external filters

Byron

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In regards to the filter, I've always read that you can't "over filter" water, and if the flow is too powerful in terms of water movement you can point it at a tank wall or decor etc to slow it down
This is one of the several myths still being expounded in the hobby. There is no benefit to "over filtration" but there is usually a detriment, to both fish and filtration itself. I touched on the fish aspect previously. As for filtration, a filter can only do what is required by the system; if the filter is adequate for the biological system, it will do the best job of filtering the water...in so far as that goes. Adding more filters, or larger filters, or faster-flow filters, will not improve filtration; it could actually lessen it. Nitrification, which is what we usually expect the filter to deal with, cannot occur if the water flow is too fast through the media. And it will occur at the level required for the biological system provided the filter is adequate, but no more. There is no "more" filtration possible. And besides that, this nitrification will take place in the substrate anyway. And if you have live plants, you lessen the need for the filter even further.
 
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JLawson90

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I don't have live plants and don't plan to add them.. and I'm not talking about some mega insane external filter as well as in my submerged one, it would be to replace the submerged one .. my tank is 125L / 27.5 Imperial gallons / 33 US gallons .. so while not an overly big one, it's not a small one either so I don't think an external would be overkill
 

Byron

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I was responding to your comment on the popular advice you can't over filter, attempting to show that in fact you can and it is detrimental both to the fish (depending upon species) and certainly to the filtration effectiveness.

As for the external on the 125 liter tank...it depends entirely on the intended fish. I have this size of tank in my fish room, and it had a dual sponge filter for over ten years that was more than sufficient. It now has an internal filter which is nothing more than a small motor and sponge (no chemical media). In post #1 you mention budget being an issue, and that is understandable for most of us, so why waste the money on something that is not going to benefit?
 

AbbeysDad

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I pretty much agree with Byron...filtration seems to be incredibly misunderstood in the hobby. I/we see it echoed all the time: "there's no such thing as too much filtration" and "you need 4x to 10x GPH relative to tank size for filter flow". And the confusion often extends to well meaning experienced hobbyists, Youtubers, and writers.
Stop the madness. :)
Good filtration is about how well we filter water, not how much or how fast it's pushed through media.
Pushing more water, faster, through one or more filters does very little for mechanical filtration and even less for biological and chemical filtration as for these, we need sufficient dwell time to be effective.
Imagine if we filtered every drop really well, why would we need to re-filter the same water many times an hour? And lets be clear - filters don't clean water, they merely make it look clearer. Trapped detritus in the filter decomposes and pollutes the water. Many filters are nitrate factories. A better filter would be easy to service mechanical media AND serviced frequently to get the crud out of the system!

As for biological, there is far more surface area in the substrate of the typical tank than would be found in any filter. And filter bio-media and chemical additives like carbon and resins are far more effective with slower flow rates so offensive elements don't blow right past. Many hobbyists add great volumes of so called bio-media thinking it will offer more or better biological filtration. But the beneficial bacteria colony size is always relative to the available food (ammonia/nitrite) and oxygen - regardless of the amount of suitable surface area.

As Byron points out, fast growing plants convert nutrients (aka pollution) into plant tissue that's eventually removed by trimming...and this reduces the need for extensive bio-filtration.

Finally, many if not most of the fish in our hobby were tank or pond raised and didn't come from raging rivers. To assume fish need or prefer fast currents is just wrong and can be very stressful for many fish.

Much better than any filter, the best water quality is provided by routine periodic water changes of sufficient volume.
 
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JLawson90

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I understand what you're saying, but surely there are more pro's than con's to an external filter.. providing it is not ridiculously overpowered for the tank .. the fluval 206 for example is 1150LPH, which works out at approx 303 US gallons, which is 'only' 2.4xGPH

I dont want a lot of fast flowing water, I've not said that, and again I wont be adding any live plants to this .. but regardless of whether it is internal or external I will be replacing the filter, as the one that came with this tank is crazily loud and annoying

external filters also remove the big ugly black box from inside the aquarium, better on the eye
 

essjay

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A filter that has a turnover of 1150 litres per hour on a 125 litre tank will turn over just under 10 times the tank volume per hour. This is far too much for anything but fish that come from fast flowing rivers. Fish that come from slow moving rivers or lakes would be very stressed by that turnover.
 

Byron

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I understand what you're saying, but surely there are more pro's than con's to an external filter.. providing it is not ridiculously overpowered for the tank .. the fluval 206 for example is 1150LPH, which works out at approx 303 US gallons, which is 'only' 2.4xGPH

I dont want a lot of fast flowing water, I've not said that, and again I wont be adding any live plants to this .. but regardless of whether it is internal or external I will be replacing the filter, as the one that came with this tank is crazily loud and annoying

external filters also remove the big ugly black box from inside the aquarium, better on the eye
The important aspect is the fish, not appearance, when you come down to it. Over my 30 years I have had canister filters, HOB filters, internal filters, and sponge filters connected to an air pump. And one tank ran for a year with no filter.

This link is the small internal filter I now have on my 33g tank.
https://www.jlaquatics.com/dry-good...eon-quietflow-internal-power-filter-at15.html
This filter is rated for up to 15 gallon tanks. It produces just the right amount of surface disturbance. The tank is pictured below. I don't even know this filter is in it, without checking the water surface at the rear right side for rippling. This tank holds dwarf loaches, rasboras.
 

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seangee

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This is the seachem tidal 35 - around £45 in the UK. As you can see not much of it is visible as most of it is over the back outside the tank. It is also completely silent - this one is in my study where I often spend the full day working. Ideally you would fit it at the narrow end but I was lazy because my tank lid had the right size hole where it is. I only have a couple of pieces of sponge inside this one and the supplied media is still in the box.
20191018_192702.jpg

In case you're wondering about the powerhead these are some of those super active fish that like fast flowing water that @essjay refers to. If I had sedate fish the tank would only have a sponge filter that @Byron mentions - they only cost a tenner on Amazon but be aware that cheap air pumps are not silent. A decent air pump + sponge filter will probably still cost you less than the HOB (hang on back) filter.

Oh and plants are highly recommended for a healthy system. Those floaters (frogbit) are almost zero maintenance. I trim the roots every few weeks and when they get too thick on the surface I throw a few handfuls out. I don't do anything else for them.
 
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JLawson90

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If that one is too powerful then that's fair enough.. I have also seen an 'all pond solutions' one that I believe was 400LPH too powerful still or about right?

I do actually have a hagen elite stingray 10 in a box somewhere which is around 200LPH?
 

essjay

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Stingrays are not my favourite filters. The media is mainly carbon & zeolite with a small piece of sponge, and they are notorious for fish getting stuck between the filter casing and the glass. The stingray 10 is rated for tanks up to 50 litres; I wouldn't use it as the only filter in a 125 litre tank.

A lot of people like APS filters, the only criticism being that the plastic is quite flimsy. As long as you are aware of that and be gentle when handling it, they are good filters.
 
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JLawson90

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I only suggested the stingray because of the previous comments, I did think it wouldnt be enough hence me putting up with the annoying volume of the one in there lol .. I'll probably go for the APS one when it comes to replacing it
 

seangee

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Lift the spraybar higher. You want the water to break the surface (at least cause ripples). If the flow is too strong aim it at the back wall and upwards.
 
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JLawson90

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I'm not sure if you can see both pics, the full tank one for me is showing as an X? but anyway, unfortunately I can't alter the spray bar as the weight of it pulls it down.. you cant tell from the pics properly but the holes are pointed diagonally upwards to the surface, i'll try upload a short video to show the surface movement, I think it's enough but let me know if not ..
 
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