oxygen ... or lack there of

[logan5]

I have a heavily planted tank with CO2 injection.  Because of that, I try as best as possible not to disturb the surface so as to keep as much CO2 in the water, however, this being post HAS auction and my wife having purchase a bunch of new fish dispite the fact that we didn't (at the time) have a second tank, I now find my self in a spot of trouble.... my fish are breathing heavy and coming to the surface to breathe.

Needless to say that was alarming, so i went to the LHS and got me an airpump with a stone and have since put it into the tank, and the fish are doing better.  This being the situation untill the new tank is cycled, I'm wondering ... what impact to my plants will this be?  How much CO2 will I be losing?

Anythoughts of a better way to have handled this problem?

Just for info, my return tube is pluged directly into my intank CO2 reactor, so no spray bar.

Thanks
logan5

[PhishPhreek]

Re: oxygen ... or lack there of

I took gas dynamicks over 35 years ago and I'm operating from memory so any of you younger engineers are welcome to correct me.

The air pressure in the water wants to be the same as the air pressure outside.  Thats one of the reasons you get bubbles when the water comes out of the faucet.
Each separate gas works the same.   The partial pressure of O2 wants to be the same on both sides of the surface and the partial pressure of CO2 wants to be the same on both sides.  They don't really care what the partial pressure of the other gas is.

The surface area controls how fast the gas migrated from the high side to the low side.  So when you circulate the water on the surface with a pump or an airstone, you are increasing the surface area and the gas migrates faster.   Its been a long time since I took the course so I can't calculate how much is being transfered.  Also rember that the plants are using CO2 and giving off O2 while the fish are using O2 and giving off CO2  which also contributes to the partial gas pressures in the tank.   So if you want more O2 you can add more plants.

[Tiapan]

Re: oxygen ... or lack there of

i agree tha tmore plants would not be a bad idea, the other option i have heard from those that use heavier amounts of co2 is that they turn off the co2 at night since the plants are not converting with light at that point and then they turn on the air pump to make up for the o2 that the plants are no longer producing. the safest bet by my reasoning would just be tank off the co2 till you have the other tank running well and cycles. if you take water from your established tank and a bit of its gravel or its old filter catridge you will be almost completly cycled(especially with old filter) plants in the new tank again not a problem at all, that way yu can get the fish moved sooner rather then later cause fewer problems then.

[Ellen]

Re: oxygen ... or lack there of

So you got the new tank for the fish and you don't want them in your established planted tank?

If you can do like Tiapan said and take some of your filter media and stick it in the filter of the new tank, you can almost skip your cycle. In fact, sometimes it doesn't even register if you have enough bacteria in your material and a low enough stocking rate. I disagree about the water though, I feel moving dirty water is just moving dirty water. It doesn't hold nitrifying bacteria, and if you are fertilizing your planted tank and not your new tank, your extra ferts can make a big old algae bloom, which nobody likes. If you can't move your filter media, you can take a scoop of gravel and stick it in some pantyhose and stick that in the filter along with the filter media. That also helps seed the filter to help things along.

On anther note, I've read about fish just not being used to the CO2 in the tank. Because having more CO2 does not displace the 02 in the aquarium, they still have plenty of O2 to breathe, they're just not used to also having CO2. I have read success when people turned down their CO2 in the tank and then gradually raised it over a couple of days. (I don't know anything about this first-hand, but I have read it several places.) Do you use ferts and high light? I would think that if you do, without the CO2 you might experience an algae bloom, so you might not want to light the tank while you're doing this. This solution seems like a good idea because its just a matter of days until you have your CO2 back up, and the fish 'learn' how to cope with the CO2.

HTH,
Ellen

[logan5]

Re: oxygen ... or lack there of

It's not that I don't want them in my planted tank ...  it's just that the tank is way over stocked ... I have to do a water change pretty much every other day and am considering adding a HOB filter to help my eheim with the added bio-load.

I'm going to give bio-spira a try if I can get my hands on it, but thill then ... i'm just stuck with one tank.

Oh, during the day time with the plants producing O2, the fish don't seem to have a breathing problem ... only at night and morning, so that's when i turn on the airpump.  This apparently is a popular setup.

Logan5

[Mzungu]

Re: oxygen ... or lack there of

Yes, a lot of people do just that. I don't think you need to turn off the CO2 at night if you're also turning on the air pump. It's been said that CO2 at night, when plants AND fish are both producing it, really has a negligible impact on the fish. But, if you're seeing the problems at night and in the morning, (especially with an overstocked tank) then I'd continue to use the air pump during those times.

How are you going to cycle the new tank? Like everyone else was saying, it's a great idea to use media from this tank, it's almost an instant cycle, and no need to buy any cycling products. I have heard good things about biospira, but in my opinion, if you have the jump start already, why spend money on more?

What Ellen said is interesting, I've never heard of that before, but it makes sense.  :)  Are the fish with the breathing problems the new fish, or is everyone basically having difficulties?

[logan5]

Re: oxygen ... or lack there of

All the fish were suffering.  Just too many fish in one tank is all.

It is about time for me to do maintenance on my Eheim, I'll just take some of the ceramic tubes and put them in the new filter.

Logan5

[wesleydnunder]

Re: oxygen ... or lack there of

Is there a specific reason you want your co2 on at night, Logan? Jusy curious.

Mark

[logan5]

Re: oxygen ... or lack there of

no reason, just no real way to turn it off at night.

Logan5

[wesleydnunder]

Re: oxygen ... or lack there of

Oh. Are you using DIY or pressurized?

Mark

[logan5]

Re: oxygen ... or lack there of

DIY, also have a DIY reactor where I mix the CO2 with the return water.

Would love to have a pressurized system but it's just too expensive.

Logan5