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Discussion Starter · #1 ·
Hi guys,


I am currently planning to replace my 2xWhisper EX70 HOB filter with an Eheim canister filter for my 55 gallon planted tank for two main reasons:
1. More space for my plants
2. Integrate inline heater (add more space for my plants)
3. Inject CO2 directly to the filter


My question is the GPH. I know that the recommended flow rate is 5x-10x the tank capacity for a planted tank. Currently, I have ~600GPH water movement with my two HOB filter.


When I look on the Eheim website, the one rated for a 66Gallon tank is only rated at 116GPH. Does the same rule apply with a canister filter? Does this mean I have to purchase a canister filter rated for 300G tank?!


Felix C.
 

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You have two filters rated at 45-70 each and replace with one filter rated at 66 max you will have less filtration and water movement. You will also have more media volume, cleaner look, pull equipment out of the tank. HOB's are actually quite effective and people undersell them.

Are you happy with your current level of filtration? It seems you main motives are not related to under performing filters, just ancillary reasons. I used one of those Tetra filters because it was free with an aquarium I bought. They are cheaply made but they are not messing around on water flow. If you are unwilling to accept a downgrade in water turnover you should probably consider a larger canister filter.

You should also realize the putting a heater and reactor in the plumbing could lower GPH even more.
 

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I'm pretty sure the gph rating from Eheim is rated without head pressure (or without media or something). I've tested full eheim canisters, though slightly used, and they do not meet their rating. I would definitely over do it with them canister. You can always diffuse it a little if it adds to much flow.
 

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Go with the turn over rule. Don't believe the manufacturer's "this filter is rated for X gallon tank size".

Usually it's recommended to have a x5-x7 turn over rate. I prefer to recommend at least a x7 turn over rate when going by the listed specs GPH.

The listed GPH is usually rated when the pump operating at level headheight and no obstructions. So when you factor in head height, obstructions from media, etc. the actual/realistic GPH is much lower than the rated GPH when situated for our typical aquarium use. This is more of a factor when dealing with filter pumps that operate with headheight, such as canisters or sumps that are below the tank since they have to pump water up higher. Filters/pumps that operate at level headheight, such HOB's, interal submersible filters, etc., just suck in and push out water, no need to really lift any water, so their actual GPH is closer to the rated, but there still is some GPH reducing factors such as obstructions from the media we use.

From what I have read, the difference in rated GPH depends on the brand/filter. For instance, SunSun canisters actual GPH may be closer to half the rated GPH, where as many Eheim's and Fluval's actual GPH is closer to their rated GPH ("GPH holds more true", hear the reviews of them being powerful outflows even though they have lower rated GPH than SunSun's). That's just from what I have heard, I haven't tested myself, but again, there are many factors that affect GPH, and we aren't sure if reviewers have factored those in (I give them the benefit of the doubt though. maybe Eheim and Fluval rate their filters in more realistic settings?).

I'm a fan of overfiltration, so the more the merrier as long as the current within the tank isn't very chaotic for the tank inhabitants.

The higher turn over rate, the faster/more times any wastes get passed through the filter, keeping wastes addressed sooner, which is a plus. The more GPH does help with circulation as well.

Those are just a preference though. I am not familiar with Eheim filters and their GPH ratings, but I am sure plenty of people use this or that canister filter that only equates to x4 or less turn over rate and have no issues. Bioload does play a factor though. Look at reviews or post another thread (with a title like "which Eheim filter for 55 gallon tank") or look up already asked and answered threads regarding which Eheim canister for a 55 gallon tank. By the way, I've heard there are rebranded Eheim canister filters (Ecco series?) under the Nat Geo brand (sold at PetCo/Petsmart), so they should be a good bit cheaper.

With all that said, I have used a SunSun 304B (rated 525 GPH, but actual is significantly less, closer to half that maybe) on a 55 gallon tank and it can do the job. It does lack a bit in outlet flow, and so you might desire to add a additional circulation pump/powerhead in the tank to circulate within the tank more. But yeah, just say actual GPH is 250 GPH and it can handle biological filtration perfectly fine (and my tank is overstocked). I haven't used Eheim/Fluval canisters so I can't comment on their actual GPH, so it's tough for me to say which filter/rated GPH of those brand canisters would work, which is why I recommend asking others who do/have used them, or look up already given reviews/experiences.
 

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Keep in mind that manufacturer claim of filter supporting xx gallons said nothing about planted tank. That filter, at that level of flow, will be able to mechanically and biologically handle that tank size. However will the flow be enough to provide good circulation for plant? Probably not. I find the best solution is to not rely on cannister for flow as it vary alot depending on how dirty your can is. Use power head to ensure consistent circulation.
 

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Discussion Starter · #7 ·
Thanks for the quick feedback guys. Now I'm a little hesitant to go with the canister route as I'm happy with the current filtration GPH and the even water flow on both sides of the tank.

I was only planning for aesthetics for the most part, and spending an extra $200 only to put another power head in doesn't seem justifiable. Although the quiet factor and the less evaporation due to less surface exposure is still enticing. Decisions decisions.
 

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Thanks for the quick feedback guys. Now I'm a little hesitant to go with the canister route as I'm happy with the current filtration GPH and the even water flow on both sides of the tank.

I was only planning for aesthetics for the most part, and spending an extra $200 only to put another power head in doesn't seem justifiable. Although the quiet factor and the less evaporation due to less surface exposure is still enticing. Decisions decisions.
The other nice thing about cannister is you can put header + co2 atomizer outside of the tank.
 

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5-10gph is a decent rule for total advertised filter capacity per gallon of tank water.

Another rule of thumb is that expensive filters actually move 1.5 to 2.0 X the water of cheap filters (that's one of the reasons they're more expensive). Eheims are at the top of the list, and SunSuns are at the bottom. Which is not to say that SunSuns are crap. They're amazingly, almost unbelievably, reliable for such a cheap filter. With the understanding that all filters overstate their efficiency, SunSuns overstate it more than most.

Avoid HOB's if you can. If you can't avoid them, go with AquaClears. There really isn't a substitute.
 

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Cannister flow rate is only as good as how clean you can keep them. My eheim eco flow rate by half every two weeks forcing me to clean it out thank to the poop machines and the clay from ohko stones.
 

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Discussion Starter · #11 ·
Lol, my biggest poop machine are the three dwarf puffers... and it's not that much.

I have been deciding on Aquaclear HOB filter, but my water quality is clean... and don't want to go from HOB to HOB.
Looks like Eheim may win my heart over. For those Eheim owners, I need some advice on:

1. What do you put into the canister (I hear people omit carbon for dosing planted tanks)
2. Do you have a good video link that shows plumbing CO2 line into the canister filter. I'm not that mechanically savvy, but super anal regarding asthetics.

I currently have a Suntek solenoid with 24Oz paintball tank going into drop checker then into a cheap Fluval diffusor... I think the diffusor is losing a lot of CO2 in the process, as I see one large bubble coming out every two seconds.

Thanks guys! Can't wait to put the inline heater and the CO2 with the canister filter. Does this mean no diffusor is needed?
 
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