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Real Flow Filter Rate list

R

Radik

Member
Joined
26 Oct 2010
Messages
588
Location
London
Hi Gang

I was wondering if you folks could write here your real flow rates on your filters and maybe we could create some guide based on experience. Filters are expensive and purpose is simple to avoid junk filters and to help others decide what is worth and what is not. As I am now struggling after disappointment with TetraTec Ex600 and going to buy something more powerful.

I am planning to get new tank between 65-80 liters heavily planted and I was considering to get one of these:
JBL e900 or Eheim 2071 or Hydor Prime 30 or Aquael Unimax 250. I would like to hear their real flow rates.

Just measure how fast will your 1 liter cup will be filled up then 3600/time to fill one liter.

Here what I measured or gathered:
Aquael MiniKani - Rated 300LPH - Real 225LPH
TetraTec Ex700 - Rated 700LPH - Real 360LPH
TetraTec Ex1200 - Rated 1200 - Real 700LPH - Thanks to Tom
 
I dont know if that would be an easy one for people to gather the same info. We would all have to have the same media load, diameter and length of hose. The height above the filter and whatever was on the end of the hose would all have to be the same :? I believe the general rule of thumb is about 60% of stated, but there are so many variables.
 
They don't have to gather the same info, the point will be that you get a range of real life data and then average it all so people have a real-life expectation of performance as long as lots of people all offered their data and the results could then be averaged.

I think this would be a good thing for us to do as a society but think it might be better to use a larger container than a 1l one. Any small error with that will be compounded by the small sample size. A 10l bucket would be better by a factor of 10.
 
That's correct Ed, averaged info would be more than enough. For some bigger filters people can use larger containers for those around 700-900 rated it takes around 10 seconds to fill it.. I did measures 5 times and it was always same also filter and tank level had small difference in my case.
 
Hi,
We already have an average. Filters generally produce 50% of their rated flow on average. Some people will measure around 40% and others will measure up to about 60%. The 10X rule is based on this average.

The values you get are depend on the following:
1. The amount of media.
2. The type of media.
3. The length of tubing.
4. The distance from the water's surface to the filter inlet.
5. The length of time the filter has been in service.
6. The cleaning and maintenance regimen practised by the hobbyist.
7. The number of restrictions caused by add-ons such as reactors and external heaters, as well as the outlet apparatus such as lily pipes or spraybars.

These are all cumulative effects and it should come as no surprise if your filter only delivers half of it's rated flow. Filter manufactures do not rate their filters based on the worst case conditions. The filters flowrate is typically measured while it is unloaded. Some manufacturers have more optimistic ratings than others. Eheim are among the worst offenders.

Cheers,
 
Yep, that's right. The original calculations were that the plants needed between 3X-5X the tank volume per hour of actual flow. Knowing that the filters typically only delivered half their quoted numbers because of the manufacturers cheeky rating practices, you would simply double this range so that the values would be 6X-10X the rating. 10 is a nice easy number and it's better to be on the high side to account for blockages caused by plant growth, hardscape and dirt accumulation.

A 10X flow rating, with good distribution (let's not forget that important factor) will generally produce a gentle movement of all the leaves, which improves the nutrient uptake and CO2 uptake efficiency of the leaves. The movement also has a tendency to reduce biofilm or debris buildup on the leaf, further improving their uptake efficiency.

People with un-planted tanks (or with low tech non-CO2 enriched tanks) don't really care about all this. They are only interested in the ammonia pull-down capability, so these actual-vs-quoted flow rate values are not an issue for them.

Cheers,
 
Hi guys

So is there a case of having too much flow? E.g 15X flow rating. What would be considered as too much?

Or is it the fact of the more flow the better?
 
I think that would depend on how the flow is distributed, you don't want all your plants lying flat under the force of a jetted flow.
On the other hand if you used 4 spray bars you could spead the flow around but, the point is about how much flow is required to spread the C02 around the tank & into every nook & cranny.
 
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