Filter Flow Rate & Angelfish

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tywright19

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Hi everyone,
I have a 30 (ish) gallon tank, measuring 100x30x40cm, but am currently struggling to understand how to properly circulate the water.
I have read and been told numerous times that the filter should have an output per hour that is at least 5 times the volume of the tank (ideally more), so I bought a Fluval U4 internal filter. According to their website, the filter has an output of 260g per hour, which is just over 8 times my volume, so I assumed it would be perfect.
However, the flow rate seems a bit too strong for my Angelfish, and he seems to just hover in one section of the tank, rather than swimming around the middle like he used to.

So what do I do?
I would think the obvious thing to do would be to reduce the output flow, but if I do that, wouldn't that reduce tank circulation?

Any help would be greatly appreciated as I am currently very confused on what to do.
 
There is a fair amount of misunderstanding in the hobby concerning filtration. The fish species in the tank should always be the priority. Provided the tank is not overstocked, and provided the species are "compatible" (which has a lot more to it than just behaviours), there really is no need for a filter at all. Once you understand that, it is easy to see that we frequently go overboard, and usually to the detriment of the fish. The myth "you can't have too much filtration" is not only wrong, but dangerous.

Angelfish are sedate shoaling fish that cruise more than actively swim. Such species almost always occur in still water (lakes, ponds, swamps) or slow-flowing streams. If they are found in rivers, they tend to be along the shore where the current is much less than it is in midstream. This is one reason why researching and understanding the habitat of a species is so critical to its long-term health. Forcing such a fish to exist in strong currents will wear it out, cause stress which weakens the immune system and allows for disease to take hold, and result in a shorter than normal lifespan as a result. The fish's metabolism and physiology are intended to function in very specific environments.

My two 29g tanks (which I will assume are probably close to your 30g in dimensions) each have a dual sponge filter; I have the same filter in my 40g tank, and my 33g has a small internal filter that is nothing more than a sponge (foam) with a small motor. This provides sufficient water movement to maintain clear water by removing the microscopic suspended particulate matter. That is all you really need in a filter, mechanical filtration. Biological filtration will naturally occur on the sponges, and elsewhere (the substrate is your primary site for all bacteria). A biologically balanced tank will need nothing more, unless you have fish that require a stronger current obviously.

I assume you only have the one angelfish, as you couldn't fit more in this small a tank. And provided you have similarly sedate fish, and not many, you don't need so much water flow. If you can reduce it, I would do so. There are other ways to achieve this too, such as placing the filter return behind a large chunk of wood (or rock) to dissipate the flow, or if it has a spray bar direct the holes into and down the end glass. You can usually achieve some surface disturbance and this is important; you just don't want a current throughout the tank that is sufficient to make the fish struggle against it.

Byron.
 
I will admit, the tank is quite heavily stocked.
I also have a small pike cichlid in there, along with a small Senegal Bichir. However, I plan on upgrading to a 70 gallon in a few months so this setup is only temporary. Nevertheless, I want to make sure my filtration and circulation is adequate in the meantime.

The filter is not designed in a way that would allow me to attach a spray bar, but I can turn down the flow.
What exactly is the goal in terms of circulation though?
Should the flow from the filter reach the other end of the tank? If not now do I avoid "dead spots" where there is no circulation?

Thanks,

Tyler
 
"Dead spots" are the very least of your problems. The problem now is you have completely non-compatible species and in a too small space given that incompatibility. But the filtration isn't really a factor in that-- more frequent and largish water changes are beneficial as these remove the pheromones and allomones along with everything else that filtration cannot begin to handle.

"Dead spots" is something I have never worried about. They really don't exist, in the way some people might think. I mentioned earlier about no filter, and I had a 10g running for a year with no filter. The fish were suited to the space, and each other (pygmy cories, dwarf rasbora) and there were plants thriving. In my other tanks, with filters, if I stick my hand in during the water change to trim plants or something, the water at the substrate is considerably colder than at the surface. The fish don't seem to care, and this does occur in nature anyway. There are also natural currents created by fish movement;, decomposition heats the water in the substrate so it rises up into the tank and cold water seeps down. Thermal currents.

It is also possible to have too much water flow through the filter such that nitrification is actually impeded. The bacteria need time to grab the ammonia and nitrite.

The stress caused to the fish by all of this is another concern; the fish are being weakened and this is irreversible.
 
The fish are not yet fully grown.
The angelfish is about 4 inches and the pike and Bichir are about 6. I should point out that the pike is a Crenicichla Lucius which from what I've read, maxes out at around 6-8 inches. I agree with you that the tank is too small for them in the long term which is why I am upgrading to a larger tank, but in the meantime, they seem to be getting along perfectly fine, and I have no issues with aggression.

