Closed Loop

blcard · #1 12/30/2007, 10:50 AM

I've seen many with the inlet coming from the back of the tank and returns going somewhere else.

My question is whether I can you an extra hole in the bottom of my overflow as the feed and the return over the top??

Thanks

Reefbox · #2 12/30/2007, 10:57 AM

You will get cavitation on the pump using the overflow.

blcard · #3 12/30/2007, 07:05 PM

Ok had to look up the word, but hey I learned something.

If the overflow has dorso pipes which keep about 30" of water wouldn't this prevent the cavitation??

rigleautomotive · #4 12/30/2007, 07:14 PM

the problem would be with the over flow not being able to keep up if you use a decent size pump for the cl

KMP · #5 12/30/2007, 07:19 PM

Quote:

Ok had to look up the word, but hey I learned something.

Me too

das75 · #6 12/30/2007, 09:09 PM

Just wondering why it wouldn't work?

Realize not a true CL because drain and returns at differant static head but if a overflow can reach an equilibrium (constant height in OF compartment due size of drain and return pump) then if adding the CL pump pulling from the OF compartment why wouldn't the extra flow over the weir to supply the CL pump cause things to eventually balance out.

OceansWonders · #7 12/30/2007, 09:21 PM

It works just fine I ran a all-glass 90 gallon with the megafow overflow for 2 years that way. had a quiet one 4000 as the closed loop pump. Also had another queitone 4000 as the return in the sump. Had the 1" intake for the closed loop inside the overflow about half way down - lower than the durso drain intake with the returns near each end of the tank on the back wall never had any issues with the overflow not keeping up. It actually skimmed the surface better this way because of the increased flow through the overflow.

It would not be wise to try to add another hole in the bottom of the tank unless you know for sure that it is NOT temperd. The backs of tanks generally are not temperd.

blcard · #8 12/30/2007, 09:26 PM

Ok if using the bottom of the overflow won't work, what's the best way to add a CL to an existing setup.

At 170 gallons its not real easy to drain and move!

OceansWonders · #9 12/30/2007, 09:31 PM

Quote:

Originally posted by blcard
Ok if using the bottom of the overflow won't work, what's the best way to add a CL to an existing setup.

At 170 gallons its not real easy to drain and move!

If you can get at the back of the tank you could just drain the overflow and then drill inside it. Athough I do not know what kind of tank you have or how big the overflow is. IMO it still would be risky drilling a full tank as there is a lot of pressure on the glass panels I would recomend draining. Better to be safe than sorry

blcard · #10 12/30/2007, 09:37 PM

Agreed, really wouldn't want 170 gallons in my living room.

Would draining the tank maybe half way and putting the hole there be ok.

Where should the drain and returns be located on a CL?

Is it just as good to add a couple Koralia 4's?

It's 1" acrylic.

Siffy · #11 12/30/2007, 09:43 PM

There's no need to drill just to add a closed loop. Just run 2 90's over the tank wall. The only issue you'll have is priming the pump before the first time it's run. Easily done by adding a valve high in the plumbing to pour water in or pushing a piece of airline into the plumbing and drawing the air out.

OceansWonders · #12 12/30/2007, 09:53 PM

Quote:

Originally posted by Siffy
There's no need to drill just to add a closed loop. Just run 2 90's over the tank wall. The only issue you'll have is priming the pump before the first time it's run. Easily done by adding a valve high in the plumbing to pour water in or pushing a piece of airline into the plumbing and drawing the air out.

Or you could do the above.

If it's acrylic you can drill the bottom ( I was assuming that it was glass) I would still recommend draining the tank though. The returns you would want as high in the tank as you can as if the power goes out it can back siphon into the overflow if they are below it.

OceansWonders · #13 12/30/2007, 09:55 PM

Quote:

Originally posted by blcard
Agreed, really wouldn't want 170 gallons in my living room.

Would draining the tank maybe half way and putting the hole there be ok.

Where should the drain and returns be located on a CL?

Is it just as good to add a couple Koralia 4's?

It's 1" acrylic.

You could add the koralia's but the idea behind a closed loop is so that you do not have to have a bunch of ugly pumps hanging inside the tank.

scaast · #14 12/30/2007, 10:04 PM

Here is a pic of a my old non-drilled closed loop as described above...worked like a champ.

wizsmaster · #15 12/30/2007, 10:22 PM

Nice looking scaast!

blcard · #16 12/30/2007, 10:50 PM

OK now I'm confused.

The bottom of my overflow has an extra 1" bulkhead. If I connect it to a pump with a return over the top, then the only real concern I see is that the water can't pass through the teeth of my overflow quick enough to keep up with the pump.

Is that right?

Is there anyway to calculate the flow through the teeth? There is about 12" total. The return system is about 800-1000 gph. Was looking to add another 1000 gph.

OceansWonders · #17 12/30/2007, 11:00 PM

Is the 1" bulkhead used now for anything?? Or is it capped off?

blcard · #18 12/30/2007, 11:14 PM

It's capped.

I'm using a 1" and 1/2" currently going to the sump.

fishdave739 · #19 12/30/2007, 11:19 PM

Not only flow through the teeth as a problem, the nature of these tall overflows creates a lot of bubbles, which would get sucked into the intake of your CL. This would create a TON of microbubbles in your display. A hang over the back system would porbably be the way to go!

OceansWonders · #20 12/30/2007, 11:22 PM

So you have 3 bulkheads in your overflow correct.
If it capped you could just use that as your intake for the closed loop.
As far as figuring how much your overflow can handle I'm not sure you can always put a valve on the closed loop and dial it in to what your overflow can handle.

You will still need to figure out what you want to do for the returns.

OceansWonders · #21 12/30/2007, 11:26 PM

Quote:

Originally posted by fishdave739
Not only flow through the teeth as a problem, the nature of these tall overflows creates a lot of bubbles, which would get sucked into the intake of your CL. This would create a TON of microbubbles in your display. A hang over the back system would porbably be the way to go!

The durso intake should be high enough so that the water does not cascade over the overflow which would be awfully loud as well. The water level in the overflow should be no lower than a 1/2" or so below the main tank.

blcard · #22 12/31/2007, 07:36 AM

I'll give it a shot then, as soon as I can talk the wife into more stuff

OceansWonders · #23 12/31/2007, 12:29 PM

Quote:

Originally posted by blcard
I'll give it a shot then, as soon as I can talk the wife into more stuff

Yes THAT will be the challenge

das75 · #24 12/31/2007, 12:42 PM

Fishdave has a good point, CL pulling from the overflow there's a chance of bubbles.

Look on OM site here, lots of pictures of CL to get an idea of layouts