Should I Buy an External Filter?

[DMR123]

Hi,
I'm new to keeping fish and instead of spending hours and hours trying to Google answers and finding nothing, I figured joining a forum where my questions can be answered directly would be a great benefit, so any advice would be greatly appreciated.

I purchased a "Tetra 105L Starter Line Fish Tank" but changed the filter straight away as felt like it was incredibly poor quality and just kept falling apart. So I'm currently using a AquaEl 500 filter. I keep rosie tetra's, cardinal tetra's & black widow tetra's in the tank.

Is there any benefit of an external filter over what I'm currently using. I've read online that its a great benefit, then I've read while searching this forum that it may not be necessary.

Dan

 

[Essjay]

Which filter do you have? AquaEl make a Turbo 500 and an ASAP 500? Both have a turnover of 500 litres per hour which is plenty for a 105 litre tank.
All your fish come from slow moving water and would not appreciate a faster water flow. The Turbo model in particular has plenty media for the bacteria, though once the tank has been running a while there will be bacteria in the substrate as well as on every surface in the tank.

Some reading for you

The Dirty Truth About Filters – MJV Aquatics

mjvaquatics.com

 

[Guyb93]

I like external filters because you tend to have more media space and they aren’t sitting in your tank looking nasty

 

[Essjay]

With 105 litre tank, an external has to chosen carefully making note of the filter's turnover. An external made for a large tank could turn it into a whirlpool, not recommended for fish from slow moving water. There are suitable externals out there, you just have to read all the technical details carefully.

 

[Guyb93]

With 105 litre tank, an external has to chosen carefully making note of the filter's turnover. An external made for a large tank could turn it into a whirlpool, not recommended for fish from slow moving water. There are suitable externals out there, you just have to read all the technical details carefully.

Don’t most external filters have flow control though to prevent that ? I have never used the flow control on mine as I’m always looking for the maximum output but does actually using it hve a negative am effect on the filter istelf ? Would you have to match the in and out flow ? Or would just adjusting the outflow do it all

 

[Essjay]

Some do, some don't. It depends on the brand. Most good makes do.

 

[seangee]

I have an Aquael 500 turbo and an Aquael PAT mini. Both are great filters and have a small footprint so are quite inconspicuous.
External filters that are adjustable for flow only work within a range and most will turn a 105l tank into a whirlpool even on minimum. I would suggest stick with what you have and only look to change after 6 months if it does not meet your need.

 

[Guyb93]

I have an Aquael 500 turbo and an Aquael PAT mini. Both are great filters and have a small footprint so are quite inconspicuous.
External filters that are adjustable for flow only work within a range and most will turn a 105l tank into a whirlpool even on minimum. I would suggest stick with what you have and only look to change after 6 months if it does not meet your need.

I think a fluval 206 would be a great filter for that tank , max out put would be 7-8x the tank volume a hour
And it has flow control to reduce
I’m a big fan of external filters to be honest

 

[eatyourpeas]

I have canisters in my 6 gal. and 12 gal. tanks and they work beautifully. There are ways to tame the output flow with either a spray bar or sponges.

 

[seangee]

I think a fluval 206 would be a great filter for that tank , max out put would be 7-8x the tank volume a hour
And it has flow control to reduce
I’m a big fan of external filters to be honest

Read the link @Essjay posted. I am a massive fan of enough filtration and no more.

 

[Guyb93]

Read the link @Essjay posted. I am a massive fan of enough filtration and no more.

Is there enough filtration? If flow wasn’t an issue surely you can’t have enough filtration

 

[Essjay]

That is a fishkeeping myth. As long as the filter traps all the bits, and there are enough bacteria/plants in the tank to remove the ammonia made by the fish, there is no point in going bigger.
Bigger filters can trap more bits but they don't improve the water quality compared to a smaller filter. It's the bacteria/plants that improve water quality; plants don't live in the filter and bacteria grow everywhere.

Contact Support

 

[seangee]

Is there enough filtration? If flow wasn’t an issue surely you can’t have enough filtration

If the tank has no ammonia or nitrite the (biological) filtration is sufficient. In my tanks I still have no ammonia or nitrite if I replace the filter with a powerhead that does nothing but move the water (yes I have tried). The downside of this as @Essjay points out is all the "bits" stay in the tank so it looks mucky. Fish are not overly worried about this but owners are. So I have small filters that give me enough flow for the fish I keep and use sponge to trap the bits. I rinse these sponges weekly.

