# Water Current - Filtration - Too much? Not Enough? (and more).



## zbrendon (Feb 28, 2012)

Hello, 
My girlfriend and I purchased a Top Fin Aquarium kit and stand. The aquarium is 30"W x 12"D x 22"H; 37 Gallon, and it came with a Top Fin Power Filter 40 (supposedly 200 GPH). We have set the aquarium up (2 large ornaments, Black Sand in the bottom). 
We purchased 6 Neon Tetras to cycle the aquarium (not the best fish choice for cycling I now know, but we live and learn). They have been living in the aquarium for just a couple of days now.
I know top fin isn’t the best brand, and I know we will need to add some plants and hiding spots for the fish, but before we get to that I had some more basic questions.
I am having trouble finding information about water flow (Water current) in a freshwater aquarium. 
One of the decorations had an air stone in it, but the air begins about ½ way up the aquarium (It’s a dragon standing on its back legs, spewing bubbles from its mouth). I mention this only to say there are currently no bubblers at the bottom of the tank (nothing down there to help move/stir up the water).
The Top Fin 40 HOB Power Filter creates a fairly significant “Downward Current”, on one side of the tank. So far the Tetras seem to be completely avoiding this “Downward Current” of water… and when they are in the corner of the aquarium (near one of the decorations seeming in a spot that is somewhat sheltered) they seem to be swimming rather hard, just to stay stationary. I’m not sure if this is standard fish behavior, or if they really have to swim hard to stay stationary because of the water flow.
Also, I noticed that one of the fish flakes I fed then the other day is sitting still in the dead center of the aquarium floor, so obviously the current isn’t too intense, otherwise I would think the flake of fish food would move around the bottom of the tank… (Perhaps it’s just next to a raised area of sand, and therefore safe from the current). 
I have been searching and reading for the last 5 hours about water currents in fresh water aquariums, but I’m not finding a lot of information. 
Here are some of my unanswered questions:
1. Is the Downward water current created by a 200 GPH filter too much for small fish (I can turn down the flow rate if necessary)? I would assume that the manufacturer would provide the correct equipment for success in an aquarium “Kit”, but to be honest I don’t have that much faith in most manufacturers….
2. Is the current produced by the filter insufficient to reach all areas of the tank (30"W x 12"D x 22"H)?
3. The part of the HOB power filter that is in the water (I don’t know the technical name), is 6-8” from the bottom of the aquarium. Does this need to be extended farther down to the bottom of the aquarium, or id it fine there (I don’t know If there is current on the bottom of the tank)?
4. Because there is a flake of fish food sitting, unmoving in the center of the tank it makes me think there is little water movement there. Do I need some kind of power head or submersible pump down there to create more water circulation? If so how much is enough, and how much is too much?
5. Is my HOB filter which sits on one side of the tank enough to circulate the entire contents of the aquarium? I was considering purchasing another 200 GPH filter and placing it on the other back corner of the aquarium, and putting BOTH filters at about ½ power. In my mind that would eliminate the excessive “down” current, circulate water from multiple areas of the tank at once, and not cut down on the overall water cycling capability. Is that a dumb idea?
6. A HOB filter seems to deposit the water back into the aquarium right by the water inlet (Again, I don’t know the technical name for this thing). Am I just re-filtering the same water over and over again?
7. Watching YouTube videos of people’s aquariums it seems some people with the HOB filters have then cranked way up (Lots of water movement), and others seem to have them cranked way down (Little water movement). I have also seen “MODS” of people redirecting the flow (using a plastic cup so water enters the aquarium away from the water inlet to answer question #6 above), or putting a sponge in the exit path of the filter (to lower the turbulence or “Downward” current). If any of this necessary, or recommended? 
8. Any other advice anyone had would be welcome! 
I know “Different fish have different requirements”. There are some of the things I am considering putting in the tank (eventually… once cycling has completed, and I am confident about my other issues) Hammers Cobalt Blue Lobster (Procambarus clarkii) , Freshwater Clam (Corbicual sp.), Singapore Flower Shrimp (Atyopsis moluccensis), GloFish® (Danio rerio) (assorted 6 pack), Cobra Guppy (Green or blue), Panda Oranda Goldfish (Carassius auratus), Hi Fin Lyretail Swordtail (Xiphophorus helleri), Harlequin Rasbora (Rasbora heteromorpha), Black Veil Angel (Pterophyllum sp.), Albino Aeneus Cory Cat (Corydoras aeneus)… The list may change, and I don’t think I would get ALL of those species, that’s just to give an idea of what kind of fish I am considering.
Thank you!!!


