What’s the optimum GPH filter flow for a planted tank?

[Jeremy S]

I was wondering how many times the aquarium water should go through the filter per hour. With cichlid tanks the recommendation is about 10 times per hour but isn’t that too much for a planted tank? I also heard that you can have too much biological filtration on a planted tank and if you do it will use up most of the nutrients. If that’s true should you use mostly mechanical filtration? Thanks.

[RTR]

There is a phenomenon known as boundry layer effect, which involves stagnation near surfaces unless overpowered by breezes or currents. You need enougn current to minimize boundry layer effect, but not so much as to flatten the plants against the sides or substrate. ;) Anything in-between is great.

IMHO, the bit about "biofiltration straving the plants" is either myth or bull feathers, depending on personal attitude. I observe exactly the opposite effect, as does everyone I know who has tested it. Don't pass that on as fact unless you can back it up. Diana Waldstad is not fact, she discusses it but never did any testing. Mental exercise is not fact. Dry-lab proves nothing and if passed on as this bit of pseudocience is commonly, can lead to myth and leading people astray. Testing provides evidence of reality and can lead to fact.

[Jeremy S]

I have an eheim ECCO 2235 and its only 185 GPH if you have nothing connected to it but I have a reactor 1000 and two 90 degree curves so that cuts down on the filter flow a lot. It looks like the output is only around 100 GPH and whenever I feed the fish the water gets dirty and it takes about an hour for it to settle down. So I was wondering if I should upgrade to an eheim pro II. It would clean the water better and give me better CO2 diffusion. Do you think it’s worth the money?

[Cearbhaill]

I'm using an Eheim 2026 as the only filter on a planted 90 gallon.
Initially I found the circulation to be less than adequate but a few moments adjusting the spraybar fixed that pretty quickly. The most minute adjustments really change the flow pattern inside the tank a lot. My output just gently ripples the surface but then takes a course that insures there are no dead spots.

They're pricey that's true. But they're also silent, easy to use, and dependable. If you do decide to go with a Pro II I would definitely recommend that you get the prefilter attachment as well. If you simply rinse the prefilter once a week or so (they lift right out easy as pie) then you'll need to get into the cannister itself much less frequently.

[The Gipper]

How did you adjust the spraybar ti increase circulation?

[Cearbhaill]

Just rotate the spraybar itself to change the direction that the water sprays out.
I have it directed at a bit of an angle towards the surface- enough to gently ripple without any splash or agitation.

[Jeremy S]

Does the eheim pro II come with a spray bar or do you have to get that separately? Cearbhaill, do you have any trouble keeping the water clean with your eheim? I do weakly water changes but I still have trouble with the water getting dirty when the fish are active.

[Slappy*McFish]

Try vacuuming the surface of your gravel. My loaches do the same in my planted tank whenever I feed them. They really stir up quite a bit of detritus from the substrate.

[Cearbhaill]

Does the eheim pro II come with a spray bar or do you have to get that separately? Cearbhaill, do you have any trouble keeping the water clean with your eheim? I do weakly water changes but I still have trouble with the water getting dirty when the fish are active.
The spray bar comes with the filter.
My water quality stays pretty decent but I have a relatively low fish load and I don't feed them too much. I used to get into seeing full little bellies after every meal but once I got over that things got much easier to maintain.

[anonapersona]

I can't recall where that came from, so I guess that makes it a rumor.

[RTR]

I'm not sure it is possible or practical to set a GPH for any given tank. The arrangement, for how the return(s) are set, whether the spray bar(s) are standard or customized, the fish stock, where the barrier plants are (large swords, stands of Val, etc.), there are just too many variables. You don't want dead spots if you can manage to get rid of them, nor do you want the plants flattened by current. I pretty much cuatomize every setup, and commonly re-do a couple of times as the plantings mature.

As example, in this room I have a 55, with 41 gallons actual water volume. It is filtered by an Eheim 2213 (~100 GPH), and Eheim 2008 (~80 GPH) and an Eheim 2010 (~130 GPH) (both internals turned all the way up), so about 310 GPH total or about 5.6x turnovers of nominal volume.

Also in this room I have a 29 with ~23 gallons actual volume. It is filtered by an Eheim 2211 (~80 GPH) and 2 each Fluval 2s (~100 GPH each) , so about 280 GPH or about 9.6x turnovers per hour.

That sounds like a huge differenece between the two tanks, but in reality, while the smaller tank has a little bit more current, it is not that great a difference.

There, anaona, you have at least one example that is in the range of 5x turnover - even if the other is almost double that.