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Actual flow is 25% of rated flow (Eheim Pro 3e 2076)

tyrophagus

tyrophagus

Member
Joined
1 Apr 2010
Messages
244
Location
Swindon
I'm suprised its taken me so long to measure the flow from my filter. I've read over and over that I need good flow and I understand why. I assumed that having a rate 1700lph filter would be enough even though I expected the actual flow to be a lot less. Recently I added a small external eheim that previously lived in the loft that's rated 650lph.

Is the 10x tank volume rule based on rated or actual flow?

At water change day I decided to measure the flow at the spraybar. I collected 7.2 liters in 1 minute so that makes a flow rate of 432lph which is 25% of the rated flow for the filter.

No wonder I'm battling algae and my crypts keep melting! In my setup the hardscaping creates 2 barriers that run above the substrate for the length of the tank. This complicates my flow issues but at present I have most of the plants gently swaying in a breeze. It must mean that I'm not distributing the co2 properly despite having a yellow drop checker (10 bubbles per sec!!!)

So why 432lph? I have sintered glass in all three chambers, none are full. I've removed the filter floss before measuring flow but there is the eheim "prefilter" or is it post filter sponge. The spray bar is a few feet above the filter. The outflow travels through a sera CO2 reactor and then through an external heater (hydor). I think there is just to much in the way!

I have not measured the flow without the heater and reactor. (I will once I've change the setup)

So my plan is to keep the heater and co2 reactor but drive them with an eheim compact+ 3000 pump installed externally. The pumps rated at 3000lph max so even if I get the same attrition of flow it should provide 750lph and given there will be no filter media in the way the flow will probably be higher.

I'll then use my 2076 as the filter but have nothing installed in the outflow pipe to obstruct flow so that I hope will improve substantially, perhaps even reaching 1000lph.

That should bring me closer to the flow I need.

No wonder I'm pumping co2 into the tank and still having problems. Clive and other wise posters said flow, flow, flow and I just assumed my flow would be adequate from the published rates for the filter. Perhaps the lesson is that if you are having trouble measure your actual flow rate.
 
Fair comment.
I remember some time back doing a similar check on one of my externals, and had a similar conclusion.

Incidentally recently i wanted to check quickly my new eheim 2075 worked, So ran it at little or no head, and completly empty. Well powerful. :thumbup:

Now with everything in, and a floss ready for changing, plus hydor heater, and in line diffuser, :woot: :woot:
Should have bought a bigger one.
 
It depends on so many things. Type/brand of filter, type of media, quantity of media, "packing density" of media, amount of "cloggage" in media, size of hoses, length of hoses, height of hoses, outlets, inlets, blockages, age of filter (probably). The quoted flow rate is often based on having nothing at all attached to or in the filter - even hoses.

At Sparsholt we tested an Eheim Pro II against an AquaOne. The Eheim was far far better at holding it's flow rate, and was much closer to the manufacturers ratings.
 
Even then, the 10x rule was to account for that fact, the filter should be producing roughly 50% or 5x actual turnover. When I had this issue with a tetra I called them up and they agreed it was unacceptable and sent me a new impeller which fixed the matter. Ehiem, a "luxury" brand should really be giving much closer to the expected 50% actual turnover.
 
Hmm, yeah i dont know what my filters output actually is so I supplement with vortech powerheads to do the lions share of turnover. I did read a review comparing eheim 2080 vs Fluval FX5 and the Eheim rated at 1700lph was churning out 1200lph, BUT these were clean new filters, not mucky buggers in dire need of a colonic.

It is a bottom banger, but I guess the primary function of a filter is not turnover, but for a powerhead it is. Right tool for the job so to speak. They make so much money out of us...
 
The filters clean, the pipes are clean, the media trays are 66% full. I'm about to switch things around so I'll let you know what happens when I replace the outflow with a single pipe.
 
Hi all

being saying this for months - but nobody was interested - I have a 2080 which is rated @ 1700 lph actual flow rate is 900 lph - like I have said before: any obstruction - whether it to be filter media inc. sponges within the canister or bio ball with a reactor will slow the return flow of water into the tank.

When members talk about turn over - some people think it means "Filteration" - I will admit I was one of them - a better word would be circulation so a member who has 200 ltr tank required 2000 lph of circulated water, 2 x eheim 2080 would not be enough and I would be very surprised if 2 x Fx5 would be enough, the only option available would be 1 x filter + an additional circulation pump / pumps then the desired circulation can be achieved.

Regards
Paul.
 
tyrophagus said:
So this 10x rule, whats it about? Is it rated flow or actual flow?
Click to expand...


Hi

Again its word terminology - in my eye 10 x rule is as my previous thread reply eg: 100 ltr tank required 1000 lph of circulated water, that 10 x the volume of water within the tank, the bigger the volume of water the more circulation required eg. 750 litre tank requires 7500 plh water circulation.

This why members who have very large tanks have to use 2 filters or add circulation pumps to achieve to 10 x rule.

Regards
paul.
 
tyrophagus said:
Recently I added a small external eheim that previously lived in the loft that's rated 650lph.
At water change day I decided to measure the flow at the spraybar. I collected 7.2 liters in 1 minute so that makes a flow rate of 432lph which is 25% of the rated flow for the filter.
Click to expand...
Err..hey Ty, unless I'm reading the numbers incorrectly, 432 is roughly 66% of 650. This is damned good, because fully loaded filters typically deliver less than 50% of flow rating.

