Closed Loop Systems: Pros&Cons

mrbee2828 · Dec 30, 2013

So our addition is just about wrapped up and I am in the research phase for my large build this year. I have been reading all I can about closed loop systems because in my mind I have been leaning that way for the last year in my head. But I'm still not sure and my biggest hang up is peace of mind. I'm very concerned about a potential leak on a bottom drilled bulkhead or the bottom cracking due to having 5 holes in it. I need some perspective from people who have them, maintain them or had them.

I'm looking to do a 7' tank, most likely a 265g Marineland. The tank isn't reef ready and the next best thing to custom setup. It will save me a ton of money. The tank will be placed in the center of the house along a wall in the dining room. You will see the left side centered when you walk in the front door. So the thing is, I HATE SEEING EQUIPMENT. Even loc-line drives me nuts. I want a large back, centered return. I don't want to come home and see a giant MP40 centered on a panel with coral behind it.

I have been thinking about a 4 return closed loop with an oceans motions and several Vortechs along the back. I could also put a vortech on the far right side opposite the entrance. Obviously I'm not going to get good turbulence from opposite facing powerheads but I would assume I would get some decent current from a 4+ vortech setup with a master/slave program on a 2' deep tank. So forget about money right now. This is a long term build in my house that I don't want to redo within the next 5+ years whatsoever. Could 4 or 5 rear placed vortechs be enough to skip the closed loop stress... possibly doing one on the right side only?

My concerns are mostly:

As mentioned, several holes in a large sheet of glass supporting 265g of water.
A bottom sch80 bulkhead failing in some fashion and having a major flood or just in general, repairing it with a total nightmare drain.

Many people will argue space, plumbing complexity, power consumption, cost and maintenance on a Dart etc. For perspective, I will buy an extra Dart to swap out the pump if needed so I have the time to replace parts. I'm not concerned with plumbing complexity and I'm going 7' for space under the tank. So what say you? I've seen a non-drilled closed loop that pulled and returned over the back. I can do acrylic work. What are the thoughts on building a wider overflow with a false chamber to the side? The drain/pull and 4 returns could be hidden inside and look like a larger overflow. I could build the drain/pull pipe screen into the lower portion of this chamber even so as to not pull from crashing water and grab potential air bubbles. Thoughts? What about the addition of a single wave maker in the back right with the vortechs and no closed loop?

DaveMorris · Dec 30, 2013

I am the same way…I hate seeing powerbeads in a tank. I had a closed loop running on my 300g tank and I loved it. I was using a large Sequence pump and an OM 4way. Have you considered drilling the holes in the back side of the tank instead of the bottom? That is how I did mine and the rock work hid the intake and 4 outputs. Nobody could see any of it.

adhd_nerd · Dec 30, 2013

With the advent of the DC 'return' pumps. I think doing a close loop with multiple DC pumps for each different loop to alternate flow is a feasible idea. I think it will be more trouble free with less pressure loss than using diverting valves. If RLSS would release the APEX controllable controller for their pumps you could come up with some pretty nice controllable close loop systems. In the mean time all you can do is turn them on/off but there is a slow ramp time; which may or may not be a problem.

...just and idea I had when building my frag tank.

stunreefer · Dec 30, 2013

Personally would go with what's in your drawing, four VT's along the back and one on far side. Maybe go with a MP60 to fire down the length of the tank. I've installed a MP60 on an eight foot tank and it provided flow at the far end. You would be able to get insane current once you tweaked the settings even while installed on back.

Holes in the bottom are a surefire way for absolute disaster in the rare chance a bulkhead fails... eliminating possible failures is crucial IMO, particularly on an aquarium of this size. If you do end up running CL I would go with Dave's recommendation of placing them on back wall. Again in the off chance bulkheads fail you won't drain your entire tank, saving animal lives and possibly floor. Up and over the back CL's are unsightly most of the time with [necessary] large strainers hanging in from the top.

TUSI · Dec 30, 2013

Mine is a closed loop but my bottom is made from a thick PVC with the bulkheads recessed. Tank is 5 yrs old and have no problem. Although I still ended up do power heads as the tank matured with SPS needed more flow. I also use a wave maker from ocean motion attached to my dart reflow pump

DaveMorris · Dec 30, 2013

adhd_nerd said:
With the advent of the DC 'return' pumps. I think doing a close loop with multiple DC pumps for each different loop to alternate flow is a feasible idea. I think it will be more trouble free with less pressure loss than using diverting valves.

The DC pumps will definitely be much more efficient from a power standpoint. Diverter valves such as the OM 4way do not cause any pressure loss at all. They always have at least two outputs being fed at a time as it rotates. Also, as a side note, you don't experience any head loss in a closed loop system since everything is submerged. All that being said, the Vortech plan would work well, but it would be way more expensive for an initial startup cost. Four MP40s would be almost $2k right there, not to mention the cost of an MP60 at $750 or so. Choices abound…..

mrbee2828 · Dec 31, 2013

All good stuff, thanks. I'm not so concerned about initial setup or cost right now. I have a 125g to play with and I have spent a year on the addition and just upgraded our panel with new breakers for the tank. I'm in no rush. They aren't needed to cycle anything right now and I can look out for used equipment too. The closer I get to buying the tank the more I am leaning toward not doing a CL.

tyeight · Dec 31, 2013

Try this as an option

tyeight · Dec 31, 2013

You would do both, closed and sump with all being managed from your coast to coast overflow built on your tank. But I would still use the MP60's on the side. This was an early drawing I did for a Aqu and later changed the position of the returns along the back wall. Two for the closed loop and two for the sump return utilizing spa jets with eyelets to be pointed in any direction you like. You can add the pumps you want on the different systems.

Fin · Dec 31, 2013

I don't like looking at equipment in the tank either. This is how I set up my closed loop on my 140 about 7 years ago. I did not drill any holes, except the drain to feed the Dart. The drain was drilled in the center back panel and it is hidden by the aquascape. I used an OM 4way and plumbed from the top. I ran two 1" returns along the left & right edges of the top of the tank, to the upper front corners. These were finished off with two OM Omni-Flex nozzles. For the other two returns, I used black PVC pipe and fittings and ran from the 4 Way, down the back glass (aginst a black background and alongside the two overflows. Then underneath the sand bed to the two lower front corners. I covered the two 45Â° fittings with small rubble rock and brought the level of the sand up a bit so it just looks like two clumps of rock sitting on the sand. Here are a couple of pics.