Eheim 2213 + Hydor Seltz L30 inflow or outflow??

[herezor]

Hi all

I have a question before I buy this pump (Hydor Seltz L30). My tank is a 60x30x45 cm on its 8th week DSM. I will flood it probably next week, I´ll attach an Eheim 2213 filter that I currently have attached to a box to keep my fish. It is just 1/3 full with foam and still the flow is rubbish and far from the 10x flow rule. What I plan to do, instead of upgrading the canister is to buy this Hydor pump. It is rated at 1200 lph which should be more than enough (15x).

I did a search in the forum to see if my idea had come up before. I read all threads related and what I plan to do is perfectly possible. Just unplug the 2213, take the impeller out and run the inline pump. So far, so good. But here comes my question. Where do I place the pump?. Inflow or outflow....?

I´ve read pros and cons of both placements. Some say it is best to place it on the outflow so the water that passes through the pump is clean so less maintenance is needed. But pumps are designed to push water not to pull it from the canister, so they may cavitate due to flow restriction.

Those who say it is best placed on the inflow support their suggestion based on the same fact. It is better to push water through the canister plus the pump will be easily primed this way, but some others suggest that this will increase pressure on the canister joints and may trigger water leaks.

I know there are other ways to improve flow like in-tank powerheads, but I want to keep the tank as free from equipment as possible. So, the question is... where do I place the pump, inflow or outflow?

Thanks to everyone

Cheers

Pedro

 

[Steve b]

Hi pedro

In my experiance as a heating engineer and koi pond keeper,
Pumps are usually fitted to the return or clean water side of the filter.
Reason is as you say most pumps are designed to push water.
The other thing to rember is In front of the pump creates positive pressure and behind negative pressure if you fitted your pump on the return to the tank after the filter the filter would be under negative pressure.
Which means if the filter developed a leak while the pump was running it would draw in air .
If you fitted your pump on the dirty water feed from your tank to the filter,
And it developed the same leak it would spray water out because the filter and everything after the pump is under positive pressure .
Another thing to bear in mind is pump head loss, and if your pump can pump dirty water.

Hope this helps


Steve