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So, you want to start a Reef Tank ? Water Movement [Archive] - Saltwater Aquariums - Reef Tanks Online Discussion

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reeflounge_admin
11-20-2002, 10:19 AM
So, you want to start a Reef Tank ?

Water Movement

Incorporated into every reef tank should be two basic types of water circulation; Filter circulation and Internal circulation. Filter circulation is water that moves from the tank to the filter system and back to the tank. Internal circulation is the water that moves within the tank itself. There are many methods and theories for accomplishing both. Personally I believe lack of good Internal Circulation is one of the main reasons for algae problems.

Think about it, most reef tanks have an overflow system at the surface of the tank, if debris (eg; food, fecal matter and mulm) are not swept up from the bottom of the tank, or from behind the rocks by currents, then they never exit the tank, via the overflow, and are not removed by the filter system.

At its best, Internal circulation should consist of Surge ( back and forth movement), Turbulence (random swirling movement) and Laminar flow (movement in one direction) [ see Delbeek and Sprung, The Reef Aquarium, Vol 1, page 164 ]. Available are an array of devices to accomplish some of these types of movement.

Wave makers, usually an electronic switching device that turns on and off alternating pumps / powerheads, will generate Laminar flow and some Turbulence. Unfortunately pumps / powerheads were not intended to be turned on and off, and generally the shortest time duration / cycle is two minutes.

Oscillators, there are a few manufactures who produce units that either move your powerhead back and forth 90 degree's, or units with motorized water discharges that move back and forth 90 degree's. These do create "chaotic" Turbulence.

Dump Buckets, an offset bucket that fills and then tips to dump its water, then rights itself to refill. These units create Surge and Turbulence. I don't believe there are any commercial units marketed yet (review either Walter Adeys Dynamic Aquaria or there was an article in MFM a few years back ( Stanley Brown ) on how to make a Dump Bucket out of a paint roller pan.

THE ABOVE MENTIONED UNITS ALL HAVE MOVING PARTS, AND MURPHYS LAW SAYS... < G >

Carlson Surge Device, (see SeaScope, Summer 1996 or CLICK HERE (http://www.aquarium-design.com/reef/csm.html) ), is an elevated tank that when filled will allow a rapid siphon to be created out of the tank and introduced into the reef tank. Once the elevated tank drains, the siphon is broken and the tank refills to create another rapid siphon. This will create Surge and Turbulence.

THE LATER TWO UNITS WILL CREATE MORE SPLASHING OF WATER AND REQUIRE A TANK / OVERFLOW / SUMP THAT CAN HANDLE A FLUCTUATION IN ITS WATER LEVEL.

All the units mentioned above will help suspend debris and particles into the main water column, which eventually will be carried out the overflow and into the filter system. With less debri remaining in the tank, there will become a much lesser chance that undesirable algae's will get a foot hold. Additionally, the corals in the tank will also benefit from the greater water movement, as they will be able to expel waste products and more food will be brought to them. Keep in mind that not all corals will appreciate the greater water flow, these corals can be moved into quieter areas of the aquarium. But after some adjustment, most corals and polyps will expand further, or open larger.

Humu
02-13-2004, 03:43 AM
Is there any rule of thumb regarding the strength of water circulation to have in a reef tank? I've got a 50G and was considering putting in one oscillating power head to increase circulation, but I don't want to get anything "too powerful" (don't like the vortex look in my tank), plus I want to minimize the appearance of the powerhead. In addition, should I go with one oscilatting power head, or two smaller ones instead? Lastly, any recommendations for size and make given my above concerns? Thanks in advance.

Nautica-db
02-17-2004, 11:24 PM
Im new to this stuff. But every where I read its all about the motion an I have seen some setups an was wonder if they would do any good if any?

Drawing (http://68.13.194.14:8080/closedloop.jpg)

Sandworm
02-18-2004, 03:24 AM
The GENERAL rule of thumb for a reef tank on water movement would be between 10x and 20x the total tank size.. For example, if your tank is a 55, you'll want between 550GPH and 1100PGH in water movement. This can be acclomplished with generally 2 - 4 powerheads or whichever method you choose.. The reason you would not want to do all of it with one head would be for better motion within the water.. If you've got 1 head at one end of the tank, this would leave the other end of your tank with almost no decent flow..

Chance
03-27-2004, 03:22 AM
I have read six nice books and 1 said 10x tank volume. The others never gave a specific number. From my experience though 20x-30x seems to be more like it. My Sps and Zoo tank runs at just a tad over 30x tank volume. I also frag acropora in the same tank. However 30x might be just a little much for some if not a lot of soft corals 24 hours 7days a week.

In general (for a reef tank,nano,fish only,fowlr etc) 20x seems to be "The sweet spot" you could say. Or at least a good starting point.

Remember all this 10x 20x 30x is still nothing compared to the the flow of an average reef!!

IT_EXISTS
07-26-2004, 05:24 PM
one word of caution on getting a moving powerhead is that they are a huge pain. i had one in my 54 corner bow reef tank and my 125 cichlid tank. they constantly get stuck or gunked up with debris and are just a huge hassle. the rule is ten times and just place variable power heads in behind live rock and around tank. just conceal them to keep "eyesores" out of the way

nyfireman3097
09-18-2004, 04:43 PM
Hey does having 1950 GPH in a 55 to much i have also have it on a timers so 2 go on 2 off then 20 seconds later 2 go off then 2 go on
Nick

Spy
11-21-2004, 11:49 AM
According to the 10x - 20x rule of thumb should be ok, but on-off-on puts a strain on your powerhead. It's like turning your computer on-off-on, it's probably going to have a problem sooner rather than later. Just a heads up. However, I have done that and had a very healthy tank and just had to replace one after 1 year. The key question is how is your tank doing so far using this technique?

nyfireman3097
11-21-2004, 05:04 PM
everything is gopin good but even before i added the new powerheads im gettin 2 tunze 6100's w/ controller only gonna use one though on low till i get my 125 up and going
Nick