In terms of water changes, I am currently doing 2-4 20% changes per week. I find it hard to read the results of my liquid test kit, as I am partially colour blind, but I believe that nitrates are most often around 20ppm. Do you think this is adequate, or do you think I should be doing more?

Thanks for the advice on the filter flow. There are so many differing opinions regarding filtration that I often find it hard to determine what is true and what isn't. So just to clarify, I can reduce the flow of my filter with no ill effects on the tank?

Also, I noticed you mentioned about removing pheromones from the water. Could you please explain what you mean by this as I have never heard about it before.

Thanks,

Tyler
 
I will respond, not to be argumentative, but because there are less experienced members who read these threads and can take away the wrong impression if things are not fully explained. So with that in mind, I must comment on your first paragraph.

The fish are not yet fully grown.
The angelfish is about 4 inches and the pike and Bichir are about 6. I should point out that the pike is a Crenicichla Lucius which from what I've read, maxes out at around 6-8 inches. I agree with you that the tank is too small for them in the long term which is why I am upgrading to a larger tank, but in the meantime, they seem to be getting along perfectly fine, and I have no issues with aggression.

You cannot possibly know this, any more than I could. There doesn't have to be physical interaction to demonstrate aggression, it can be "silent." This brings us to your question to explain pheromones.

Fish communicate by chemical signals as well as visual and hearing. Fish release pheromones that can be read by other fish in that species. Allomones are released and read by other species. Fish use these to express aggression, submission, the presence of food, danger, spawning desire, etc. They are in the water and can only be removed by water changes. They are strong enough to be "read" in the habitat waters, so imagine their effect within the confines of an aquarium. It is possible to severely debilitate a fish to the point of death solely by means of these chemical signals. Think of it as putting a cat into a closed room in which a vicious dog is chained in one corner. The dog cannot reach the cat, but the cat doesn't know that, and will be terrified. So too these fish; they are severely weakened.

In terms of water changes, I am currently doing 2-4 20% changes per week. I find it hard to read the results of my liquid test kit, as I am partially colour blind, but I believe that nitrates are most often around 20ppm. Do you think this is adequate, or do you think I should be doing more?

I would increase significantly the volume of each change. I do a weekly change of 50-60% in all my tanks, and I would not do less than at least 50% here. I am assuming the parameters of the tap water are close to those of the tank water, so this should be no problem; you really cannot change too much water. [Parameters being GH, KH, pH and temperature.]

Nitrates should be as low as possible; these are toxic to fish, and cichlids are especially vulnerable. At 20 ppm, you are at the highest it should ever be, but is this consistent, or just before water changes? Some think water changes should be based on test results, so when nitrate increases, time for a WC. That is too late, the damage is already occurring. Water changes should keep nitrates very low, and stable water quality. My tanks run between 0 and 5 ppm, and have been this for years. I don't test nitrate very much, usually only if I see something not quite right, as an initial test. I check pH more often, though this too can be weeks apart, but for well over many months, the pH in each tank has never varied by more than a couple decimal places.

So just to clarify, I can reduce the flow of my filter with no ill effects on the tank?

I don't want to answer this "yes" as there are factors here that are the exception, or should be seen as such. I believe the fish species are non-compatible and thus the biological system is being impacted more, which in turn impacts the fish that much more. I would want to resolve this as soon as possible. Picking up an earlier point, you may think the fish are not out-growing the tank, but I would suggest they are do just that. Fish develop externally and internally for most of their lives, so the water volume as well as the physical space around them from fry on up is extremely critical. The external physical development can be separate from the internal organ development, and this is always debilitating, in extreme cases leading to stunting. The first impact of any of this is stress, and stress weakens the fish's immune system; 95% of all fish disease is directly due to stress. If the stress does not abate fairly quickly, it is irreversible. The fish will be more susceptible to disease, and will in all cases have a shorter lifespan.

Hope this helps, don't hesitate to question anything. B.
 
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The stuff you mentioned about pheromones is really interesting so thanks very much for sharing that info.
Is there any visual way of determining aggression then? The fish do not seem to cower from one another or flare up so I always assumed that they were compatible. Will upgrading to a 70g tank help reduce this issue or is that still not big enough?

I will increase the water change schedule as you recommended. I had always assumed that it was better to do little and often, rather than large changes all at once, but I'll take your word for it.
 
