What is this closed loop/drilled tank stuff anway...

[Piscevore]

Since I lately tried to sell a advanced reef ready tank, I was suprised by the number of people who really had no idea what I was talking about! As a result, I'm going to post a few pictures of a few things, mostly for your newer folks. (You can still buy my tank too,after, if you want!)

This first photo shows 2 different size hole saws, one that fits a 3/4 bulkhead (1" hole) and one that fits a 1" bulkhead (1.5" hole). When you drill a tank, bulkheads are used to allow you to attach your plumbing. This tank was drilled, but never plumbed, so I bought some 3/4" plugs and threaded them into the bulkheads. That is what you see in the photo. You can see also the nut and gasket for the bulkhead. The bottom image is of a attached bulkhead on the painted black back surface of my 65.

 

[Piscevore]

The bottom of this tank is tempered (as are most large tanks) so I couldn't drill through the bottom. Instead, I drilled the back of the tank for an overflow drain, 3 holes for a closed loop, and a final hole for the return up and over the overflow.

 

[Piscevore]

The way my overflow works: I have a flat long piece of acrylic across the back of the tank at an angle, siliconed in with regularl old GE #1 window and door silicone from Home depot (it is tank safe). The acrylic stops just after the bottom of tank top trim, leaving a good 1/2 inch of room to the tippity top of the tank. When the pump fills the tank, water flows up and over the lip of the overflow, fills it up to the height of the bulkhead, and drains out and down through flexible pvc hose, into my sump. This is a 1" hole.

The water is 1/4" or more higher than the level of the overflow (if that makes any sense), because it goes up and over the plastic. I made sure that when the pumps turned off, the water level of the tank was just at the trim. You can use a very small sump with a system like this because very little water drains when you turn off the pump.(remember, the overflow, if water tight, is within 1/2" of the top of the tank, and the tank is never totally full. When the power shuts off, you are taking less than 1/4" depth from the tank, which is very little volume).

The return I drilled into the adjacent side of the tank, inside of the overflow.I then have a threaded 90 that you can just screw a piece of loc line into. This hides most of your return, and looks kind of cool. My trick with returns is that when the pump is off and the tank is no longer draining, at least some portion of the loc line nozzle is above water. In some cases the nozzleis above the water even when the tank is totally full. This prevents a siphon from developing, and draining your tank beyond what your overflow would normally allow. If you poke your return nozzle 6" down into the tank, and turn off the pump, you are going to drain the tank down until the return nozzle is no longer under water

I like to do as much as possible to prevent bad things from happening to me :0

 

[NateHanson]

Good explanation. I'm moving this to DIY.

 

[denvig]

That "return up and over the overflow." must be a very loud splashing waterfall.

 

[Piscevore]

So what do you do with this tank? Head out, purchase a SCWD and a pump. Hook the pump INTAKE to the center hole, and plumb the output of the pump to the input (bottom) of a scwd. The two "arms" of the scwd get plumbed to the left and right holes. What you now have is alternating current that essentially cleans your rock and prevents detritus from settling in the back corners of your tank. With an ocean motion squirt you can plumb these two holes, plus an additional 2 more, with spray bars etc that would hang down into the tank.

 

[Piscevore]

That "return up and over the overflow." must be a very loud splashing waterfall.

Well, unforunately no, I'm not a big fan of waterfalls or splashing, so I screw in a piece of lock line, and it is completely silent.

 

[NateHanson]

So what do you do with this tank? Head out, purchase a SCWD and a pump.

Ryan, please try to stay clear of a sales pitch. The explanations and illustrations are great though. I'm also happy to put this in the Equipment forum for you if you'd like, then you can say whatever you want.

Nate

 

[denvig]

Got ya That works.

 

[Piscevore]

If you are lucky, and get a tank that doesn't have a tempered bottom, you can do really cool stuff.
I'm super happy with my new center overflow tank.
I have slip bulheads in the bottom of the tank, a custom acrylic overflow box, and a simple stand pipe for my return and durso for my drain. I can just pull either right out for adjustment or cleaning. Its a great spot to grow mangroves too

 

[Piscevore]

Please, feel free to ask any questions about things I didn't mention, or how things are done. There are a dozen tips and tricks I know I am forgetting. Hope this helps explain some.

 

[Piscevore]

Heh, I'm only selling the tank, you have to buy the scwd and pump elsewhere. But regardless, if you want a closed loop, typically you need to purchase some sort of controller. We've had some discussions on home made switching devices using mutually exclusive solenoid valves (when one is off, the other is on) and a T... but SCWD or Squirt/4way are the only commercially available mechanical wave makers I know of? (Everything else is powerheads and controllers)