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Discussion Starter #1
You all are in trouble now. I am back on the Weekly discussion thread again. so listen up. :D

i hope to do a new one very Monday. i have read the New Years Resolution thread and will pick from that in the beginning, but feel free to PM me any ideas you have for future topics.

OK, back to the task at hand. let us talk about flow. what kind of flow is good, how much flow is necessary, can flow be adapted for various places in the tank? why do we need flow, what are our limitations on flow?

this should be a good start.

G~
 

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spaceman spiff
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random, anywhere from 10x-100x, yes, to remove and distribute nutrients throughout the tank, hardware we use trying to recreate nature.

That good?

I think it's partially my fault that this topic popped up, but that's fine by me. In almost all scenarios, you need good random flow to mimic nature as best as you can and support the critters you're trying to keep in the tank. Amount of flow can vary greatly, and is more dependent on what you're keeping in the tank and the style of tank you're keeping. I think the biggest drawback for me was the point sources that I had. Neglecting the marginal flow I get on my return pump, I had only 2 other sources that provided 90% of the flow in my tank (though granted, they were Tunze 6100s). Because I keep a barebottom system designed to pull out wastes as quickly as possible, my flow was inadequate and I was getting build up on the floor. So, I added another pair of pumps that shoot across the bottom of the tank, thereby eliminating the issues I was having.

But again, these were drawbacks of the hardware, and honestly I could have overcome them with maintenance (through more concentrated efforts of siphoning the piles of waste). I had plenty of flow in the tank for all intents and purposes, but I was looking to increase the efficiency of nutrient import/export of the overall system.
 

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Carpe Noctem
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How about random consistency:funny: Like that makes sense!

but seriously I want to consistently use the flow to up heave detritus and get it into my drains and to the skimmer or at least the bottom of the sump that I vacuum out every week. From there giving enough flow to everything is the next important and probably where I leave off. I'm around 32x turn over and it may be on the light side, but right now I'm happy with it. I bet as things grow in I will need more, or perhaps the same flow delivered in a different manner:idea:
 

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Reef Nut
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Does it have to be random? I know the ocean is random and we are trying to 'imitate' the corals natural environment. I also know from experience that high, consistent, non-random flow will cause corals to grow in a particular direction based on where the flow is coming from, but what else are reasons? I also can't figure out how to get enough flow to keep all of the detritus in suspension. I have about 30x (3 K3's and a sea swirl on my 500gph return) in my bb primarly sps tank, but I still get build up on some of the rocks that only comes off when I turkey baste them weekly w/ my water changes. But I can't figure out where to put another power head that won't blow the flesh right off the corals. Also, don't the fish need a place where they aren't constantly being battered by high flow?
 

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i think "chaotic" is a better descriptor than "random".

to me, you need as much flow as necessary to keep particulate in suspension. when particulate settles is when we get into trouble.

with sparse aquascaping, you can get by with minimal flow. the object is to minimize dead spots. i personally use two vortechs set on opposing reef crest mode, plus a wavebox which is constantly rocking the entire water column. i feel this is sufficient chaotic flow for my aquascaping. i have two places where minimal detritis is collecting, but i can easily siphon those spots - though i may add some small powerheads to blast those spots in the future.
 

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Perfeshunal Hikk
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You all are in trouble now. I am back on the Weekly discussion thread again. so listen up. :D

i hope to do a new one very Monday. i have read the New Years Resolution thread and will pick from that in the beginning, but feel free to PM me any ideas you have for future topics.

OK, back to the task at hand. let us talk about flow. what kind of flow is good, how much flow is necessary, can flow be adapted for various places in the tank? why do we need flow, what are our limitations on flow?

this should be a good start.

G~
My flow is linoleum (read it with an Alabama accent).

Good to see a weekly discussion thread starting back up regularly. But, keep it bi-weekly to give us slow people time to keep up. Depending on the topic. Some can be covered in a week, some can't.

One thing with the list. Last fall there was a thread (I can find it later if needed) where I asked what topic people wanted, zoooxanthellae was the #1 request. I don't know if thats in the new years thread or not.

OK, back to flow in a tank. How much flow you need in the tank depends on other things. Inhabitants, substrate, rockwork. SPS need more flow than softies do. A SB tank can't have the same amount of flow on the bottom as a bare bottom tank.