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## ladayen (Jun 21, 2011)

Ok so what you have is a 35g Tall tank.

No fish are neccessary to cycle a tank. Simply throwing in a few flakes every couple days will do the job.

Neon tetras dont like currents so if you can turn the filter down I would suggest doing that. 200gph is fine for the tank you have. Few fish of that fit your size tank will need a stronger current.
The best spot for the intake part of a filter is about 3-4" from the substrate. If you can lower it easily go ahead but dont try to force it. I have a similar tank and I dont think my filter was nearly that strong. It was more then enough for the tank. You dont need any further powerheads or what not.
MODS are used when a high filtration rate is necessary but the resulting current is not desireable. Directing the flow back against the glass acts as a buffer to "dumb" the current a bit. Goldfish would be an example where you might want this.

As to your list of species your interested in.. I would say no to the goldfish and lobster right off the bat. To further provide advice I would need the PH for sure, hardness(GH, KH) if possible.


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## Byron (Mar 7, 2009)

I second ladayen's post, and will just expand a bit on your question of suitable water flow.

Filtration and water flow are two different things, though related. Taking just the flow issue, fish have different needs and their long-term health is rather dependent upon this. Fish have evolved naturally to suit their respective environment and habitat, and providing this in the aquarium is crucial if they are to be free of additional stress which weakens their immune system at the very least, causing more health issues.

Most of the fish you list are what I term forest fish; they occur in slow-flowing streams, lagoons and flooded forest habitats. For such fish, having to continually fight a strong current simply wears them down faster. Think of it as you having to continually--day and night--walking up a steep hill. It takes more energy, which means more food, more oxygen, a higher metabolism, with no "rest." The fish in the aquarium are forced to endure whatever we give them, they have no escape as they might in nature.

Water flow that is sufficient to ensure a continual movement throughout the aquarium is sufficient for such fish. Speaking of which, you have some non-compatible species listed. And compatibility means having the same requirements respecting water flow, light, temperature, pH and hardness, environment--wood, rock, plants, sand, gravel...--and so forth. You might find our profiles useful; second tab fro the left in the blue bar across the top. If the scientific or common name used in the profile is used in a post it will shade and you can click that for the profile, example Harlequin Rasbora or Pterophyllum scalare. Info on the fish's natural habitat is included, along with aquarium aquascaping suggestions if these are relevant, water parameters, tank size, numbers (some fish are shoaling and need a group), etc.

Hope this is of some help. And welcome to Tropical Fish Keeping forum.:-D

Byron.


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## zbrendon (Feb 28, 2012)

As far as my fish selection, as i mentioned above, that list is just "potential" fish. I have a spreadsheet going that tracks the requirements of each fish I am considering (it's got Ph, temp, diet, water hardness, adult fish size, temperament, etc). I will be extremely conscientious of the environment they are in, how they will get along, etc. I will be sure that my final fish selection and aquarium setup will the something that both the _fish and I_ will be happy with. 

Now, if i can just figure out what filter I want to use (I purchased a Magnum H.O.T. 250 last night, but I couldn't get the stupid thing to work correctly). 

Thank you for your advice and opinions!


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## TwinDad (Mar 3, 2011)

I have had good luck with the Agua Clear Hang on back filters. Quite (for a HOB) and you can adjust the flow rate if you feel it to be too strong. The filter media is relatively cheap and you can customize it a bit if you choose. I put the large mechanical filter material in the bottom of mine, followed by a sponge, then fine filter floss. I had bio media in mine until I planted the tank.

