few Question on canister filter

[mwang]

hi, pardon my ignorance...

may i know which tray is with the highest water flow rate? and lowest water flow ?

which tray is reconmended for Biohome and active carbon?

thanks for the advise in advance. : )

[madmac]

mic, the material in the trays within the canister will experience the same flow rate.

Some trays will get the raw water from the tank first ... but the flow thru' rate is the same.

Canister filters are best use for chemical filtration due to their ease of maintenance. If you're using the new modern canisters, where both the water input and output is at the top, then the bottom most tray will contact the raw water from the tank first. The last tray is the topmost one.

So you'll want to have some form of mechanical filtration for the first contact, followed by (IMHO) maybe carbon, then some PO4 removal media.

I don't know what Biohome is. If its nitrifying bacteria, then its not needed, your mechanical filter will provide for that.

[glim18]

I use a 3-tray Eheim canister (I think its the 2228 model) with both in/out pipes from the top.

Bottom tray contains ceramic rings. Middle tray will contain biohome and more ceramic rings. Top tray contains black bio sponge on the bottom, and white fine sponge at the top. It'll be the white sponge that traps the smaller particles before the water is pushed back into the tank.

Note that the pump on the canister filter probably does not push water fast enough if you intend to connect the output of the canister to a chiller or anything else. I have removed the internal impeller of the canister pump and placed an external pump (with a higher flow rate) along the water out line. It's probably a better option to place the pump on the in-pipe between the tank and the canister, but I've not had time to make the change.

Another option will be to keep both the internal canister pump and the external pump running. If your canister pump's flow rate is (for example) 900l/h, and the external pump is 2000l/h, then your flow rate will be between 2000l/h and 2900l/h. Without any fluid dynamics smarts..)...I'm best guessing that the combined flow rate will never be 2900l/h!

Finally, if you do use an external pump and decide not to use the canister pump, I'd remove the impeller as I'm not sure if the canister's impeller will be damaged with water flowing through and the impeller is not moving.

Good luck!

[asg]

i think the tray nearer to the impeller will have the highest flow rate, where the try further to the impeller will have the lowest. the waterflow shall be slow down by the resistant of the wool in the first tray...

[honzo]

the flow through the canister is the same. Logically it is not possible for the different parts of the canister filter to experience different flow rate. If this is true, that would mean that either there will be water flowing to NOWHERE or water is flowing from NOWHERE...

[mwang]

thanks guys for the kind advise

mm thanks for yr help./ cheers!

[madmac]

the flow through the canister is the same. Logically it is not possible for the different parts of the canister filter to experience different flow rate. If this is true, that would mean that either there will be water flowing to NOWHERE or water is flowing from NOWHERE...

honzo, thnx. I wouldn't know how to properly explain that, except to say that its Physics...

mic,

[honzo]

Actually just think in simple terms. For example the canister pump has a flow rate of 1200l/h. So for every hour there is 1200l of water flowing into the canister. If the flowrate through the furthest tray is lower, for example 800l/h, that means that only 800l of water is flowing OUT of the canister every hour. This is not possible because there will be 400l of water unaccounted for.

The misconception probably comes in because although the canister is rated at 1200l/h, it is unlikely that the actual flow will be that due to the restrictions of the media. It is highly likely that the flow rate is only about 1000l/h throughout.

[madmac]

I think, ppl get confuse btw flow rate and pressure.

[honzo]

I think, ppl get confuse btw flow rate and pressure.

Well, I guess they don't teach you everything in a master's degree.

[madmac]

you're funny. ROTFLMAO... thank you.

[asg]

Hi! all see picture.

so long as input = output, there wont be any issue of unaccountable water i.e. flow of tray 1, tray 2, tray 3, tray 4 is equal to input and output.

the flow near tray 1 is fastest, tray 4 is slowest as water has to pass through 4 trays (more resistance) instead of 1 tray.i

f input is 1000l and output is 800l then the caninster will leaks... or the other way round.... caninister runs only one one pump thus input will be same as output... can left leg walks faster than right leg??? it is the average that counts...

hope this help : )

[honzo]

I understand where you are coming from.

The fundamental objective of a filter is to have the water flow through all parts of the filter media. There will be stray flows, but they will be minimal compared to the main flow. I believe most, if not all, of the available brand and models have that design objective in mind.

Your scenario is plausible but not representative of the actual situation.

[asg]

there will be water flowing through all trays but lowest tray will have the slowest flow, as the water has to pass through 4 trays of coral chips/ biohome/ wool/...

[honzo]

mwang,

if you canister has a internal dynamics as illustrated, I suggest you dump it. You are better off putting a power head in your tank.

I believe someone will want to have the last say. Please go ahead. I am not going to post here anymore.

[asg]

??? why so big reaction???

if the caninster is empty or all four trays are empty (filled only with water), i have to say that the flow will be identical.

however, if i place filter wool in the first tray and second tray, then water passing through will:

pass through tray 1 twice (through and fro)

and

pass through tray 2 twice (through and fro)

how will the flow be the same at tray 1 and 4?

another example:

if i place a metal plate with a small hole in tray 1 and a metal plate with two middle holes in tray 2, will the flow in four trays be the same?

(peace) (peace) i am not trying to proof who is right or wrong, i am just trying to show that different flow rate within a caninster can be archive if wanted to.

IMO, biohome will be best place at the last few trays.

[madmac]

andtsg,

canisters don't have such designs, so what you illustrated don't apply. The trays have a circular tube that cascades to join each other when stacked above another. This forms a conduit from the input at the top, to bring the water to the bottom most tray first. The raw water moves from the bottom to the top-most tray. The flow rate thru the canister's main chamber is the same throughout.

I have 3 spare canisters and none are design like how you've illustrated them.

Is ur canister like what you've jus drawn? If it is, then do as honzo suggests... its a very retard design.

[asg]

okie, OIC, Bro.

in that case, can we revert the design? that means place the most resistance material at the lowest tray? as the water going out wont be guided by the conduit anymore...

tray 4 (most bottom) = black wool for large particle

tray 3 = white wool sandwich carbon

tray 2 = biohome

tray 1 (top) = biohome

i am interested in how to maximise caninister as bio filter as i feel that the price is reasonable. if i ever come back to reefing, i will still rely on caninster instead of sump, etc.

i did read a book on linking 4 caninsters in series to serve as a BIG bio/ chemi filters...

thanks bro in advance

[tomowilson]

Hi all,

I think we are all here to help and learn at the same time.....so....yeah keep cool ....water should flow to the bottom via the inlet and raised upwards and pumped out of the canister thru the outlet.....i think thts how canisters nowadays works....

[glim18]

here's an extract from the Eheim pro canister manual...hope this helps this conversation some...

[jackryan]

if you have a sump, would still keep your canisters online?

If yes, why?

If not, why not?