are your fish getting enough oxygen?

[Sk8r]

If a fish is hovering near a water flow or near the surface, it may need more oxygen. If it grows listless, same thing.

Ich can cause this behavior, by affecting oxygen intake by the gills; but very, very often the tank is just oxygen-short.

Tangs and angels need more than most aquarium fish: they're like jet engines, consuming it like crazy. Those species will 'complain' first, or may mysteriously start to fail...another very good reason not to stock tangs in a small tank.

Over-warm water contains less oxygen. 80 is a good mean temperature to stay to.

Everybody knows that plants give off oxygen and absorb co2. But did you know that they do the reverse after the lights go out? At night they suck oxygen out of the water and give off co2. A really dense algae growth can do more than look bad: it can hurt your fish.

To increase oxygen, increase flow. Your tank may need a second pump. It does not need a lid anywhere in the system. Let it breathe. If you have jumpers, take measures like a high riser or eggcrate.

HTH.

 

[essexboy73]

i have been having a problem with high CO2 levels in my tank which contributed to a low PH...since its summer the house has been closed up for a few months and i think that the CO2 levels are alittle high....once i started opening my window, that is behind the tank, for about an hour a day everything has been back to normal.....things looked really bad for about two weeks...

 

[sir_dudeguy]

I think that you did a great job on that sk8r. Very helpful. I sure learned a few new things

essexboy...do you have a glass hood, or some other hood that doesnt allow for very much air over the tank? if so, try taking that off, because they dont allow for proper gas exchange, which would be why you have the c02 and pH problem...get gas exchange to get out the c02, and when that leaves, i believe the pH goes up.

 

[techreef]

Thanks Sk8r! Can you tell me why/how plants reverse their cycle during the nighttime? I understand photosynthesis, but don't get how things reverse.

Essexboy, another low pH cause to consider is if you were cycling new LR over the summer. I believe that the process is acidic in nature, and will depress your pH. My pH was low, but is now in the healthy 8 range. But I also have a month-old tank, so it may be fluctuating due to some other unknown variable. So many possibilities! Sheesh.

 

[Shagsbeard]

I've never heard that 'reverse' either... can you site a reference?

 

[SeanySean]

During the night, plants consume oxygen and give out CO2 land plants do it as well

 

[Travis L. Stevens]

It's called "Dark Respiration". A simple google search yields TONS of results.

 

[Sk8r]

The flip side of the cycle used to be a big problem in freshwater tanks before the advent of bigger pumps: people would grow a LOT of weed thinking it meant high oxygen and then have mysterious fish losses at night, particularly of angels, which have, again, a pretty high oxygen need compared to other common freshwater fish. People who find saltwater fish dead in the morning often blame lurkers in the rocks, but the cause may lie in low flow and possibly too much weed in the system---for that level of flow. I'm not sure how refugiums factor into this, but if *all* the tank water goes through a refugium during its cycle, and the refugium were quite large and choked with weed---well, that may be needless worry: I think ordinarily the relationship of a refugium to the display and sump is so small as to be negligible in this regard.

 

[SeanySean]

refugiums , normally have a reverse lighting period