Now if I were to replace these small filters with massive canisters I would be unlikely to clean these weekly. Once the debris arrives in the filter it stays there. As it decomposes it produces ammonia. Of course the bacteria in the filter deal with this - but the end product of this is nitrate, so in effect you have a nitrate factory sitting outside your tank. Besides nitrate going up this means the plants are being starved of ammonia and you may have to use supplemental fertilisers. It is true that plants can use nitrate but to do this they first have to convert the nitrate back to ammonia, which requires energy.

I changed the water in the 3 small tanks yesterday so checking for nitrates would be pointless. But this morning I changed the water in the 180l tank and before the water change my readings for ammonia, nitrites and nitrates were all 0. This tells me the small HOB with a single sponge inside it and the sponge filter down the other end are adequate. The 0 nitrate tells me the plants are using 100% of the ammonia that is produced and my filter media most likely has very little active bacteria. The water is clean, fish are healthy and plants are healthy. I do not fear a filter failure because if it dies the plants will continue to deal with the ammonia. I do not fear having to leave home for 3 weeks and not changing water because the nitrates will never build up (I still do a 75% w/c every week when I am home). The HOB is rated for a 200l tank and flow set at minimum.

Here is the most recent pic of the tank. I have not cleaned the substrate since Sept 2019 (when it was changed) and wipe the front glass with a sponge every 2-3 weeks. I don't touch the other sides because they belong to the fish.

Please note - I am not saying throw out your filters or even aim for reduced filtration. But there is no point in over filtration and some downsides, and in a well balance environment you don't need nearly as much as filter manufacturers or retailers will try to sell you.

 

[Guyb93]

If the tank has no ammonia or nitrite the (biological) filtration is sufficient. In my tanks I still have no ammonia or nitrite if I replace the filter with a powerhead that does nothing but move the water (yes I have tried). The downside of this as @Essjay points out is all the "bits" stay in the tank so it looks mucky. Fish are not overly worried about this but owners are. So I have small filters that give me enough flow for the fish I keep and use sponge to trap the bits. I rinse these sponges weekly.

Now if I were to replace these small filters with massive canisters I would be unlikely to clean these weekly. Once the debris arrives in the filter it stays there. As it decomposes it produces ammonia. Of course the bacteria in the filter deal with this - but the end product of this is nitrate, so in effect you have a nitrate factory sitting outside your tank. Besides nitrate going up this means the plants are being starved of ammonia and you may have to use supplemental fertilisers. It is true that plants can use nitrate but to do this they first have to convert the nitrate back to ammonia, which requires energy.

I changed the water in the 3 small tanks yesterday so checking for nitrates would be pointless. But this morning I changed the water in the 180l tank and before the water change my readings for ammonia, nitrites and nitrates were all 0. This tells me the small HOB with a single sponge inside it and the sponge filter down the other end are adequate. The 0 nitrate tells me the plants are using 100% of the ammonia that is produced and my filter media most likely has very little active bacteria. The water is clean, fish are healthy and plants are healthy. I do not fear a filter failure because if it dies the plants will continue to deal with the ammonia. I do not fear having to leave home for 3 weeks and not changing water because the nitrates will never build up (I still do a 75% w/c every week when I am home). The HOB is rated for a 200l tank and flow set at minimum.

Here is the most recent pic of the tank. I have not cleaned the substrate since Sept 2019 (when it was changed) and wipe the front glass with a sponge every 2-3 weeks. I don't touch the other sides because they belong to the fish.

Please note - I am not saying throw out your filters or even aim for reduced filtration. But there is no point in over filtration and some downsides, and in a well balance environment you don't need nearly as much as filter manufacturers or retailers will try to sell you.

Good info , I aim to turn my tabk over 6x a hour with my external , and do have a small internal hiden in there aswel I have greedy messy fish and I’m a sucker that gives in to them and feeds them lol probably why I’m after max filtration plus my pleco is a messy bugger

 

[Essjay]

Ah yes, you have a big tank with messy cichlids in, @Guyb93
Those of us who don't have fish like this don't need over filtration, but it may help with your fish. Don't forget that with messy fish you will need to clean the filter regularly.


My tanks are similar to seangee's - zero ammonia, nitrite and nitrate. My test kit measures my tap nitrate as between zero and 5 ppm, and my water company confirms it as 4 ppm. The surfaces of both my tanks are covered with Amazon frogbit, so they will remove all the ammonia made by the fish, and the bit of nitrate in my tap water. As you can see in my signature, I don't have messy fish.
I once forgot to plug the internal filters back in after a water change and only discovered the following week. There was zero ammonia and zero nitrite in the water.