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Hi there,

I was wondering how many time should the tank volume turnover in a heavily planted tank turn over? and when calculating this do i include the sump volume as well as the tank volume?

Regards Darren
 

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I've asked this questions several times in different ways and never got an answer. On another forum I was reading about a tank Tom Barr set up a 180gal with a 2000 gph maxi jet. In addition his filters are 2 sumps. (I believe it's 2) It's doing beautifully. I think that was the most turnover I've come across on the forums. It was so much it stuck in my brain! I'd like to see what others tell you.
 

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We've discussed this at UKAPS and we reckon to go for about 10 times turnover. Personally I've got a Juwel tank with a large internal filter that filters tha tank about 3.5 times an hour and a Hydor Koralia that turns the tank over just over 8 times an hour. So about 11.5 overall in theory. Once the media is in the filters though and they've been running for a while they lose a lot of this. Aiming for 10 times probably means you're about 5-7 times turnover.
 

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There is no real answer IMO since every tank is different. Most I think would shoot for a turnover between 3 and 6 (effective not on the filter box) times per hour. Your really just need some flow in a well planted tank since the filter will actually be a small part of the filtration. I have 3 tanks that are runing beautifully on 1 turnover per hour. There is also theory the process of biological filtration is more efficient at a slower flow rate over the same amount of media.
 

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I have noticed that Tom Barr is now advocating lots and lots of flow in the tank, but that isn't like turnover, which is a terminology for filters, where water leaves the tank and returns. The advent of in-tank pumps or powerheads like the Koralia or the powerheads modified to use model boat propellers to move water changes the whole way of thinking about in-tank flow. It is one thing to have a half inch diameter pipe blasting 1000 gallons per hour in the tank, but an entirely different thing to have a little propeller moving a 1000 gallons per hour in a large diameter propeller wake. I think the goal is to have all of the water in the tank always moving, as if it were a river.
 

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I once read that 3-4 times per hour was ideal (Aquarium Atlas by Riehl and Baensch, p.57).

I've gone with a 6 times per hour rule when I had fish-only tanks and that kept the tanks clean. The exception would be for large messy fish (like Oscars).

But in a planted tank, your main focus is on flow to keep the water circulated evenly throughout the tank (like hoppy mentioned with the koralia, etc...). I think that turnover per hour is less important because the plants in a heavily planted tank are a filter themselves. You'll get the turn-over you need with most any filter (within reason) if you focus on the current that your fish want and the circulation you plants need, in my opinion.

-Dave
 

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I had lots of flow in the tank from powerheads and all, it seemed to annoy my plants more than anything. The fish loved it though, very much.

If turnover is the same question as "How many times should the tank volume be cleaned in an hour?" Then I would go with ten. I just upgraded my filter and it's at 10 times an hour now, the water is so clear I may drink it. There is still a lot of movement, even surface turbulence, but that's what really happens in nature.
 

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I really don't think you need flow in the sense that you see the water actually moving that much. In most of our tanks that are 2 to 4 feet big, how much flow do you need to move dissolved ferts and co2 around. If your talking about algae control, I haven't seen any proof that algae grows more in areas with less flow. I've seen algae on people's tank right inside the co2 diffusor and right inside their return tubes. I have to believe there is flow there. Look at a pond outside. How much algae grows right on the rocks in a waterfall. There isn't one answer. It depends on your maintenance habits and other variables. Hobby why does Barr recommend alot of flow? By the way in terms of biological filtration this is a direct quote from Eheim:

"EHEIM filters concentrate in biological filtration. If the flow is too hi, the water will not have enough contact time with the bacteria, therefore you will not have optimum biological filtration".
 

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This is a very interesting topic. I just moved my spray bar out of my tank to stop disturbing plants. When I read takashi amano's book I remeber how he said. " success is the awareness of things other people take for granted". And on his tanks he just seems to have one filter. But I have in the past seen that water flow can help control algae and keep things clear. I also respect every thing tom barr has to say and if he is promoting water movement I'm sure there is more to it than what I think. I would like to see some hard core facts on the issue. One my 29 gallon I have a fluval 205, so my tank cycles about 4 times per hour. I some times wish I had gotten a little bigger filter.
 

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QUOTE=houseofcards;407432]I really don't think you need flow in the sense that you see the water actually moving that much. In most of our tanks that are 2 to 4 feet big, how much flow do you need to move dissolved ferts and co2 around. If your talking about algae control, I haven't seen any proof that algae grows more in areas with less flow. I've seen algae on people's tank right inside the co2 diffusor and right inside their return tubes. I have to believe there is flow there. Look at a pond outside. How much algae grows right on the rocks in a waterfall. There isn't one answer. It depends on your maintenance habits and other variables. Hobby why does Barr recommend alot of flow? By the way in terms of biological filtration this is a direct quote from Eheim:

Hi Houseofcards, I have one comment to make regarding why you see algae forming on the inside walls of plumbing in filter tubing that that is a phenomenon called "wall drag" or "fluid slip". Where as in a pipe there are two flow rates actually occurring. One is in the centre of the pipe which is what we all see and preceive as the only flow. The other is caused by the "wall drag" this link my describe it better than I can;

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=14761

essentially what happens is on the inside of the pipes or tubes there are microscopic grooves where water traveling on the outside of the diameter of the water column get trapped in these grooves. The water that is on the inside track simply just slides over top the trapped water. Thus creating a wonderful little home for algae grow.
I personally believe that flow is required in an aquarium no matter what the nature of it (fish only, planted, or reef). The same basic principals or envolved, and that is we want to remove debris and toxic wastes from the inhabitants.
On the other hand too much direct flow could work against the aquarium environment where the plants cannot "catch" their food from the water column. So that leaves us with a nice gentle dispersed flow throughout the tank via a spray bar or multiple water return lines in order to get the job done. That's not too say that it is an absolute must have, after all if it works for some to have very little flow than that's all that really matters.

