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Discussion Starter · #1 ·
I'm converting a reef tank to a planted tank. It was a standalone style tank with only the water flow through the rock for filtration.

Rather than using a cannister or HOB filter, can I just use flow in a planted tank as filtration? Among other things I have some rough surfaced sandstone I want to add that bacteria can cling to. I could even use some fresh homemade live rock.

What sort of flow should I go for? The tank is set up for 15 times flow.
 

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Joel, the concept's interesting, but I doubt that it would be successful. In a freshwater tank, the filtration is based on providing as much surface area as possible for the bacteria that you're correctly speaking about. But, the rock that is suitable for a freshwater tank doesn't offer that in such a way as to make it nearly as effective as the kinds of filter medium that are widely available these days. That having been said, I suppose that if you're extremely attentive to the nitrate levels that you have in your tank, which would require very, very frequent testing...and you also keep your phosphates controlled so that they are in sync with the nitrate levels, you might have some success. But maintaining a levels of the kind necessary to avoid algae breakouts wouldn't be simple. Doing what you're contemplating without fish in the tank may make success more likely because phosphates could be controlled much more accurately without fish. As for your question, though, the whole issue isn't as critical in a planted freshwater tank as it is in a reef (I have a mature 120-gallon reef, too.) In a freshwater planted tank, IMO, flow is necessary but not nearly as the same level as in a reef. So long as you have enough flow to keep CO2 dispersed evenly throughout the tank and the plants aren't blown over on their sides, you'd be fine.
 

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Discussion Starter · #3 ·
Hmm. I can leave one korallia for 8x/hr flow and may be able to aim it down one side to produce a loop flow around the tank with minimal surface agitation. I could place a couple of pieces of thoroughly porous rock within that flow.

Would bacteria attach to driftwood? I have a nice piece of hardwood with a splitting surface... and I plan to keep the plants growing ahead of the bioload.

Still, (if absolutely necessary) I have an eheim cannister that would give 1x/hr on this tank or a mini internal sponge cartridge type that would give half of that (or I could use a couple of those).
 

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Bacteria would "attach" to every surface in the tank after it has the time to do that. But, again, driftwood doesn't afford that much surface area that you'd be able to control the nitrates. Now, I should point out that in a planted tank, some level of nitrates is essential. It's one of the basis "macro" fertilizers that is necessary for the plants that you keep receive their nutrition. The level of nitrates that you maintain would depend on other factors that are at play...the amount of lighting and CO2 that are available. If you put very high light on the tank and apply good levels of CO2, then the amount of nitrates that your water would have if you keep fish in the tank and refrain from using a canister or hang-on filter (as you contemplate) you may (or may not) have nitrate levels that are sufficient for your plants. Indeed it would, IMO, fluctuate radically from day to day. You'd have to constantly test to make sure that the nitrate levels don't drop below their necessary levels and also vis-a-vis the phosphate levels in the tank. You'd have to be adjusting your nitrate levels with additives, I believe, on a daily basis, or risk a constant battle with various kinds of unwanted algae.

Joel, if I may ask...what's your reluctance to use the canister filter?
 

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Discussion Starter · #5 ·
Joel, if I may ask...what's your reluctance to use the canister filter?
For one thing, I like the 'self contained' paradigm...granted, it isn't enough of an excuse. I also dislike cannister maintenance because every time I do I seem to have a new problem, whether it's an airlock and I can't get it started again or I end up losing some of the media or there's a new leak and I have to rebuild or use silicone on the lid, or there's a new rattle in the filter after I reassemble it or something.
 

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Biological filtration isn't that much a concern in a planted tank (that is, not a HEAVILY planted tank) since the plants are extremely good biofilters.

The issue really is mechanical filtration. Planted tanks produce quite a bit of debris. And debris buildup = algae issues.

You could stick with powerheads, but I'd put good sponge prefilters on them all and you'll need to make sure to keep them clean. Plus try to be as pro-active with your pruning as possible to keep up with dead leaves.

Sounds like you need a better brand of canister filter. Though I know Eheims and Renas cost a pretty penny in Oz...
 

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Biological filtration isn't that much a concern in a planted tank (that is, not a HEAVILY planted tank) since the plants are extremely good biofilters.
Conceptually, I agree, but in reality it's not so easy. I use estimative index dosing and found that the plants in my heavily planted tank were not getting enough nitrates so I had to go up to the next size-range of tanks in order to provide the nitrates that the plants need. I've seen very experienced recommendations that following EI-dosing doesn't require testing very frequently, but I've found differently. I can only imagine trying to achieve the needed nitrate/phosphate balance in an unfiltered tank without testing. That's not my cup of tea.

The issue really is mechanical filtration. Planted tanks produce quite a bit of debris. And debris buildup = algae issues.
While I wouldn't go so far as to call it "the" issue, it is certainly a good point. One, that addresses the phosphate issue and makes a grip on nitrates all the more poignant in the question of whether or not a canister (or some other similar) filter should be used on a planted tank.

Sounds like you need a better brand of canister filter. Though I know Eheims and Renas cost a pretty penny in Oz...
Joel's already got an Eheim sitting there just waiting to be used. But, IMO, for a good deal more than the 1-hour that's contemplated.
 

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I can't imagine running a really high tech tank without a good filtration system. High tech really means "fast"- and the faster plants are growing, the more fert dosing, and waste output...

In a low tech tank it would be much easier to get by with minimal (if any) fert dosing. And sponge prefilters on powerheads as I proposed would be exceptional biofilters in addition to mechanical.

Those plus the Eheim for mechanical/chemical would be perfect. If that's the leaking filter then it's probably just time to replace the O-rings.
 

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If you don't have fish and, of course, don't put fishfood into the tank because you don't have any fish, then filtration is more important from the mechanical side than the chemical side. With no addition of fish food and the process of fish eating it and the consequent waste, there'd be no phosphate/nitrate introduced to the tank for the plants to consume. So, you'd have to put the ferts in. But, even still, without the fish, like laurel mentioned, there's dropped leaves, etc. that require mechanical filtration.
 

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Discussion Starter · #11 ·
There is not enough info here to answer the question.
I would like to go low tech (ie attempt to involve enough plants to cope with the bioload). I plan to use a medium bioload (a little less than what you'd call just right on a conventional non-planted tank). I have some angels, loaches and plecos from another tank to start. The tank is a 6' 125g. There is a 70W metal hailde above the centre and I may put a 2' flouro on either side of it. I plan to use a fertile substrate and I want to add ferts as required rather than using EI.

BTW, o-rings on the eheim would go a long way :)
 

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I would like to go low tech (ie attempt to involve enough plants to cope with the bioload). I plan to use a medium bioload (a little less than what you'd call just right on a conventional non-planted tank). I have some angels, loaches and plecos from another tank to start. The tank is a 6' 125g. There is a 70W metal hailde above the centre and I may put a 2' flouro on either side of it. I plan to use a fertile substrate and I want to add ferts as required rather than using EI.

BTW, o-rings on the eheim would go a long way :)
I think a couple of angels and a few loaches would be reasonable for a 125 with minimal filtration. I think the canister/coralia would give you some buffer on your bioload and supply the current that your loaches and pleco would appreciate.
 
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