I will increase the water change schedule as you recommended. I had always assumed that it was better to do little and often, rather than large changes all at once, but I'll take your word for it.

Water changes are used to remove pollution, what one writer called "crud," from the system. In an article in TFH a few years back, the author had mathematical data which can be summarized: a 70% water change once a week (at one time) will be more effective at removing crud than will a daily change of 10%. The latter is basically useless. The water change removes a portion of the crud, relative to the complete volume. So changing 10% will remove 10% of the crud, leave 90%. Crud continues to accumulate of course, so next day there is the 90% plus the new crud, and doing a 10% change removes 10% of the total crud. At this rate, the crud is not really diminishing over time. Whereas doing a 70% once will eliminate 70% of the crud.

Some discus breeders change 95% of the tank volume once, twice, some three times a day, in their fry tanks. The improved growth and health of the fry is amazing. And they are able to house more fry in a given tank. As I said previously, you really cannot change too much water, provided the parameters are basically the same.

Is there any visual way of determining aggression then? The fish do not seem to cower from one another or flare up so I always assumed that they were compatible. Will upgrading to a 70g tank help reduce this issue or is that still not big enough?

Sometimes we can see aggression, sometimes not. The wisest will research a species to learn their normal traits and behaviours, and then assume these will hold for any fish of that species. Individual fish can differ from the norm, for various reasons. Sometimes environmental factors affect fish like this (inappropriate tank space, insufficient numbers for a shoaling species, inappropriate aquascape, inappropriate water parameters--all these and other factors can affect fish. Aggression is the usual fish response to unfavourable conditions and stress (stress always occurs from the unfavourable conditions, but also from other factors), but sometimes the opposite may occur where the fish becomes withdrawn and slowly weakens to death. A scientific study a couple of years ago found that too few fish in a shoaling species always increased the individual fish's aggression; somewhat aggressive fish (like angelfish) became markedly more aggressive, and usually peaceful fish (black neon tetra) became aggressive. All due to having too few in the tank. The study noted that the tank volume also factors into this with the same results if the tank space is too small to the fish's perception. Biological and chemical reactions in the fish obviously played into this too.

As an angelfish began this thread discussion, let's use that species, Pterophyllum scalare. We can learn a few things if we observe this fish in its natural habitats. They live in shoals that are, by comparison to fish like Corydoras, small, in swamps and flooded forest where vegetation is thick, and in slow-flowing streams where they remain close to the banks around aquatic plants, roots, branches and/or overhanging vegetation. The light is quite dim. There are no predators in the sense that we might think. So as soon as you introduce an angelfish to an aquarium, on its own, you immediately put the fish into a situation that is completely opposite to what it "expects." Programmed into the species DNA are "expectations" relating to its environment and others of the species. So right off you have the beginning of stress. And just as different humans can react differently to stress, so too fish. The green citation in my signature block covers this, from a highly respected ichthyologist.

To the question about upgrading to a 70g. I would leave the angelfish where it is, not because this is "good" but because it will remove the "threats." Assuming this is a 4-foot tank, that will address the Pike cichlid. The bichir is also native to very quiet waters, and has poor eyesight. At 20 inches in length, it should have at minimum a 5-foot tank to grow into, but the 4-foot will be a start. Being mildly predatory, small fish may not work with either fish. More on the bichir here:
http://www.seriouslyfish.com/species/polypterus-senegalus-senegalus/
 
The tank I'm looking to buy is 120x40x55cm, so yes its a 4 footer.
Thank you so much for all your advice! it's been very helpful to me.
 
Hi again,
I took your advice and have started to increase my water change schedule.
Yesterday, I did a 50% water change, and today I did another 30% change to try and get my nitrates down as low as possible. I noticed after each change however, that the water appeared unusually cloudy, as if a bacterial bloom were occurring. This disappeared, in both cases, after several hours, but I was just wondering if you knew what might be causing it, and if I should be worried?
 
Hi again,
I took your advice and have started to increase my water change schedule.
Yesterday, I did a 50% water change, and today I did another 30% change to try and get my nitrates down as low as possible. I noticed after each change however, that the water appeared unusually cloudy, as if a bacterial bloom were occurring. This disappeared, in both cases, after several hours, but I was just wondering if you knew what might be causing it, and if I should be worried?

A bacterial bloom probably, or suspended particulate matter in the tap water. A third option is the conditioner. I'll explain.

Taking the tap water first, I have from time to time had cloudy tap water due to excessive rain up in the mountains where our reservoirs are located; not all of this can get filtered out. So that is a possibility and I mention it as such. Harmless.