Check out the AC30 or AC50.


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## AbbeysDad (Mar 28, 2011)

TwinDad said:


> I have had good luck with the Agua Clear Hang on back filters. Quite (for a HOB) and you can adjust the flow rate if you feel it to be too strong. The filter media is relatively cheap and you can customize it a bit if you choose. I put the large mechanical filter material in the bottom of mine, followed by a sponge, then fine filter floss. I had bio media in mine until I planted the tank.
> 
> Check out the AC30 or AC50.


"Large mechanical filter media"??? No such thing. The sponge should be first, followed by optional activated carbon, followed by bio-max ceramic media, followed by filter floss as/if desired. ;-)


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## TwinDad (Mar 3, 2011)

AbbeysDad said:


> "Large mechanical filter media"??? No such thing. The sponge should be first, followed by optional activated carbon, followed by bio-max ceramic media, followed by filter floss as/if desired. ;-)


I'd need to find it again but it was basically ceramic noodles that get the large particles out, then the sponge. I had read something in a guide that was posted. I have been for months thinking of taking it out as it rarely has debris large enough stuck in it while the sponge got everything.

Still thanks for the advice.


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## Maxillius (Sep 27, 2011)

I use a fluval c3 and im very impressed with it , you can change all the medias for diy medias or anything you want!
I used the sponge i got from it since the start I just rince it then i replaced the carbon with a bag of purigen!
and the wet dry trickle system is good! even tho small the c-nodes for it are very porous!
its very easily washable everything comes apart easily and is placed back together in a matter of seconds!
it is also very very quiet in order to hear anything from it aside from water trickle i have to close down everything in my room*computer, air pump and fan on my light* and get my ear close to it then If i lisent very carefully I might hear a little bit of the motor!


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## Grimmjow (Jul 22, 2009)

Byron said:


> Most of the fish you list are what I term forest fish; they occur in slow-flowing streams, lagoons and flooded forest habitats. For such fish, having to continually fight a strong current simply wears them down faster. Think of it as you having to continually--day and night--walking up a steep hill. It takes more energy, which means more food, more oxygen, a higher metabolism, with no "rest." The fish in the aquarium are forced to endure whatever we give them, they have no escape as they might in nature.


Is the reverse of this true too? Like if I want something that likes current but I don't like a lot of current, would that be bad for them?


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## Byron (Mar 7, 2009)

Grimmjow said:


> Is the reverse of this true too? Like if I want something that likes current but I don't like a lot of current, would that be bad for them?


Yes. Fish from fast-flowing streams must be able to have a reasonable water current in the tank or they can be stressed. In some cases, it causes a lack of oxygen because the fish is programmed to live in oxygen-rich water (fast flowing water is generally higher in oxygen than still water due to the gaseous exchange). Putting Hillstream Loaches in a tank with little or no water movement for instance would soon cause them distress and they would very likely die.

I have a trio of Centromochlus perugiae in my 115g. Knowing they need currents, I have the Rena XP3 filter return at one end of the tank but without the spraybar, so I get the direct force of the water return, and it is directed into the end wall of the tank from about a foot down the tank. When I moved these fish into this tank, they were in a chunk of wood which I placed at the opposite end of the tank. Within a day all three had taken up residence in the wood right in front of the filter return. They wanted and need the current.

This is one important aspect of establishing a "community" aquarium; the fish must all share similar needs respecting water flow as well as light and other environmental factors. Sometimes a bit of compromise is possible, as in this tank; the flow is strong at that end, but weakens as it hits the wall and travels down the 5-foot tank. Not surprisingly, the forest fish remain in the opposite half of the tank where the current is less. With sufficiently large tanks one can provide this sort of compromise and the fish can stay where they prefer. In smaller tanks this is not feasible, so it must be one or the other.


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