# Filters



## Wolfie (7 Sep 2020)

Does an external filter have to be underneath the tank or is it able to function just the same next to the tank?


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## Zeus. (7 Sep 2020)

Wolfie said:


> Does an external filter have to be underneath the tank or is it able to function just the same next to the tank?



Makes little to no difference for most setups, having it lower than tank will make it easier/quicker to prime as a siphon works better with a bigger head of water, once the filter is primed the shorter to pipework/hose the less the resistance to flow.

So minor pros and cons in most cases


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## Wolfie (7 Sep 2020)

Zeus. said:


> Makes little to no difference for most setups, having it lower than tank will make it easier/quicker to prime as a siphon works better with a bigger head of water, once the filter is primed the shorter to pipework/hose the less the resistance to flow.
> 
> So minor pros and cons in most cases


That’s good to no, the filter ie Eheim 2213


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## ian_m (8 Sep 2020)

Most external filters will have requirements like this.


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## dw1305 (8 Sep 2020)

Hi all, 





ian_m said:


> Most external filters will have requirements like this.


Exactly like @ian_m says. I have my filters <"sitting next to the tanks">. Eheim Classics don't have a <"large head height requirement">, but you do need to keep the hoses clean etc. or you will have problems with noise and filter damage.

cheers Darrel


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## Zeus. (8 Sep 2020)

ian_m said:


> Most external filters will have requirements like this.
> View attachment 153862



Although the head of pressure in some ways is irrelevant IMO, as the same head of pressure will be on the inlet as the outlet so the pump should still work even with as say 50 meters head of water (ignoring the resistance of the hose/piping). But the head of pressure will relate to the pressure of water in the canister/filter can withstand without leaking/blowing a seal etc 

I did give it some thought that if you had a CO2 reactor with a large head of pressure the CO2 uptake of the water could be pretty awesome, if I had a cellar I would give it a go but would need a pretty robust reactor to handle the extra pressure. maybe in next house  - plus a lake and a bore hole for water so can do RO water, geothermal heating would be nice too..........

 I've accidently blow the lids off my APS EF2 reactors turning the water on to fast when filling my tank a couple of times 🤣 it was all hands on deck for a few minutes


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