bubble walls are bad for planted tanks because it causes disolved CO2 to be released from the tank.

That is correct and they are unnecessary so long as you have adequate filteration and current in the tank.

I stock rainbowfish in almost all my tanks (from 36g to 75g), which are heavily planted, and they are very O2 intensive fish. I also run filters at both ends of the tanks with the spray bars/outflow positioned so that there is a current running mid-level to bottom to circulate the water and minimize any dead zones. The only time I've had problems with O2 is when my CO2 goes over 25ppm, which is about the limit for bows.

Let's look at your tank: how big is it and what type of filteration are you using? Do you have a powerhead at all?

Roan

 

[asincero]

Let's look at your tank: how big is it and what type of filteration are you using? Do you have a powerhead at all?

It's a 36g corner tank. The filter I'm using is a Rena XP2 canister filter.

However, I just remembered something...the water temperature is around 87 degrees F. Since warm water doesn't hold as much O2 as cooler water, perhaps this is the reason the fish seem to be suffocating when I turn the bubbles off?

I have had the bubbles on for the past two hours right now and the mollies are clearly more lively, swimming around, and picking on the algae thats growing on the rocks.

When I was poking around the back of my tank where the foilage is thickest, I found another dead molly . That brings the deathtoll to 3. :sad: And I was doing so well without any major fatalities for months!

 

[asincero]

Hmm ... after doing some googling on powerheads, I've come to the hypothesis that perhaps it's not the supposed "aeration" that the bubbles are producing that the fish need. But rather, it's the current being produced.

I have the intake tube and spray bar of the filter on the same side of the tank. I'm guessing this arrangement doesn't produce much circulation. Perhaps positioning a powerhead at each of the three corners of the tank will produce the circulation I need?

 

[Roan Art]

WHOA! Why do you have your heat at 87*????

That is *way* too warm -- hot even. Please turn it down to 80* maximum. No wonder they are dying. Not only are they not getting enough O2 because of the temperature, but you're cooking them

Roan

 

[asincero]

WHOA! Why do you have your heat at 87*????

That is *way* too warm -- hot even. Please turn it down to 80* maximum. No wonder they are dying. Not only are they not getting enough O2 because of the temperature, but you're cooking them

Roan

Really? I turned up the heat a while back to handle an ich infestation. The theory being turning up the heat speeds up the ich lifecycle, then filter the water with a diatom filter to remove the parasites. I just never turned it back down ... the fish didn't seem to mind it at all. That is, until I turned off the aeration!

What about the powerhead idea. I'm thinking of buying three of them today from the LFS and strategically position them in the tank to create more circulation. I'm not sure where I should place them yet, though. However, using a bunch of powerheads would be better than using bubbles for a planted tank due to no CO2 dissupation at the surface, no?

 

[Danny-O]

Roan is right--turn down the heat! The warmer the water, the less O2 it can hold. Turn down the heat, and you can keep the bubble curtain off and won't need to mess with additional powerheads (if you have sufficient current to avoid dead spots with your setup as it is now.)

Actually, most vets around this board will tell you use salt to treat ich--heat speeds things up, but is not necessary--but that's a separate subject. Go here:
http://www.aquariacentral.com/forums/showthread.php?t=39759

 

[RanchuRick]

When the ich is gone, turn the heat back down to 80 (or lower). Just curious, I use a XP2 as well. I set up the outlet tube under water to minimize splashing noise. It defintely does not create much surface activities. I also have an Aquaclear 110 which provides all the surface turbulance I need in my 72G. For your 36G the XP2 is enough filtration, but you may still consider a smaller HOB to create the surface turbulance. If you choose to use a power head, I don't think you'll need more than one.

 

[gagaliya]

it's a combination of co2 injection + high temp -> low oxygen + high co2 , and 40-80ppm nitrate!! that killed your fishes. Remember plants do NOT produce oxygen when lights are off. To stop killing your fish:

1) Temp to 80F slowly
2) Assuming you have a diy co2 and cant really stop the co2 injection: Get a coralife power center timer and a powerhead. Put the light on 1 timer and the powerhead on the opposite. So when the lights are on, the powerhead is off since plants are producing all the oxygen and you want to min surface movement so co2 does not escape. Then when lights are off, the powerhead turns on creating surface movement to bring oxygen into the water and let co2 escape to balance out the water params as plants have stopped producing oxygen.

 

[asincero]

it's a combination of co2 injection + high temp -> low oxygen + high co2 , and 40-80ppm nitrate!! that killed your fishes. Remember plants do NOT produce oxygen when lights are off. To stop killing your fish:

1) Temp to 80F slowly
2) Assuming you have a diy co2 and cant really stop the co2 injection: Get a coralife power center timer and a powerhead. Put the light on 1 timer and the powerhead on the opposite. So when the lights are on, the powerhead is off since plants are producing all the oxygen and you want to min surface movement so co2 does not escape. Then when lights are off, the powerhead turns on creating surface movement to bring oxygen into the water and let co2 escape to balance out the water params as plants have stopped producing oxygen.

Err ... slowly? D'oh! In a mad panic after reading Roan's response, I immediately dropped the temperature. My fish probably really hate me now. It's currently at 81. The lights are off at the moment, so it'll probably rise a bit when they come on. I guess I should adjust the heater so it's around 80 when the lights are on, eh?

Just curious ... the plants in my tank seems to be doing ok for the most part, except for the java moss. Which is odd, because java moss is supposed to be really resilent. It looks like it's turning brown. I wonder if this could be related to the heat.

Oh, I'm not using DIY CO2. I used to, but got tired of discarding the funky sugar mix when the CO2 bubbles stopped. I'm going to go pressurized eventually.