questions about flow patterns in SPS tank

[rocknut]

I'm hoping someone can help me fine tune my circulation setup in my 65 gallon tank. My primary circulation is thru an oceansmotions 4 way wavemaker (alternating about every 12 seconds) the flow is right around 1000 gph thru 1 inch outlets. I also have two stationary powerheads (one in each corner) and my sump return, which keep a nice indirect flow at all times. My main question is: right now I have each wavemaker return primarily hitting one of my main sps "patches" from about 6 inches away. So each patch gets a very direct flow about 10 seconds out of every 40, the other 30 seconds is a nice indirect flow. How do I know if this is too much? I can switch so that the direct flow is coming from across the tank, traveling about 30 inches instead, but I don't want to go too little either. Any help and/or suggestions would be greatly appreciated. Thanks!

 

[Acro1]

rocknut, I guess the question is how do the corals look? Are they getting descent polyp expansion? Any area's where recession is noted, perhaps some diatom type growth? I personally think your ok. Though I guess it should be noted weither your refer to frags or colonies. Where frags will not disperse the flow as well as colonies. As well colonies will most likely need/prefer a higher flow then frags.I also think by just keeping an eye on things you'll notice any problems if they occur. I have pretty decent flow in my system and don't seem to have any problems. Just keep your eye on things The only real problem with that flow is say if the wave maker locks at one of your concerned positions.

 

[Len]

I've always planned circulation around the concept of mass water displacement with minimal velocity. So in this light, I think shooting the outputs to travel across the entire tank is better then jetting colonies a few inches away. If the acro polyps close up when the outputs blast them, you know it's too much. It's also going to skew their growth pattern. Lots of flow with the least amount of velocity is my motto

 

[rocknut]

Thanks for the advice guys! Thats what I was looking for. I've always found it difficult to really understand exactly what was meant by "moderate" water flow, or "strong", because it can be so subjective. But that makes sense, to move as much water as possible without blasting it. I think that I am getting good polyp expansion, but I keep seeing these pictures of polyps "hanging" out of the corals (they don't even look like stony corals ), so figured I could probably fine tune a bit. I appreciate the suggestions! Rocky

 

[Unarce]

I keep seeing these pictures of polyps "hanging" out of the corals (they don't even look like stony corals ), so figured I could probably fine tune a bit.

They should be, but it can also depend on whether or they feed mostly in the day or night.

 

[Anonymous]

..and light, too.

 

[elpescado]

Ditto on what Len said. Lots of current, low velocity (use flares on power heads).
Laminar flow, not linear.

 

[rocknut]

Do you think that the one inch returns should help some to spread out the flow (as opposed the half inch returns coming from powerheads)? That was my thinking when I setup the closed loop. I think that I will try to adjust the returns so that they are aimed at my coral patches across the tank, that should give the flow even more chance to spread out. That way each coral area should have alternating direct flow from at least two, if not three angles, and indirect flow at all times. I sure appreciate the comments, and suggestions. Thanks, Rocky

 

[Acro1]

Rocky, Yes I think the 1" lines help alot and that is why I think you are fine with the design you described. Len's thoughts are good and I agree with him in those regards. Its just not as easy as it sounds when your dealing with a small stocked tank, and tring to create a high flow system. I think for the most part whats important is the corals get a nice wash with the current but not a pressure wash, like from the smaller nozzeled powerheads.

The corals that you decribe as "polyps "hanging" out of the corals (they don't even look like stony corals) I personally don't believe that is a look one is wanting to create. Other then a few species that are naturally"hairy"

 

[Ralphyhp]

I just want to say to Acro, very nice work!

 

[hillbilly]

That's why I love Tunze pumps so much. They produce gentle current at insane flow rates. High flow without "pressure washing" your corals.

 

[rocknut]

The Tunze's are great, but I don't think I could pull off something like that in a 36 inch tank...Definately makes for more of a challenge.

 

[Acro1]

Ralphyhp,Tanks I mean thanks

 

[hillbilly]

Actually, the Tunze Turbelle electronic 7200/2 with the singlecontroller 7091, called the Model 7210/2, would work quite well with your 36" tank. With the controller you could control the minimum and maximum output as well as have pulse time. You would also have a foodtimer that could switch the pump off with a push of a button and automatic restart after 8-10 minutes, and night mode which reduces the output of the pump at night with the lights off. Try doing that with a closed loop or a bunch of powerheads.

 

[npaden]

I try to shoot for nothing higher than 4 ft/sec velocity. That would be 600 gph through a 1" diameter pipe. At 1,000 gph through a 1" outlet you are up near 7 ft/sec and can damage a coral pretty easily. Of course as the flow progresses into the tank it dispurses and slows down (it stays the same amount of flow - it is just dispursed) so if you wanted to have the output several feet away you could get away with higher velocities at the output.

I get my velocity numbers from a high current reef with a 3 mph current. That translates into a 4 ft/sec current. That is a very strong current if you are a diver and at peak currents like that most corals will close up a bit but will be fine.

Oh well, I got stuff to do but this is a really important thing that most people don't really think through enough IMO.

Have fun.

Nathan