Joining 2 Filters In Series ?

[MadMan-JaMeS]

I've got two small filters running on my tank which are Eheim 2215's.

i wondered if i could put the outlet from one into the inlet of the other to increase the flow and make them more powerful as they don't create much water movement on thier own

Any thoughts ?

 

[The-Wolf]

yes you can run both in series but it won't increase the flow.
if you can the outlet pipe of each to a smaller diameter or change the
spray bar to a smaller and shorter one, this will increase the flow somewhat.

 

[rabbut]

Rigging in paralell works, and increases flow I have tried it and it works fine. I diden't go down the series route that I origionally wanted to, as I realised with thought that it may shorten the life of the filters, as the motor heads in series would be under increased load if only using one, and the second filter would become a pressuried unit if both motors were used (something they aren't intended to be) and this could lead to leaking. If you want to wire two together, do it in parallel

 

[MadMan-JaMeS]

do it in parallel

Can you explain how i would do this ?

 

[geo7x]

Indeed working them in a series would not increase flow, as the second pump would not have any more turnover power than the first so the flow would just stay constant.

What I think rabbut means is if you have each filter running seperately but join them both up to the same spraybar through one of those T (or Y, dunno what they're called) attatchments then you would have double the output. I suppose you could in theory run them both off the same inlet as well if you wanted to. That way the filters are in no way connected to each other but are rather connected to the same outlet within the tank.

This is my understanding of 'running in parallel' anyway, looks like it would work.

 

[geo7x]

Dodgy paint drawing:

View attachment parallel.bmp

Dark green hose: inlet Light green: outlet.

Not too sure if combining the two inlets would work but if not you could just have two in the tank.

 

[SJ2K]

Looks like a damn good idea, would also reduce clutter in the tank

Option 3) Sell both filters and buy 1 larger, more powerfull model

 

[andywg]

The problem you have is pipe diameter. Wherever you have both pumps' return or feed water running through the same pipe you will need to have a pipe with a cross section roughly twice that of the original pipework, otherwise you will be reducing the total flow.

I think some people are confusing the amount of water flowing with water speed. If you restrict the flow (or put two outputs through a pipe designed for one) then you create back pressure which reduces the total flow. However, through the small gap at the end it will feel to you like it is a much more powerful flow as it is a narrow stream of water moving quickly. Reduce the pressure and you actually have more water being moved around, just across a wider plane and so it feels less strong to your skin.

If you want to get a better idea of what I mean, try and find a friendly Salt water keeper or lfs with propellor style powerheads (the Koralia Hydor or Tunze Streams). Put your hand in front of a standard powerhead and the force from the output feels strong as it is a needle jet moving into your hand, put it in front of a Tunze Stream and it doesn't feel very strong as it is moving far more water across a wider plane. Below is a picture from the Tunze website indicating how the propellor style powerheads shift more water for less energy:

The top picture is a standard powerhead with a needle like flow, the middle an old Turbelle pump and the bottom a Stream Turbelle pump. the top one feels stronger, but the bottom one is moving the most water.

 

[geo7x]

So you would need to find a compromise between concentrated pressure and total flow. If you are after more pressure and a faster flow then have a narrower hose, but if you want maximum total flow then have a wider hose.

It depends if you want maximum pressure or turnover.

 

[rabbut]

The connector you need;

The inlet and outlet are of each filter are connected to the same set of pipes in the tank, which are the same diameter hosing in my case, but they should be double the thickness, but double thickness pipes wouldn't fit the gap for them in the stress bars on my tank The inlet should come out of the tank, and go into a T junction as shown above. Ideally, you would then pass each outlet from the T piece to a reducer, to go back down to the filter pipe bore size (assuming the inlet set are larger than those of the filters) before then going on the the filters On the outlet side, you would have the same pipework, only in reverse, pipe through a reducer, then a T piece and then the outlet pipe-set

HTH
Rabbut