How much surface agitation is required and why?

[Mitchell_UK]

I understand the requirement for good water movement around the display tank but how important is surface agitation?

My system is a little different from a traditional setup in that the display tank has no equipment in it and nothing breaks the water's surface. The water is cycled to the sump via a bottom drain therefore I don't surface skim in the display.

I'm currently playing with the flow around the display tank and unlike previous setups when I had a power head disrupting the water surface sometimes violently I can have substantial water movement but with little agitation of the surface.

The reduced agitation appeals to me as I like to look down into the system and if the surface is calmer then I can see in better. I'm aware of the surface providing gaseous exchange and the agitation helping prevent a film on the water surface but my question is how much agitation is required?

I can agitate the water surface in the sump to a greater degree if this would help the system as a whole but I was unsure if the PH of the sump volume would buffer the PH of the display tank or vice versa, the tanks are in different rooms.

Any thoughts or pointers to relevant articles would be appreciated.

Thank you

 

[Prestigious]

You bottom drain??? This sounds a bit dangerous from a flood persepctive. Also, there have been tons of articles in regards to the benefits of surface skimming.

Surface agitation is the best way to get oxygen into the water (next to skimmers). Larger fish require larger amounts of oxygen in the water, so be careful. I get oxygen in my tank from my skimmer (which is connected to my sump) and surface agitation from my return lines from the return pump. This sounds great, but I recently had the pump get clogged while at work which drastically dropped the oxygen in my tank, killing my 2 largest fish before I made it home. With the return pump down, not only was I not getting surface agitation BUT I also wasnt getting the nice oxygen rich water from my skimmer back up into the display.

Just something to think about, feel free to learn from my mistakes.

 

[Mitchell_UK]

You bottom drain??? This sounds a bit dangerous from a flood persepctive. Also, there have been tons of articles in regards to the benefits of surface skimming.

Surface agitation is the best way to get oxygen into the water (next to skimmers). Larger fish require larger amounts of oxygen in the water, so be careful. I get oxygen in my tank from my skimmer (which is connected to my sump) and surface agitation from my return lines from the return pump. This sounds great, but I recently had the pump get clogged while at work which drastically dropped the oxygen in my tank, killing my 2 largest fish before I made it home. With the return pump down, not only was I not getting surface agitation BUT I also wasnt getting the nice oxygen rich water from my skimmer back up into the display.

Just something to think about, feel free to learn from my mistakes.

My display tank is linked to another tank which is at the same level, water circulates between the two tanks via three gravity drains. The second tank is then linked to a sump in the traditional way. Water can't escape from the two tanks as they operate like a closed loop.

I understand that surface agitation helps gaseous exchange but how much agitation is required for an efficient exchange to take place?

I guess I'm going to have to play with a ph probe and measure O2 levels unless anyone has any calculations or suggestions?

 

[ReeferBatman]

Depends on your bio-load. More creatures use more oxygen. Surface agitation is best to promote that gas exchange.

If you notice fish hanging near the surface, or kinda 'gasping'... then you know for sure you need more.

If everything seems happy and healthy then you should be good.

 

[MellowReefer]

Good topic I've been thinking about after hearing stories like that above. My acrylic tank is almost totally sealed except the holes for wires, but my sump is open. But I worry what would happen if the return pump failed.

Every once in a while I notice my royal gramma opening its mouth really wide. And I have seen my cardinal and firefish do it occasionally. This isn't a symptom of low oxygen, is it? My clowns sometimes hang out near the top but other fish don't.

 

[coralreefdoc]

No, that isn't an O2 deprivation symptom from your Gramma loreto ... Rather, a territorial display, characteristic of the Royal Gramma and its relative Genus Liopropoma (Reef Basslets)

 

[fjpod]

take a small amount of water, maybe a liter, from your display tank and put it into a container. measure the ph. then aerate it with a simple airstone outside where the air is fresh and O2 is higher. After about an hour, measure the ph again. If it is more than .5 units higher with outside air, you probably need more surface agitation.