OTB Closed Loop Plans

[treesprite]

I am looking for helpful feedback, tips, and suggestions for the over-the-back closed loop I am planning for a 50g 36x18 Oceanic mixed reef tank. The tank only has one hole in it, and I decided to not drill more of them just to make things easier, so I'm going over the back.

I will be using a 3/4" Sea Swirl, and a 3/4" SCWD. I was planning on putting the sump return through the Sea Swirl. The SCWD would be on the CL.

I already made my CL intake, which is a piece of 1"pipe with a bunch of holes drilled into it. It worked fine testing it with a random 800gph pump through a 1/2" pipe test manifold (the pump only has a 1/2" output).

Since the Sea Swirl will do a lot for the update water movement in a tank with this 36x18 footprint, I am focusing mainly on flow from the bottom up. I will hide the bottom manifold under the sand.

Things to address:

- Design of manifold. Should I use two completely separate ones, given use of the SCWD? (Feel free to post examples/pictures)

- I was originally only going to do a bottom manifold, but how much of an important difference would it make to put at least an output opposite of the Sea Swirl sump return? If I need an upper outputs), how would I figure that into manifold desgn?

- What size of a pump should I use, giving consideration to the use of a SCWD and the possible manifold designs?

- Any suggestions for a pump that will fit into a small budget?

- Any helful info/tips on setting up and using the SCWD, since this will be my first use of one?

- Anything else I may not have considered yet?

Thanks in advance for your help!

 

[mcgyvr]

huh? I might be missing something or you are
You are putting the pump in the display tank right?
Thats the only way it will work if you don't drill more holes.. These pumps are not capable of "pulling" water up and over and should be gravity fed liquid..
Or are you confused on what a closed loop is?

How about sketching a diagram?

 

[EMeyer]

No, with respect, the OP is right. You can do exactly as he describes, I just set up something like that on my tank. Of course you have to prime the pump initially but a standard return pump has no problem pulling water over the back in a HOB configuration.

I have my pump level with the tank, directly behind the tank. Both the intake and the outflows go over the back and are hidden by the hood. So the only visible parts are the ends of intake and outflow pipes.

Advice to OP -- go with the biggest pipe/hose diameter you can get away with, sucks to put in all the work only to have flow limited by diameter. If I redo mine I'll go all 1" until the final fitting on the outflow, currently I'm mostly 3/4 and its limiting flow.

 

[EMeyer]

Oh, and consider a 1" SCWD instead of a 3/4. The item will need servicing, and you cant service a 3/4. Its a sealed unit. While the 1" screws open.

 

[slief]

I think adding a closed loop in such a small system and going over the back like that is kind of silly. You could accomplish the same effect with even better flow by using one or two wave maker type power heads. If it were me, I’d get a pair of Tunze 6095’s and call it day. It will be simple, provide better flow, less complexity and arguably better reliability.

 

[mcgyvr]

I should have been clearer....my fault.. These pump are not self priming and I personally would not use a non-self priming pump in an application that "may" require priming..

 

[EMeyer]

Once theyre primed once they never need priming again unless they leak. Gravity will keep them primed forever after that, barring leaks. But its definitely a non standard arrangement.

slief -- like many things in reef keeping its a subjective matter of taste. But you know how we all react when we see a tank with a heater in the display tank? Thats exactly how I react when I see powerheads in display tanks. I think they are horrible looking and refuse to have any in my tank. Pipe ends dont bother me but I think powerheads are hideous to look at.

Couldnt be happier with my new OTB closed loop, I've doubled the flow in my tank and still have zero visible pumps

 

[treesprite]

I got the idea from Meelev's website. He set up an OTB CL on a 29g tank, using a squid and a mag pump.

FMeyer, what size tank do you have it in? What pump/pump size are you using?

I didn't know that about SCWDs. I wonder is Marine Depot will take back the 3/4" one so I can exchange it.

The reason I won't drill more holes, is that this tank is the result of me being too stressed out when I was trying to set up my 120. I stuck the 120 in storage room. I almost shut down completely; gave away my fish, took almost all of my liverock and crammed it in a tank with a powerheads and unintentionally let all the stars and stuff die off (too bad the black encrusting sponge did not). Then my friend offered a good deal on this 50g which has Starfire front glass and came with a stand. I agreed to take it easy on myself if I got this tank instead of shutting down, so no drilling (I have drilled lots of tanks, so experience with drilling is not the issue at all).). I won't be able to have my favorite fish in this little tank though (yellow zebramosa tang).

 

[treesprite]

FYI, I'm a she not a he.

 

[EMeyer]

Sorry, I generally assume everyone on the internet is a dude until proven otherwise Comes from a long time of hanging out on video game message boards I suppose.

I have a 55 gallon and am using a Jebao dct 4000 for the closed loop, and an MD 9 for the return.

 

[treesprite]

I've decided to stick with the 3/4" SCWD. I would have to wait a bunch of extra time sending back the 3/4 and waiting for the 1".

So, I'm using 3/4" PVC for the manifold. I am wondering, will using 1/2" nozzles on the back outputs, allow more flow to get to the front outputs which will old have 3/4" nozzles (3/4" 45*s)?

 

[ca1ore]

That would reduce overall flow but, yes, you'd see more out of the 3/4" outlets.

 

[treesprite]

I'm not wanting to have an in-tank DSB and risk my tank life just to hide the manifold, so I did some coating with silicone and sand in case the loose tank sand gets moved around too much.









