Can you all explain to me what a CLOSED loop is before I order a tank?

[jfolley67]

HI guys, I am going to glass cages this weekend to hopefully order a new tank. I am going to have to have it drilled...probably a 180 with dual overflows...but can someone explain what a closed loop is and how you do it? I know you need more holes drilled for it so want to figure out if it is something I want before I get there. Thanks for your help!!
:D

[fishdoc11]

A closed loop is basically a sytem of PVC piping and a pump that removes water from the tank and returns it creating flow. Do a search. There is a ton of info about them on RC and elsewhere. All different kinds of designs.
Chris

[rcmike]

You don't necessarily have to have holes drilled for a closed loop. I have mine running over the top. You just need a way to fill it up with water before turning the pump on.

[jfolley67]

I figured since I am having the tank drilled anyway, it might be good to have it also drilled to have a closed loop, seems it would be easier maintenance?

[YodaHart]

If you go with the drilled version, make sure you put valves and unions on each pipe near the pump. This will allow easy removal for cleaning and replacement. You won't have to empty your tank to remove the pump.

The basic idea of a closed loop is to have the intake and return(s) of the pump under the tank's water line. The most basic closed loop is a normal powerhead inside of a tank.

[anthony34]

The closed loop is not really a matter of maintenance although if done correctly maintence on the pump that you will use would make life easier to clean usually a shutoff valve on each outlet and one from the pump would do the trick or just one from the pump, it mostly useful if you really not interested in adding powerheads in your tank for water movement some people do not like the look of 2 or more powerheads in their tank so they may go the closed loop option to feed water to a SCWD or Oceans Motions Squirt in many cases it give the tank a much cleaner/natural look. In my case I just got tired of 1 the way they powerheads looked in the tank and 2. The things after a while would fall from the glass and hit my corals.

[jfolley67]

yep, I have 5 powerheads, 4 in each corner and one rotating in mid center back and I am so tired of all the equipment in the tank. Do you recommend drilling for a closed loop? I just want to get it right this time..I want to have this next tank for many years so trying to go slow with its setup.

[anthony34]

It really does not matter, but I guess it would be just a bit cleaner if you were to have a intake drilled, but truly all you need is just a PCV pipe that runs down into the water to pull the water out of the tank either way would work.

below you can see when my intake is it controls 7 different spray area in the tank, mine is under the overflow with a guard on it so that the fish or anything big does not get sucked in it, the person I got the tank from already had this style done, I really like it, but again it really does not matter.

http://i8.photobucket.com/albums/a20/Tonyintn/ClosedLoopIntake.jpg

[fishdoc11]

Here is a good diagram of a small closed loop. I would skip the Squid and use an external pump though.
http://www.melevsreef.com/closedloop.html

[anthony34]

I second skipping the SCWD, takes alot of the water pressue away from the flow forcing you use a larger pump to try to make up the loss. I would use the Oceans Motions Squirt but they are a bit expensive. I also used melevsreef example that Fishdoc11 is showing when I made mine.. pretty easy to make.

[fishdoc11]

Another thing to think about are eductors or penductors. I finally added the ones I bought a couple of months ago to the existing closed loop on my tank today and all I can say is WOW! They at least tripled the flow.
Chris

[boofer]

The SQWD roughly takes 30% of the flow away. But, if you go with the Penductors on your returns side with a SQWD you will get more than enough flow. I got at least a double increase in flow using both of them in my tank. I was estimating around 450GPH before the penductors (SQWD,Mag7) and close to 8-900+ after the penductors were added to my CLS. So actually Im getting more flow than my Mag7 can produce alone with the Penductors/SQWD. The SQWD is a cool/cheap alternative to wavemaking if you take into account for the loss it produces with your pump and/or the addition of penductors....JME, hope it doesnt add to the confusion :D

[SRA4031]

Make sure when you order, you are specific, get it in writing. A reef ready tank with overflows does not mean it has bulkheads or a return drilled in.

[imsqueak]

I'd recommend getting it drilled with a hole big enough for a 1.5" or 2" bulkhead so the suction is not so strong that it sucks your fish to it. Like Chris said, do the searches and see what others have done. With a 180 you might be considering 20x turnover for your CLS - that's 3600gph that you might consider splitting into 2 or 4 returns (holes) and it will created one heck of a suction for the feed. Even on 1.5" strainer you will probably feel the pull 2-3" away. Plan, research, plan, ask, plan and then do it...

[jfolley67]

goodness, wish I understood this all.......ugh!!! I guess I still have alot to learn here with doing the close line idea, but I know that is what I want. Now if I can only figure out how to plumb it! I will figure it out I am sure, it is hard to invision without the hands on but we will figure it out....maybe some of you can give this newbie a helping hand when you have a chance! I am going tomorrow and hope to try and at least pick out the size for sure...whether I get glass or acrylic kind of thing....I am sure I am going to need help here.......but I am excited also about the upgrade. Wish me luck tomorrow....

[fishdoc11]

Here is the how to part of the closed loop. Just keep in mind when reading it you will probably be building yours out of 1" and then restricting it at the outlets for more velocity.

http://www.melevsreef.com/how_to_build.html

Good luck:)

Chris