Closed loop?!

[RJKain-777]

Thinking of adding a closed loop to my tank using the cor20 pump I have laying around. Yes it’d mean I’d be drilling into my brand new tank (it’s not tempered).

tank is 84x31.5x30, 345 gallons.
My plan is to put 4 Mp40 on the overflow wall ( it’s a peninsula ) and 2 gyre fx280 on the far end. I was thinking of Addi the closed loop, with 2 1 inch holes under the outter rock structures, and a 1.25 inch hole for intake under the centre structure? Would this be a good idea?

 

[Kodski]

Closed loops are underrated in my opinion. Especially now that return pumps can also be programed and or come with variable functions. I think it was reef builders who just did a build with a two pump closed loop system. Honestly, one pump for a tank of that size will probably be underwhelming though. If you're going to go through the trouble, I'd do two pumps. Your overall flow will be much better that way too.

 

[mikee002]

I just decided to do one on mine the other day. Very underwhelmed by my new MP10, a closed loop with 2-3 returns will be awesome, and provide much more flexibility.

 

[RJKain-777]

Closed loops are underrated in my opinion. Especially now that return pumps can also be programed and or come with variable functions. I think it was reef builders who just did a build with a two pump closed loop system. Honestly, one pump for a tank of that size will probably be underwhelming though. If you're going to go through the trouble, I'd do two pumps. Your overall flow will be much better that way too.

The closed loop would be a add on to the rest of the flow, just to get movement within the Rock structures. Maybe I’ll get a second cor 20 then

 

[mfinn]

I really like my closed loop on my 233 gallon tank.
It gives alot more options when it comes to flow, and it's hidden.
I don't know what what the suction side of the cor pump is, but make sure the suction side of the closed loop is at least as big.
Plus with 2 return holes you can go with just a tee on each and have water flow 2 directions, or you can add a 4 way tee and a regular tee on top of it and have water flow in 4 directions on each return.
I lost the link, but there is a place that has 1" loc-line and fittings ( maybe someone else knows) so you don't have to restrict the flow ends to 3/4"

 

[jda]

Closed loops are great in larger tanks. There are pumps more suitable to the job, though. 2000 gph non-pressure DC pump is not good for this, IMO. Look at a 6000 GPH AmpMaster, or the like. You want velocity to come out of the pipes, not a trickle... 2000 GPH with no velocity will not do anything in the tank and you want to be able to neck that down to 3/4 if you need to and have it jet out, but you need a powerful pump for this.

If you do this, I would use threaded bulkheads on the in-tank side. This way, you can thread in caps on the water side if you ever have to work on the outside of the CL. You other choice is to drain the tank down below the holes. Don't forget your unions and valves and all of that.

Oceans Motion 4 way is a neat tool to get you some random-ish flow.

 

[RJKain-777]

Closed loops are great in larger tanks. There are pumps more suitable to the job, though. 2000 gph non-pressure DC pump is not good for this, IMO. Look at a 6000 GPH AmpMaster, or the like. You want velocity to come out of the pipes, not a trickle... 2000 GPH with no velocity will not do anything in the tank and you want to be able to neck that down to 3/4 if you need to and have it jet out, but you need a powerful pump for this.

If you do this, I would use threaded bulkheads on the in-tank side. This way, you can thread in caps on the water side if you ever have to work on the outside of the CL. You other choice is to drain the tank down below the holes. Don't forget your unions and valves and all of that.

Oceans Motion 4 way is a neat tool to get you some random-ish flow.

If I were to do this, I’d add valves at every bulk head. This will just be supplemental flow in the rock work, so I think lower flow would be fine in the rock work

 

[ca1ore]

I hate grinding holes in the bottom of my tanks. Leaks are a huge problem and bulkhead failures not uncommon. If you are going to do this, definitely use Sch80 bulkheads. I had a peninsula many year sago, and rather than drill holes, I ran PVC lines under the sand and exited them a bit higher up on the wall proximal end. Only works if you plan to have sand, of course, but mitigates against the most catastrophic failure. Agree that the OM is a nic device, though variable flow pumps have made it less of a differentiator.