How to choose a suitable filter

**Jojowhisky** · 20th Dec 2018, 13:50

Hello everyone!
Have been looking around trying to find articles on finding the best filter for a tank.
(Cant find what i was looking for)
How do you guys know if the filter is indeed going to be sufficient for the tank intended?
Is there a calculation that can be done based on the info on the filter box? If so, please enlighten me.
An example is i will see on the box of the filter(200litres/hr), what does this translate into a tank whose capacity is maybe 10litres? (Figuritive example).
Most of the time i noticed, companies will just put the tank capacities on the box and they just direct you to the model suitable for it. Would just love to learn from you guys how do you pick the right filter base on what the box tells you(×××litres/hr).
Cheers.

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**torque6** · 21st Dec 2018, 23:44

It is recommended on average to "turn" over your aquarium volume 4-6 times per hour. So if you have a 100 litres tank, your filter flow rate should at least be 400L/H to 600L/H. However, it also depends on the type of live stock you are keeping. Some fish prefer low flow. Shrimps with only sponge filter have an even lower flow.

Canister filters like eheim show the actual flow capacity without resistance; meaning no course sponge, no mechanical media. So if you add those with an over height of 1.2 meters, then the flow rate will be reduced by half (based on test done by Planted Forum; many years back). However results may vary.

This by the way is not applicable to salt water aquariums.

**Jojowhisky** · 22nd Dec 2018, 00:11

Thank you for the detailed analogy.
Will surely use your guideline when hunting for a filter whenever im out there looking for one. At least now i know the basic guideline, makes lookin for a suitable sized filter easier and clearer.
Boxes can only give you specs but if i dont know what to look out for than very frustrating.
Thanks for clearing my question.
Cheers and happy holidays.

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**torque6** · 22nd Dec 2018, 00:31

Originally Posted by Jojowhisky

Thank you for the detailed analogy.
Will surely use your guideline when hunting for a filter whenever im out there looking for one. At least now i know the basic guideline, makes lookin for a suitable sized filter easier and clearer.
Boxes can only give you specs but if i dont know what to look out for than very frustrating.
Thanks for clearing my question.
Cheers and happy holidays.

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If you are hunting for a filter, then you also need to know the following besides flow rate :-
1) Generation of heat. A filter pump which runs hot and dump warmer water into your tank is not so good.
2) How quiet the filter runs?
3) Look for options, Over head filter vs Hang On vs Canister etc. Hang On being easy to operate but may have splashing sound, while canister filters on occasions do trap air and thus could be noisy etc. Hang on easy to clean, canister have pipes, tubing to clean etc.
4) Read reviews on reliability (leaking etc etc).

Happy hunting.

**Jojowhisky** · 22nd Dec 2018, 00:54

Will do.
Canisters are a science again. Kind of like guns for the big boys (because so many tubes and pipes!!!) But i know they do an excellant job with filtration if done and maintained right! Will probably dive into that when i get better in knowledge and experience(dont want to get too ambitious for now)
No point basics not there than get big huns but dont know baseline and dont know how to use these expnsive equipment.
Just want to dive deep into basics and experience like how to pick a suitable filter for the tank(which you explained) and im getting there with stability in parameters day by day.
So im working on those but great input you gave, im gonna be more informed now when i look at the filter specs on the boxes. Temp output from the filter like you mentioned is also key, thank you for pointing that out to remembrance.
Excellant advice thank you.

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**afnsa** · 8th Jan 2019, 10:30

Hi Jo! There are many different school of thoughts as to choosing the suitable filter.

Personally after researching (I'm very intrigued by filtration

), one of the most important thing is surface area. The balance between surface area and flow rate is one that eventually comes down to experience to find out what is needed for your tank. I'm focusing on biological filtration here because sort of the determining factor for "need".

Also, just as important as the size of the tank, or if not more, is the stocking. What do you keep inside, how much waste do they produce, how clean do they need the water to be and how much flow can they handle.

High flow rate does not necessarily equate to more filtering capacity. If water flows through little media at such a fast rate, the bacteria cannot break down ammonia and nitrites in "1 flow" and hence it will just have to turn over more times. Also high flow rate might be undesirable for your inhabitants as well. What do you keep?

Sorry if everything is so vague and "depends" kind of answer. I guess the most solid advice I can give is if you keep fish and the tank is under or appropriately stocked, roughly follow manufacturers guidelines and go with trusted brands. If you keep sensitive species or species that produce massive waste or you over stock you tank, aim for 2x filtration capacity. ie. 100 gallon rated filter for 50 gallon tank.

The only sure way to tell is to test for ammonia and nitrite. Unfortunately that means you would have already bought a filter and its like lesson learnt and experience gained. I hope this helps!!

**afnsa** · 8th Jan 2019, 10:34

Oh and most filters do rate their filter capacity for the sized tank on top of providing flow rate. So look out for that. Once you observe enough filters you will get the rough idea of like xx gallon tank usually requires xxx flow rate. And then from there you adjust based on your tank stocking.

**Jojowhisky** · 9th Jan 2019, 03:44

Originally Posted by afnsa

Hi Jo! There are many different school of thoughts as to choosing the suitable filter.

Personally after researching (I'm very intrigued by filtration

), one of the most important thing is surface area. The balance between surface area and flow rate is one that eventually comes down to experience to find out what is needed for your tank. I'm focusing on biological filtration here because sort of the determining factor for "need".

Also, just as important as the size of the tank, or if not more, is the stocking. What do you keep inside, how much waste do they produce, how clean do they need the water to be and how much flow can they handle.

High flow rate does not necessarily equate to more filtering capacity. If water flows through little media at such a fast rate, the bacteria cannot break down ammonia and nitrites in "1 flow" and hence it will just have to turn over more times. Also high flow rate might be undesirable for your inhabitants as well. What do you keep?

Sorry if everything is so vague and "depends" kind of answer. I guess the most solid advice I can give is if you keep fish and the tank is under or appropriately stocked, roughly follow manufacturers guidelines and go with trusted brands. If you keep sensitive species or species that produce massive waste or you over stock you tank, aim for 2x filtration capacity. ie. 100 gallon rated filter for 50 gallon tank.

The only sure way to tell is to test for ammonia and nitrite. Unfortunately that means you would have already bought a filter and its like lesson learnt and experience gained. I hope this helps!!

Nah, that was a good write up by you!
At least it directed me to answer some questions myself after reading your write up. (You know, questions to ask myself whilst looking for filters)
That was why i asked the question before looking.
One can get so distracted in an aquarium store. *guilty*
Its like taking a walk in daiso, you end up getting a load of stuff that you dont need. (Me)
Thanks for the write up as mentioned. It was good nevertheless. #schooled

I keep shrimps and may look to upgrade the tanks to larger capacity as we are expanding(pregnant mummies), also itchy fingers what to find excuse to scape more tanks haha.

Cheers.
Jo

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**afnsa** · 9th Jan 2019, 21:55

I'm guilty of getting distracted in aquarium stores too

And yes, any excuse to upgrade tank is valid!!

**simonyeeklang** · 16th Jun 2020, 16:29

a Filter is a Filter but the issue is when you have a filter you suppose the filter is on the ground.
and the tank is 1/2 feet higher.
Water pressure and air pressure.
Once you have bleed all the air out the filter is quiet.
This also effects the out put of the water.
So no all the filters are created equally.
if you dont clean out the filter media properly no matter how expensive it still will jam