Questions about flow
 

Hi everyone. I have a couple of questions and I'm hoping someone with some expierience could help me out.

I am having a 260 gallon tank built. I am going for a natural look, so I don't want to see anything in the tank.(Powerheads, overflows, ect.) The tank will have an external overflow. I am hoping to raise softies and LPS.

I am concerend about the flow on this system. It will have two litle giant pumps providing 750 gph each to the four locline returns coming into the tank from the eurobracing.

Should I have some sort of closed loop system set up on this tank? Or something else to increase the flow? Bigger pumps?

How can I provide better flow, and still keep the equiptment invisible?

Thanks for any help!

Thinking might be a little low even just with soft and LPS.

CL are nice but you do have the noise associated with the pumps though the smaller Reeflos (I'm using a Dart on my CL) are rather quiet. If you are thinking CL even if not using OM products look at their Pix section for layout ideas.

High flow PH might not be that bad though, specially if noise a concern, look at this excellent thread, Nilco16 had started with a CL then moved to PH (starts around post 98), part though again if doing a CL don't go to massive on a CL pump specially if you're planning on having it in the living room (Greenspotterpuffer had similar problem).

I didn't want any ph's in my system, so I designed completely around CLs. I have two CLs, but each one required a big 2" intake...so maybe I traded large strainer intakes for PHs.

There are 4 outlets in the back wall...and 4 outlets on the bottom of the tank. Mostly, they are difficult to notice. In this photo, you can see:
- 1 of 4 back wall outlets on the far left
- there is one floor outlet hidden in the Xenia on the far left
- there is one floor outlet behind the rock, just below the yellow tang
- you can see a floor outlet in the left side cave below a red sponge

From the front, both intakes are hidden...but you can see the reflection of the one on the left.
http://i142.photobucket.com/albums/r...s/100_0006.jpg

Would bigger pumps work, or should I have some inlets at the bottom of the tank?

For a CL you need inlets from the tank below the water line either sides or bottom.

My understanding the 2 Little Giants are feed from your sump, so increasing their size, your pulling more water through your sump. Some concerns there; increased noise from overflows, splashing/bubbling where the water enters sump (some of this can be eliminated if having a Herbie), solving microbubbles back into the display.

The tank is currently being built so its not too late to have some more holes drilled. I want to build it right. It will be much harder to change later.

How about four inlets on the bottom of the tank set up with a 2000 gph pump on a closed loop? Plus the four locline sump returns coming into the tank from the eurobracing.

Would that be better?

why not one hole the size of the pumps intake down low then a couple return holes higher up?

Besides noise, are there any downsides to a closed loop?

Besides noise, there is extra plumbing and higher possibility of leaks.

Alternatively, you can try external waveboxes for flow like this person's tank:

http://i46.photobucket.com/albums/f1...aveboxview.jpg

http://i46.photobucket.com/albums/f1...andwavebox.jpg

It's kinda hard to move the holes once they're drilled and because of this you have to arrange your rockwork around them. You can snake some locline around to rearrange some flow, but then it gets tricky keeping everything hidden (which is the whole point of a closed-loop over powerheads in any event).

Holes cost money to drill and it may make the tank harder to sell in the future as the majority of people looking for a used aquarium just want a glass box.

A big closed-loop pump will use more power than a few well placed powerheads like Tunzes.

Lastly, many people underestimate both the cost and amount of work involved in hooking up a closed-loop especially if you get an oceansmotions-type device. PVC parts can get expensive very quickly especially if you're incorporating various shut-off valves for ease of maintenance.