25% of 650LPH would be (0.25)*(650) = 163LPH

tyrophagus said:
Is the 10x tank volume rule based on rated or actual flow?.
Click to expand...
The 10X rule is based on rated flow, NOT actual flow. The 10X rule also takes into account the fact that you typically have 20% less water in the tank than the dimensional volume of the tank. Therefore, to keep it simple, you just multiply the dimensional volume by 10 and seek a total filter RATING of that value.

A 10 gallon tank typically has only 8 gallons of water plus substrate, plus fish plus other junk. But you ignore all that and just use 10 gallons as your basis. This produces a 100 gallon per hour flow rating. This enables you to simply shop for filters by their rating because the manufacturers will never tell you the truth.

So the 10X rule compensates for actual volume and compensates for cheeky filter ratings. The actual flow delivered to the tank when using the 10X rule is somewhere between 3X and 5X the actual water volume per hour. So instead of having to perform all those mental gymnastics of figuring out how much actual water you have and how much the manufacturer has lied to you, all you need to do is to multiply the tank volume by 10 and then get on with your shopping.

If you are low in flow and you want to get a little more performance without buying another filter, then just sacrifice a bit of filtration capacity by removing some more of the media. If you are only very lightly stocked then this is not a big deal. Filter media causes tremendous hydrodynamic drag and lowers the throughput via this friction. You can substitute sponges for the sintered glass media in order to improve your flow.

Cheers,
 
I think he means 432lph out of 1700lph of the Pro3e. Don't forget to check if the Pro3e is set to "wavemaker" mode. My friend has a Pro3e and his otos actually get stuck to the inlet due to its pulling power.
 
I havnt read it all but I know the electronic filters from Eheim is critically with dirty tubes and stuff like that, also if you connect a co2 reactor to those filters, it will tell you that it needs to be cleaned and automaticly drops the flow (for some weird reason I dont know why).
One of my friends told me this.
 
In my original post I said I added a 2nd filter that had a rated flow of 650lph. Probably best I'd left that out as its confusing. I'm talking about 432lph from the Eheim Pro3e which has a rated flow of 1700lph.

Well I've ditched the 650lph filter. I've removed all obstructions (co2/heater) except for the sintered glass media from the eheim Pro3e which is set to manual mode (ie max output - no programs altering flow). I have not got round to measuring its flow but when I do I'll update this post.

I installed an eheim compact+ 3000 power head externally that pumps through the CO2 reactor and then the external heater and into the main spraybar. I have it set at 3000lph (can be turned down to reduce flow) and my eheim filter is set at 1700lph.

So for a 180l tank it sounds like overkill as I was aiming for 10x actual flow :lol: I can actually reduce the filer and the powerheads flow if needs be

I must say that for the first time it appears there is flow in the back bottom corners. My fish seem to be coping fine.

Hopefully I'll get on top of the BBA and staghorn and cladphora. I just have to get the plants as healthy as possible!

Oddly I've been able to reduce my co2 from 10 bubbles per sec to 5 bubbles per sec and still keep the drop checker yellow.
 
OK, fair enough, I figured there must have been a good explanation. :crazy:

tyrophagus said:
Oddly I've been able to reduce my co2 from 10 bubbles per sec to 5 bubbles per sec and still keep the drop checker yellow.
Click to expand...
But why would you find this odd mate? This is exactly what we have been trying to drill into peoples heads for what seems like a generation. High flow mixes and dissolves the gas more thoroughly, reduces boundary layer thickness, increases the gas transport across the thinner boundary layer and reduces stagnation. Higher flow also pulls waste products away from the plant.

Increasing the efficiency of the injection lowers the consumption from your cylinder while improving plant access to CO2. The same can be said of nutrients. By improving flow/distribution, your reported injection rate adjustment will have increased deliverable nutrient/CO2 efficiency by approximately 100%. Plant nutrient/Co2uptake rates should now improve and any deficiency related symptoms should now be on the decline. By lowering the injection rate you now have given the fish more "breathing room" so they are less likely to suffer blood acidosis. :angelic:

Cheers,
 
Thanks Clive. I thought it odd because I believed the increased surface agitation would drive off more gas so I'd lose CO2 faster. I suppose that could still happen but I'm dissolving more CO2 which makes up for any increased loss.

I've posted a video of the effect of the flow on the tank in my journal.

Thanks for all your advice, I'm sure I'll get there in the end.

Flyfisherman said:
When members talk about turn over - some people think it means "Filteration" - I will admit I was one of them - a better word would be circulation so a member who has 200 ltr tank required 2000 lph of circulated water, 2 x eheim 2080 would not be enough and I would be very surprised if 2 x Fx5 would be enough, the only option available would be 1 x filter + an additional circulation pump / pumps then the desired circulation can be achieved.
Click to expand...

I could not agree more Paul. The penny dropped for me while mulling over how to increase the flow with no space for a bigger filter. I had used an internal power head to improve flow (vortech mp10) but it actually interfered with optimum flow pattern created by the spraybars so it had to go. I needed a more powerful pump to drive the spraybar, I didn't need a bigger filter.

Until I considered an external pump I never even realised "power heads" could live outside of the water. Once I started to look on the forum I found loads of members use external pumps. We need good filtration but good filtration does not necessarily equate to good flow.
 
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