This is a picture of the intake pipe:



I'm sticking with the 3/4" SCWD, so I used 3/4" PVC for the two pipes being fed via the SCWD. The manifold sections that go around the ends to the front outputs, are 3/4" and those outputs are 3/4". The section in the back between the two feed pipes, is only 1/2" for the back outputs, so that the flow from the front outputs isn't weaker than the back ones. I want to be able to point those back ones upward more behind the rockwork, so I painted them black to blend in with a black painted tank back. The section of pipe between the two front outputs I made only 1/2". because I wanted some restriction between them so that using a SCWD wouldn't be pointless.

I don't know about the design with the pipe size changes, restricting overall flow; I think it would just mean more flow going where I want it to go. I guess we will see what happens when it is installed.

I haven't decided on the pump yet.

 

[treesprite]

I was wondering about the DCT 4000 pump, which is controllable and can be used in or out of water. It is not a self priming pump, which should only matter if I take apart the plumbing for cleaning or whatever. Any opinions on this?

 

[treesprite]

I'm started to have second thoughts about the SCWD. Do I really need switching current on a bottom of tank CL? I could put the SCWD on my sump return instead, which might make more sense, even though I will have a Sea Swirl up there. I was not going to have a sump return on the opposite end of the tank because I didn't want to divert flow to the Sea Swirl, but if I use the SCWD up there, I could add a second sump return. Then I would just change the front center section of the CL manifold, where I had reduced the pipe size between the front outputs (I did not glue that one section of pipe, partly because it lets me swivle the outputs, and partly because I wasn't sure about it).

 

[slief]

I'm started to have second thoughts about the SCWD. Do I really need switching current on a bottom of tank CL? I could put the SCWD on my sump return instead, which might make more sense, even though I will have a Sea Swirl up there. I was not going to have a sump return on the opposite end of the tank because I didn't want to divert flow to the Sea Swirl, but if I use the SCWD up there, I could add a second sump return. Then I would just change the front center section of the CL manifold, where I had reduced the pipe size between the front outputs (I did not glue that one section of pipe, partly because it lets me swivle the outputs, and partly because I wasn't sure about it).

Honestly, if you are hell bent on the closed loop, I would ditch the SCWD all together. Use the closed loop to prevent stuff from settling on the bottom of the tank and below the rocks by having a constant flow across the bottom. Use power heads to create flow through the mid levels of the tank to keep detritus and food suspended and use the Seaswirls at the top of the tank water column to create constant surface agitation and send the waste and detritus into the overflow. That is how I do it and I NEVER have detritus on the bottom of my display, If you have a controller for your system and a 0-10v controllable closed loop pump along with 0-10v controllable power heads, you can get creative like I did have slow flow down at night to save power and have some calm, have good flow during light on hours and a flush cycle where your power heads kick up to higher levels along with the closed loop to export anything that has settled.

In my system, I have my closed loop exit through a manifold below my rocks. Essentially it's a 1" PVC pipe that circles my central overflow below the live rock. Every inch or so is a 1/4" hole in that PVC. My 6400 GPH pump feeds that loop pipe through a pair of 1" lines. The water exhausts in a laminar flow patter below the live rock across the entire bottom of my tank. Every couple hours, my Tunze pumps kick into "œflush mode". My tank is 4' x 8' and is setup as a peninsula. I have Tunze 6205's on each side of the 4' end of the tank blasting 8' down the length of the tank. When flush mode kicks on, one side of Tunze's kicks on to full power and the other side shuts off. A minute later the opposite side kicks on while the first side shuts off. At the same time, the closed loop that dumps out under the rocks kicks up to high power to blast stuff off the bottom of the tank while the Tunze's suspend the waste and push it into the upper water column where my 1" SeaSwirls blast the stuff into the overflow. I spend some time testing my flow patterns to come up with something that worked well with my Tunze's for both the flush mode and the other modes i use for flow patters but it works wonders. I never have to vacuum the bottom of my tank or the little sand I have in the center of the display. I will note that I also run filter socks which are a big part of my philosophy with my flow setup and programming when it comes to getting that detritus out of my system. In the end, it works wonders and my closed loop is a key part of this.

 

[treesprite]

Sounds like a great arrangement. I think this tank is too small for all that though.

I ordered a Mag 9.5. Now I think I should dig out my now-burried manifold and change the pipe sizes. I'm going to have to think over my numbers for a while. It will take a while for the pump to get here, so I have some time to do more fiddling and figuring.

 

[treesprite]

Well, I scrapped the project. It just didn't work out right for a bottom manifold. I tested out doing top outputs and it worked fantastic, but that is not what I was trying to do. Oh well. It kept me occupied for a while. Now I can take back half of the PVC parts I bought.

 

[treesprite]

I guess if I just put low outputs and not use a manifold at the bottom of the tanks, or maybe just put a spray bar in the back behind the rocks, using a smaller pump. I just don't like the idea of a powerheads that low in the tank, and want something that low to keep stuff from settling.

 

[BigDave]

I did this same setup on a 30 gallon tank.

I used an OTB to a Mag 7. This then fed the 3/4" SQWD. My output was just two 3/4" 45* pipes one in each back corner of the tank pointing the the opposite corner (kinda an X pattern). This was more than enough to create quite a turbulent flow in the 30 gallon tank. I never had anything settle on the bottom of the tank.

My sump return was another Mag 7 just going to a manifold across the back of the tank.

I think if you did the same with the Mag 9.5 in a 50, you'd see a lot more flow.