Water motion in tank.

[Troy F]

Shane, I was thinking about what you said about "very little tidal action in the tropics" and would like that clarified if possible. I've not been anywhere tropical myself but do have an understanding about the tidal dynamics and it would seem to me that location would dictate how high the tide would be. I would guess that a lagoonal reef may even get more water motion from tidal action. Did you dive a forereef? I'm a little envious. There is a guy on www.thereeftank.com that just got back from the Indo-Pacific, hopefully he's going to send me a copy of his dive video.

[DJ88]

Shane,

can you clarify the tidal action for me as well. I know that when I was in Australia and anywhere else there is still tides. The hieght of the tidal action depends on several factors but it is there. You won't feel it unless you are in an area where that flow is restricted. Or where the shape of the land dictates and even higher tidal action than normal. ie. Fundy and the St Lawrence. In open water you probably won't feel it persay. The wave action will be what you feel. It is so much stronger than a tidal action. Thus would cancel the feeling or perception of the tidal movement out. Or if the tide was moving in the same direction would add to the wave action. Same ideas as any wave interferance patterns. [img]images/smiles/icon_smile.gif[/img]

To me a device creating tidal action is a good idea. But in our hobby I dont know how realistic or feasable it is. Our powerheads or sea swirls will counteract any slow tidal motion we do create moving from one side to another.

That is from what I have learned about tidal actions tho. And some experience from bobbing on the open ocean.. [img]images/smiles/icon_wink.gif[/img]

[ 21 November 2001: Message edited by: DJ88 ]

[StirCrazy]

but Darren thats the idea.. if I make a tidal system then i don't need power heads in the tank and the tiday will be controled by one pump. (thats why I am going to give making this valve a try at work) it doesent seam hard at all to do. And if I make a rack for my live rock I could maby have a small power head pumping into that and have a slight curent pushing out from under the rocks. I was going to start making it tomorrow but I am having knee surgery on friday so I will put it off for a couple weeks.
about the tropical tides.. yes there are tides about 12 foot tide in Hawaii (been there over 20 times) and in Hanuma *sp bay there is a alternating curent that when you are diving moves you about 10 to 15 feet in one direction and then back again.. and the small reef that is 4 to 5 feet out of the water at low tide is about 4 or 5 feet under water at high tide.
it wasn't the hight of the tide I wanted to replacate it was the predomanant direction of flow during the tides..

Steve

[Silverfish]

Hey Steve, what type of reef are you setting up? SPS, softies, mixed?

[StirCrazy]

well what I have decided so far.. I Live rock tank [img]images/smiles/icon_biggrin.gif[/img] seriously.. it will be a while befor I can do sps I figure I will start off with easy stuff till I get the tank going how I want it ..I might put a fish in there : ) I think the muchrooms and pulsing xena are real nice as well as other softies I have been seeing laitly sooo..

Steve
P.S Bruce, you have to get a web site going so I can see your tank [img]images/smiles/icon_smile.gif[/img]

[ 21 November 2001: Message edited by: StirCrazy ]

[Silverfish]

Sorry man, I can type(sort of), point and click, and that's about it. I'm computer illiterate, you'll have to see it in the flesh [img]images/smiles/icon_biggrin.gif[/img] ,,
unless Adam posts some pics for me.. he took some today [img]images/smiles/icon_cool.gif[/img]

[StirCrazy]

haha no problem.. I have a digital camera also if you even need some pic taken and can't get ahold of Adam

I am having knee surgery on friday so I won't take ya up on that right away but soon hehe

Steve

[Silverfish]

Cool! [img]images/smiles/icon_biggrin.gif[/img]

[DJ88]

Hey steve.. there are devices out there for doing surges.. Is that what you are looking for?

If you are trying to recreate the flow on a reef keep this in mind. You would have to have a flow of 48,000 gallons per hour in a 100 gallon tank. Something we can't attain in a tank.. You are talking about massive pumps there. We can get 2400 GPH pumps. but a problem with having that blasting out of a nozzle in your tank is that it isn't good for your corals to be hit with such force. I have had a coral's tissue recede when a maxijet fell and blasted it for too long. It took a fair amount of time for it to recover. Most won't.

Tides aren't really water movement like most people think.. It is the ocean rising and falling.. That is it.. it is the waves and currents that you feel when diving and what gives the corals the nutrients they need. To me, when you say tidal action you are talking about raising and lowering the water level in your tank to mimic the action you see on shore. If you want to have water flow you are talking about currents and wave action created by the winds(which we try to create with powerheads and pumps), semantics I know.. But those are what tides and currents are. Tidal surges you see in a harbour or on the beach are caused by the water moving up along a shoreline or a channel. When we were out at sea we never saw the tides moving and changing. We didn't have a reference point. On a reef the rising and falling of the tides isn't perceptible. But currents created by wave and wind action are.

One of the reasons for having the wave action and circulation in the tank is for aiding in the removal of wastes to the sump and then the skimmer. Without this higher flow it(wastes) will deposit itself on the rocks and break down in your tank. Which we really don't want. Too many wastes breaking down can lead to algae, cyano and can cause different problems with corals if it builds up on the corals and isn't removed. RTN is one of these, receeding of coral tissue is another. No growth at all is another possibility

The higher flow and random flow helps bring nutrients to the corals. Phyto, minerals etc. Calcium. By lowering this flow you may not replenish the needed or desired nutrients..

IMO, I find the best growth appears on corals in a tank with water flow from a sea swirl. Cycling power heads on and off is another cheaper option. Closed loops sytems area n added bonus and I am concidering it with my 120 when it is built. Those are the options I will chose to use.

If you can stand the noise and the equipment go for a surge device. They do a great job of mimicing the wave action you feel on a reef. Tho they can get blocked up, fail and may overflow or worse.. A new design out there but still not for sale as far as I know is the Wave 2K. Great idea but many moving parts. more parts means better chance of failure.. And with a DSB you will get buildup of detrius and sand in the mechanism. The mechanisms inside that thing for the most part are nylon.. They will wear out fast with sand or crap rubbing in the threads.

I am gathering you want a constant flow in one direction for a specific period of time. then reverses itself. I think the best description of what you want to build is the closed loop circulation system I mentioned. One that alternates. That alone is a good system but to me adding in the random actions the powerheads or other devices add a bit more to the picture. To have that flow you fel in the ocean you would need to have the whole side of your tank as one huge outlet for a pump. Otherwise you will only get the flow you desire for the first few inches out of the outlet.. Then it is sent in all directions. Even then if you didn't have the same huge opening on the other side you woudl not get an even flow. You will get it coming into the tank from one 2 inch opening(assuming 2") and then exiting out another similar opening on the other side.. With that you won't get the flow you desire throughout the tank. For the most part only between the two outlets/intakes. If you have only that you will end up with areas where there is no circulation or turnover of the water. Dead ares in effect.

We are doing the best we can to re-create something we can't possibly provide. that massive water flow you feel on the reef.

IMHO...

[ 21 November 2001: Message edited by: DJ88 ]

[reefburnaby]

Steve,

Low RPM motor ... how about one of those BBQ rotsiere motors. Or how about a stepper motor [img]images/smiles/icon_smile.gif[/img]

Another alternative for water circulation is using one of those plastic water sprinklers ... the one that was three heads and they turn round and round. Don't know how well they work...but some reefers are using it.

- Victor.