Are Advertised Flow Rates Bogus?

[MattyM]

I'm doing some research into canister filters, in particular to the Oase Biomaster line. Let's say I'm putting together a 100 gallon planted community tank (70% planted). According to the Oase site, the Biomaster 600 would work. Their site says that this filter is suitable for tanks up to 160 gallons, and has a max flow rate of 350 GPH, that sounds pretty good! I'll inject some CO2, but nothing crazy - just a boost, maybe dropping half a ph point. 

BUT - from what I've found, flow rates could be measured with an empty canister - as in, no media. If so, and I stuff that thing with media, I assume I'd get much less flow than what the specs for this filter say. So... maybe I'd need to size up? 

Is that true? 

[Galabar]

In terms of flow, these folks found that there wasn't much different in biological filtration capacity for a 2X increased flow (canister filters): https://aquariumscience.org/index.php/8-3-1-canisters-in-depth/

If this is true, it may be that water flowing faster over biological media only increases filter capacity by a small amount (to some maximum).

Instead, it might be useful to consider the area of the biological media that you'll have (and attempting to optimize that area with the "best" media).

In terms of flow in the tank, it's easy to create flow with cheap power heads on either side of the tank...

Edited July 3, 2023 by Galabar

[nabokovfan87]

On 7/3/2023 at 2:49 PM, MattyM said:

BUT - from what I've found, flow rates could be measured with an empty canister - as in, no media. If so, and I stuff that thing with media, I assume I'd get much less flow than what the specs for this filter say. So... maybe I'd need to size up? 

This is why the common advice is to get the "next size up" when you get your filtration.  The goal is to have adjustability on the flow side or at least a method where you can temper the output flow if you need to.  Eheim is supposed to have info on their website that pondguru is always referencing for stocking recommendations on the filter.  When it comes to certification of products it's kind of a joke that they don't test with a complete unit and the industry really should require better for itself.

Maybe there is a pump / size equivalent you can use off a reference with their data to sanity check the setup.

 

[Galabar]

I wonder if they also test without hoses or restrictions of any kind on the outlet?

[Mmiller2001]

I would run 2 600’s on a 100 gallon tank if the idea is to run CO2.

[AndEEss]

I’d run two 850s.

In addition to processing ammonia/nitrite, a filter also oxygenates your water, which helps break down organics. It also helps supply oxygen, obviously.

Most filters put out about 50-60% of what the *pump* can do, with a 5’ head, filter material, etc. Check out the Fluval FX6 page for an example of them listing both.

Edited July 4, 2023 by AndEEss

[MattyM]

On 7/3/2023 at 11:00 PM, Mmiller2001 said:

I would run 2 600’s on a 100 gallon tank if the idea is to run CO2.

I was pondering that. How would you place the inlet and spray bars? I saw a Green Aqua vid where they placed an intake and spray bar on each side, pointing at each other. 

[Mmiller2001]

On 7/5/2023 at 7:38 AM, MattyM said:

I was pondering that. How would you place the inlet and spray bars? I saw a Green Aqua vid where they placed an intake and spray bar on each side, pointing at each other. 

I’d go each side intake and spray bar front to back. 
 

As mentioned, 2 850’s would be even better.

[MattyM]

On 7/5/2023 at 8:52 AM, Mmiller2001 said:

As mentioned, 2 850’s would be even better.

Those 850s are like skyscrapers! No way those are fitting under the tank I’m planning but I get the idea, tx!

[Mmiller2001]

Just remember more flow/turnover is better. I run 3 pumps rated at 535gph each on my 120.