As for random and chaos, the worlds oceans are randomized chaotic order. There is order to the random and chaos. But, to be quite frank, you can't put random flow in a tank. It will have order to it no matter what you do so using the word "random" isn't the right word.

Chaotic flow isn't good either. You have to have a good flow pattern that directs things in the order you want them to flow. 200,000 gph in a tank won't do its job if its all pushing away from the drains. There HAS to be order to the flow in the tank. Otherwise its just wasted water movement.
 

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Discussion Starter #8
what is flow, are we talking velocity or volume?

is the flow really random on the reef? think micro/macro, are they different?

why do SPS need more flow than softies?

chaotic is a good descriptor, i could not care less which one we decide on, the reasoning is still the same.

G~
 

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Perfeshunal Hikk
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When describing flow, you have to use both velocity and volume as they are both part of it.

Is the flow on a reef random? Yes and no. There is no way to predict what direction the water will be flowing at any given time but over the long term, there is a predictable pattern to flow on the reefs.

Personally, I think its a myth that softies need less flow but I will let someone else have that one for now.

Chaotic waterflow in a closed system is bad.
 

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Reef Nut
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The reason I thnk softies need less is that in my experience the leathers, frogspawn, muchrooms, xenia, candy canes, and sea fan I have had shrivel up and won't open in the kind of flow I have on my sps. And, conversly, the sps don't get anywhere near as good polyp extension if they don't have strong flow. ahowever, do they really need all that flow to thrive? The ones in less flow don't seem to grow as well.
 

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I think a little of it deals with velocity, but you can accomplish a lot by getting the volume of water moving. This is the principle behind the gyre type systems. They use some velocity in the beginning to start moving the water volume, but then that can be tuned down as the entire volume of the tank is in motion and self perpetuates the wave. The randomness in that case comes from the body of water hitting the live rock and corals and being diverted accordingly.

I would like to experiment with a system like that someday, but for now I am relegated to my sand bottom and powerheads. ;)
 

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What about in the sump? Is flow necessary in a sump or is it better to have any stuff settle and be vacuumed out later?

My sump is not compartmentalized. I have a 20g long with a return pump, an in sump skimmer and a heater. Any detritus that gets thru my filter sock and dosen't get into the skimmer will settle. I vac it out, but would a power head in there work?
 

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Discussion Starter #15
i would tend to think that most of the flow in nature is pretty laminar. back and forth, back and forth with the tides going in and out.

i do also think that once the water column hits the reef the flow will then become much more chaotic as the water pushes its way around/through the reef.

are we all in agreement that the random/chaotic flow is preferred in order to get detritus up and moving so as to get it to an easier place to collect it?

G~
 

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Perfeshunal Hikk
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As long as that "random chaotic" flow is directed to the overflow, sure. If it isn't organized enough to direct to the overflows - eventually - then its just pumping poo around in circles :)
 

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Discussion Starter #18
some would also argue that corals do not need food. the various symbionts would produce the food the coral needs.

though that would be another weeks topic.

either way even if the corals did "eat" the food, they would also be producing waste, which i am sure another coral would not eat, at some point nobody wants to eat the wastes except for the bacteria, and this is what we want to get out of the system. if we put food into the tank than we need to remove just as much waste. our systems are not some magic perpetual life machine. where all poo is the perfect food for somebody else in the system and we never had to feed the system. i wish it was like that, it would make keeping these tank a whole lot easier.

G~
 

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Perfeshunal Hikk
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not so sure this is necessarily a bad thing, depending on the coral stocking level of the tank. many will argue that poo = coral food.
Its a bad thing. No matter how you look at it, its a bad thing not to get the poo out. As Geoff said, eventually the poo that got eaten becomes poo that is not wanted to be eaten and you have to remove it from the system. If you do not have a way to get the poo to the sump, then a sump is pretty much a waste of time and you are wasting flow. There HAS to be an order to the flow in the tank, even if its minute order but it must be there or you are fighting yourself.
 

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but isn't the more important thing to keep the poo in suspension?

i'm not disagreeing that it's important to get waste to the sump...just playing devil's advocate.
 
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