Tropical Fish Keeping - Aquarium fish care and resources

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-   -   **Water Filtration Question** (http://www.tropicalfishkeeping.com/beginner-freshwater-aquarium/water-filtration-question-104305/)

neonk 06-14-2012 10:05 PM

**Water Filtration Question**
 
I was wondering if water from a filter needs to acually "ripple" or create a disturbance to properly oxygenate the water. Reason I'm asking is because I just set up a new aqueon 5 gallon mini-bow tank. There is no water fill line. When you fill the water to the top of the tank, you can see water pour over the filter but there is no big disturbance to the water. This is a type of filter that actually sits into an irremovable holder on top of the tank, the water then pours over a filter that lays flat. This is a little different than the normal filters where the water pushes sideways and then is forced out of the top.
This setup runs very quietly but my question is, is the water movement that the filter releases slightly below the surface enough or should I not fill the water to the top. There are really no instructions, maybe someone can help out.:-P

LyzzaRyzz 06-15-2012 12:05 AM

I am almost positive that there needs to be a ripple, or bubbles of some sort.
Though i used to have a filter that had bubbles behind the filter matter, but they didnt go beyond that. The water flowed silently, and without disturbance. Since there was bubbles, the water was oxygenated.

Im not exactly sure what type of filter you are talking about? Do you have a picture? or a link?

equatics 06-15-2012 02:07 AM

I've just been reading a rather long thread in a forum on this subject. My take (and what I learned and agreed with) is that in a tank in which you have no plants or they're not your focus, surface agitation is good for oxygenation because the atmospheric interface is expanded, getting more surface area for oxygen to get into the water.

For natural planted tanks (without injected CO2) I seriously think that surface agitation is to be kept at a minimum so that the CO2 will escape from the water at the slowest rate possible. I am thinking I should get rid of my hang-on-back filter and get a canister filter with a spray bar positioned not to create surface agitation. Don't put so much water in the tank that there's not enough air! Good luck!

AbbeysDad 06-15-2012 08:18 AM

There is always some gas exchange at/on the surface of the water. Carbon dioxide (CO2) is exchanged for oxygen (O2). The exchange is greater with surface movement, turbulence or waterfall like disturbance.
An air pump and air stone does not put oxygen into the water, but the oxygenation happens when the bubbles break the surface and CO2 is exchanged for O2.

Water circulation is very important. Surface turbulence requirements vary to have sufficiently oxygenated water.

Geomancer 06-15-2012 08:25 AM

I think all that's required is the surface tension to be broken.

However, it's easy enough to tell if your fish are getting enouch oxygen. If they do not have enough, they'll hover at the surface gasping, that's the sign you need more agitation.

equatics 06-15-2012 08:50 AM

I've got a sort of question related to this discussion. For purpses of this question, let's assume that at night in a low tech tank with the hang-on-back filter off less surface agitation would keep CO2 longer in the water more at night. I assume that photosynthesis during the day would be able to proceed longer without surface agitation during the night.

I have a hang-on-back filter which creates plenty of surface action. I would like to turn off the HOB at night. I figure that since the fish are less active at night and use less oxygen they'll be alright. Will the results be significant enough to warrant the change? Will the stagnancy at night work negatively?

Appreciate any analysis.

neonk 06-15-2012 03:37 PM

Pictures of filter and tank
 
2 Attachment(s)
As you can see, water pours over the top of the flat laying filter and then goes back "underwater" into the tank itself. The more water is in the tank, the better it is distributed over the filter. When water is lower it covers about a .25 cents piece of the filter. So it must be ok to have the water high. The agitiation of the water must be coming from where the water pours in not where it is released because that is submerged. Pretty weak flow coming in though, guess I'll find out when cycling is done and I add fish if there is enough oxygen or not.

equatics 06-15-2012 04:27 PM

Looks like if you want to grow a nice low-tech planted tank, you won't have any surface agitation. If you really want some you can buy an air pump and some kind of bubling device.

In any case, the output from the filter should be moving the water to the surface, making it available for oxygenation from the oxygen interface which is the surface of the water. I would check the filter output and see if it's adjustable.

About the water height - I fill mine to 1/2" below the top. Remember - at some time you're going to have to put two arms into the tank, or one anyway.

Byron 06-15-2012 06:19 PM

Quote:

Originally Posted by Nemo the Clownfish (Post 1117208)
I've got a sort of question related to this discussion. For purpses of this question, let's assume that at night in a low tech tank with the hang-on-back filter off less surface agitation would keep CO2 longer in the water more at night. I assume that photosynthesis during the day would be able to proceed longer without surface agitation during the night.

I have a hang-on-back filter which creates plenty of surface action. I would like to turn off the HOB at night. I figure that since the fish are less active at night and use less oxygen they'll be alright. Will the results be significant enough to warrant the change? Will the stagnancy at night work negatively?

Appreciate any analysis.

You should never turn off the main filter, at any time. Bacteria in the filter need oxygen, and stopping the water flow for more than an hour or two (as when doing a water change) will suffocate the anaerobic bacteria. Depending upon the fish in the tank, this could harm them too, in a couple of ways.

Filtration and water flow are two very different things, though they obviously are connected since both are normally due to the filter.

In a balanced natural-method planted tank, there will never be any shortage of oxygen or excess of CO2 that will cause any issue for fish.

CO2 definitely builds up during darkness, otherwise the natural or low-tech method wouldn't work at all. In most natural planted tanks, the CO2 will basically be used up during the light period, so it has to be replenished during darkness. And keeping surface disturbance minimal will prevent it from being driven out of the water faster.

LyzzaRyzz 06-15-2012 08:26 PM

Ive actually never seen a filter like that neonk!
Does it float on the surface, or is it suction cupped?
maybe raising it a bit off the water would help with helping oxygen enter the water?

What do you think Byron?
Ive never encountered this type of filter before..so i dont know how to fix the problem!


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