The condioner...I tried a different conditioner several years back, Big Al's actually, and it did this; after every water change the tank was cloudy. From the data I found online this was confirmed. I tried the BA conditioner because it did nothing other than detoxifying chlorine, which is all I need with my water, but the regular cloudiness which dissipated by next morning was something I wasn't happy with week after week so I changed conditioners. I do not know if any others might do this, so I mention it. Apparently harmless.

Bacterial bloom is the more likely reason. I see this now and then. This is also sometimes related to the tap water, which can be high in organics (microscopic usually). As soon as you put this water in the aquarium, with a dechlorinator, there are heterotrophic bacteria (different from the nitrifying bacteria which are autotrophic) that feed on organics and these bacteria can reproduce very rapidly, in about 15-60 minutes compared to the 12-32 hours for the nitrifying species. Heterotrophic bacteria are faculative anaerobes, meaning they can switch from aerobic to anaerobic and thus do not need oxygen; they are most common in the substrate and filter, and perform essential functions. Here again, this is not a concern, though ammonia can sometimes result, but not usually seriously so. I usually see a mild bacterial bloom after water changes, varying, and after cleaning the canister filters on my larger tanks.

Keep us posted on the nitrate saga, this is important.
 
Just thought I'd let you know that I started using SeaChem Prime, rather than API Stress Coat, and the cloudy water issue seems to have resolved it's self.

After doing 40-50% changes every other day, I have nitrates down to around 10ppm, but I'm struggling to get it down to 0-5ppm. I assume that this is due to the fact that my tank is heavily stocked so I'll continue with my current schedule and increase the water change percentage if needs be.

I have heard that the Pothos Plant is quite effective at removing nitrates if its roots are submerged in the tank. Would you recommend this?
 
Just thought I'd let you know that I started using SeaChem Prime, rather than API Stress Coat, and the cloudy water issue seems to have resolved it's self.

After doing 40-50% changes every other day, I have nitrates down to around 10ppm, but I'm struggling to get it down to 0-5ppm. I assume that this is due to the fact that my tank is heavily stocked so I'll continue with my current schedule and increase the water change percentage if needs be.

I have heard that the Pothos Plant is quite effective at removing nitrates if its roots are submerged in the tank. Would you recommend this?

Aside fro the cloudy water issue, API's StressCoat is not a product I recommend. It contains aloe vera; not only is there no benefit to aloe vera to begin with--it may heal human skin that is somehow irritated, but it does absolutely nothing beneficial to fish in an aquarium--but more significantly is the fact that scientific testing has shown that over time it damages fish gills.

As for Prime, this is a conditioner I would not recommend except in new tanks, or if you have nitrite or nitrate in the source water (tap or well). Prime messes about with water chemistry more than I like when it is not necessary.

Before you ask, a good conditioner is the API Tap Water Conditioner. If all you have to deal with is chlorine and/or chloramine, this is in my view the best product. It is highly concentrated (even more than Prime) so you use less ( which is good for fish as well as saving money), and it does not mess with water chemistry beyond the dechlorinator aspect. It will also detoxify heavy metals, no problem with that.

To the nitrates. Nitrate at 10 ppm is not serious. However, if you do find that they get down to say 0-5 ppm with larger water changes, do them. But depending upon the fish stocking and other factors, it is not always easy to attain zero nitrate. You just want it as low as you can get it. While on this subject, Prime detoxifies nitrate, but this is temporary (for 24-36 hours, after which the bound nitrate is released as toxic nitrate again) so don't factor this product in to the issue. If nitrates are occurring within the aquarium and not in the source water itself, the only way to deal with it is through the biological system.

I don't know anything about the Pothos plant...this is a house plant so presumably the idea would be to allow the stems/roots to be in the aquarium water? May work, but if the plant is toxic, it could harm the fish. Philodendron for example is sometimes suggested for this, but it is toxic and will kill fish.
 
I have seen numerous claims that pothos plants will use nitrates if/when the roots are in the water. I've never been able to get roots to sprout from stem cuttings so I gave up. I think a better alternative would be using floating aquatic plants - anacharis (elodea densa egeria) is one that comes to mind as it is a nitrate sponge (although all plants prefer and use ammonia as their N2 source which indirectly lowers nitrates).
In my 60g low tech heavily planted tank, my nitrates seem to 'hang' at 10-20ppm unless I use a pouch or two of API Nitra-Zorb, but admittedly my tank has too many fish as it's turned into a grow out tank for numerous swordtails.
 
I have seen numerous claims that pothos plants will use nitrates if/when the roots are in the water
 

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