I hope this as shed a little light onto the subject.

Cheers to all!
 

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Klaus777 that actually makes alot of sense and if that is true I think further illustrates my point. That algae will grow in high flow areas. These microscopic pores would also exist on wood, rock, hardscape and slow growing plants making increased flow useless in terms of algae control. The eheim statement about flow and biological filtration as well the statement you sourced :

"On the other hand too much direct flow could work against the aquarium environment where the plants cannot "catch" their food from the water column. So that leaves us with a nice gentle dispersed flow throughout the tank via a spray bar or multiple water return lines in order to get the job done. That's not too say that it is an absolute must have, after all if it works for some to have very little flow than that's all that really matters" makes the case that too much flow can be an issue in certain situations.'

Don't get me wrong, I believe in flow, I just can't imagine how much you need in a glass box 2 to 4 feet big.
 

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I personally haven't read anything that has any theories on the amount of flow in a planted tank. All I know is the only turnover I have in my tank is from my filter which gives 8.57 turns per hour. It is a HOB so the flow is dispersed but really only gives enough flow for what I like on one side of the tank. In Duzzy's case he wants to use a sump so the question of flow wouldn't really matter since the return pump is going to dictate what the flow rate is, which will be also completely adjustable by plumbing a "dump gate" off the return line back into the sump. And if multiple return lines or spray bars this would greatly reduce target flow areas.
 

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The flow at the surface of all leaves is essential zero. Those surfaces are in a boundary layer, where the flow velocity is zero (ideally). So, leaves have no problem "catching" their nutrients. That very thin layer of water that is in contact with the leaf surface very quickly runs out of nutrients, giving a gradient of nutrient concentation tht goes from near zero at the leaf surface to average tank water concentration not too far away. We depend on the circulation in the tank to quickly replace the partially depleted water near the leaf with more water that does have nutrients in it.

Flow isn't what stops algae. We all probably see algae growing very well on our spraybars and other high flow hardscape elements. What stops the algae is the rapidly growing plants in the tank, which use up ammonia as soon as it is supplied by fish poop. But, without good water circulation the leaves don't get supplied with that ammonia immediately, and the leaves don't get a good continuous supply of the basic nutrients they need to grow rapidly.

Again, good flow isn't a half inch diameter high velocity blast of water. It is continuous water movement at a much slower velocity all over the tank.

I'm willing to bet that one year from now, there will be a different consensus about what is the best flow in a planted tank. In this hobby virtually none of our "rules" stay the same longer than a year. It's almost like chasing your tail.
 

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Well put Hoppy, I have seen many rules change and seen beginners struggle with old books and abandoned ideas. It would be nice to have some hard core evidence on this.
 

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Of course some flow is needed, I just don't think you need that much to have plants grow. And I'm sure there's quite a wide acceptable range in terms of plant growth, bio-filtration, etc., depending on one's setup. BTW how do the plants in a filterless nano setup grow. Is the flow that is created once a week during a WC enough? If flow is needed then that must be enough to provide them with nutrients. Or is it the small fish or shrimp swiming around enough to move nutrient rich water over the leaves. Either way the plants are surviving with almost no flow and certainly not flow on a regular basis.
 

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One thing that deserves some attention is to supply enough flow to keep detritus suspended in the water column. If you can do that, the canister filter will be able to remove it. If the gunk settles to the bottom, it's stuck there forever until you do a gravel vac.

One thing I've really noticed recently is the need to keep debris off of the plants. Algae have a hard time forming on healthy, quickly growing plants. They'll quickly set up shop on a small mass of rotting leaves or on a clump of stray debris.
 

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Of course some flow is needed, I just don't think you need that much to have plants grow. And I'm sure there's quite a wide acceptable range in terms of plant growth, bio-filtration, etc., depending on one's setup. BTW how do the plants in a filterless nano setup grow. Is the flow that is created once a week during a WC enough? If flow is needed then that must be enough to provide them with nutrients. Or is it the small fish or shrimp swiming around enough to move nutrient rich water over the leaves. Either way the plants are surviving with almost no flow and certainly not flow on a regular basis.
Growing aquatic plants doesn't require a fixed, immutable set of conditions, or else the plants all die over night. I am a good example of someone who can grow plants under far from ideal conditions. You can grow plants with just fish poop as fertilizer, with no filtration, with low light, with algae all over the place, etc. What we are trying to do is grow them well, healthy and vigorous. That is what requires the good conditions, including good water circulation. As I see it, the real dispute is over what constitutes good water circulation. That issue is still up in the air. But, the trend seems to be towards a lot more circulation than we used to see in planted tanks.

We went through something similar with light intensity. We kept learning that we needed a lot more light than we were used to. So, people kept adding more light. Eventually we reached the point where we were using more light than we needed and causing as many problems as we were preventing. Perhaps water circulation will follow that path too.
 
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