My tank is what I consider a closed loop, but I must say that a key issue I run into is nutrient export, and keeping the slim off the surface.  The tank is not drilled, so I created my own little contraption to make it work.  I took 2" pvc pipe and made surface skimming device. 

***I removed the image and comments to not cause confusion on the topic.

Whitereef,  I'm kinda confused on your drawing.  That doesn't look like a closed loop to me.  It looks like you have a pump set up to take suction from a surface skimmer.  Is that right?  Is the pump in the tank or outside the tank?  Adding a closed loop to a tank with an existing sump/refugium/skimmer/ect, should not effect niutrient export.  The closed loop is just to add circulation (external from the sump, but without powerheads stuck into the tank).

Bruce, set it up like the one in your link and you shouldn't have any bubbles (as long as you glue all the fittings).  But I would skip the sqwd.

Yes it is a surface skimmer

Pointing the pump/powerhead at the surface of the water doesn't keep the protein in suspension?

Also the 29 gallon tank used to show his closed loop does not have a sump

I think it does, if you look at the picture that shows the back of the tank.  You can see the closed loop, the HOB skimmer (Aqua C Remora?) and the overflow box for his sump.  Regardless, we were talking about Bruce's tank anyway and I know he already has a sump/refugium/skimmer so he shouldn't have any nutrient export issues caused by adding a closed loop, at least in my opinion.

Hello everyone,

I would like to know if there is anything anyone has done that has been unsucessful and if there is anything I should avoid.

IMO there is a golden area for the intake. You want it high enough to prevent a syphon disaster should something in the loop leak. You also want it to be low enough to stay active if the return pump stops. Assuming of course that youre using a return and overflows.

Melev's system is of course the basic idea. Personally, I don't like his intake. It can easily satisfy the above conditions, however I find it to be an obtrusive eye-sore. I used simple 3/4 cone shaped screw in strainers for my intake and I'm quite happy.

Hope that helps,

Chris

Jon - the protein on the surface collects and pointing a power head at it does not break it up sufficiently, so the surface skimmer works to over come that.  But a protein skimmer would also help eleviate the problem.  Also I agree that if you adding something like that to an existing tank the nutrient export should not be a problem.

Bruce - which tank is it going on?

Chris - the system would never have a syphon problem unless the system has a break in it.  I do agree that the intake is an eye-sore and using a strainer would be a better option.

Hello everyone,

the system would never have a syphon problem unless the system has a break in it.

Exactly, things go wrong. I'd rather avoid a disaster than clean one up.

FWIW, a small hole drilled near the water level could prevent a sphyon disaster. However this hole still needs to fall in the "golden area" to prevent problems when the return pump stops and the water level drops.

Hope that helps,

Chris

Bruce,

After Anthony's talk I am giving great consideration to trying a closed system.  I have a rio 2100 that I could use.  I have some sea swirls in the back of the tank but as I am finding out I need more coverage, meaning I need some flow from the front of my tank to the back.  Have you set yours up?  Any problems?  And did you follow the basic design in the site you addressed?

Thanks,

John

Shane,

I was thinking the same thing.  I didn't like the design of the cl bruce, has submitted only because it has too many external pieces, my luck I would have a leak.  So, I was thinking about an internal setup but am not sure how to attach the SQWD to the tubing without metal brackets.  I was thinking cable ties but would like easier access, plastic brackets? 

I'm not much of a DIY'er but wouldn't mind giving a manifold a try.  How does this work? 

John

Bruce,

How many 't's do you have for your 600??  I have a rio 2100 that pumps 600 but I don't think that more than one (i just have a 90) would produce enough flow.  With only one I am looking at nearly perfect (maybe a touch less than desired) flow.  I am planning on replacing the rio (it's the pump I use when doing water changes) anyway so I might buy a larger pump and put it on my cl and add a  't'.

Shane, you were right.  No need for brackets the tubing was snug enough!

The project took me about a half hour...the quickest and easiest tank project ever!!!  So, if anyone else is thinking about doing this, just do it!  It's fast, easy, cheap (except for an adequate powerhead, but we all have extras lying around anyway) and most important, turbulent water flow to the front of your corals!!

John

Bruce,

The jury is still out for me on whether I'm happy with this flow.  It seems to strike the corals fairly well but  I would like to 't' it so that the whole top of the reef is hit.  I thought about this last night...

Does anyone know if by placing an inline 't' actually increases flow?  I'm worried about decreasing the flow but thought I read somewhere that this might eliviate some of the burden (speed up flow)?

I'll probably pick up a few 't's on my way home and try tonight.

John

3/4 inch pvc works great!  When tied up against the plastic crown of the tank it's hardly noticeable.  The thing that I think was great was that the internal pressure of a Rio 2100 isn't great enough to cause a major leak (all my plumping is internal), so I didn't need to seal the pvc!  So I can continually take the system apart and replace with different fittings to see what works best.

John

Thanks for everybody's answers. Still haven't decided if I'm going to go with 3/4 or 1/2 pvc yet

jglover how did you connect the locline to your sqwd?

Just to let everyone know...placing a 't' inline with a rio 2100 (692 gph) doesn't work!  I place one 't' before my 90 and noticed the flow out the 90 barely chanced! but the flow out the 't' was barely noticeable.  To solve this you may need to use a 't' with an endcap to create backpressure to increase flow out of both, but I don't really believe it would work well.

Using smaller pvc will actually decrease your flow and create backpressure on your mag5.  Using larger pvc decreases viscostiy (resistance to flow) so, more water will actually flow and it will be less hard on your pump.  (this isn't hard fact just what I have been told and read).

This project is so easy and cheap that you can get both sizes and try it out.  Someone on the message board may even have extra pvc/ fittings.  I have some 3/4 't's you can have

John

'm trying to figure out if this would work for my closed loop outputs. The left side is a 90 degree tee for surface agitation and general water movement. The right side the tee is for countercurrent (maybe) and the elbow would move water behind the rocks.  The plumbing itself is going to be mag5, SQWD, and 3/4" PVC. The tank is also only 18 gallons. Here is a bad drawing:

Bruce-
So can you tell us about it?  Did it work out for you?  I'm struggling with mine.

Adam

Sorry to revive a dead thread, but I'm about to get parts to put a closed loop together but I'm not completely sure how to do it. How does it look to have diffusers in the front of the tank? Would it look better to only have them coming out on the back and sides?

Pistonfisher, do you happen to have any pics of your system yet?

I built my manifold so it goes all the way around the top of the tank.  Then I have lots of outlets.  Most of them are capped off, and 4 of them have locline.  I have one from each direction, but if I had a bigger tank I think I would make all the outlets on the front of the tank pushing towards the back.

Adam