My Closed-Loop/Spraybar System

Pomacanthus1 · #1 07/12/2004, 09:26 PM

I'm hoping I can get some good criticism on this, as it's my first time working with more than three pieces of PVC and definitely the first time I've done anything relating to a closed-loop circulation system.

Diagrams of my planned system can be found here:
http://pomacanthus2.tripod.com/gener...album/id1.html
http://pomacanthus2.tripod.com/gener...album/id2.html

And yes, I realize the pump is backwards in my diagrams.

A few of the concerns I have with my plans are (1) if the Mag12 will be fine just hanging from the plumbing and (2) if 600gph going through the spraybar and 300gph going through each of the SCWD's outflows, not counting back pressure, is the right amount of flow for my softie and LPS dominated tank. With a Mag12, I'm looking at about 21x tank turnover per hour.

If the Mag12 is too heavy to hang from the plumbing, I suppose I could just strap some metal bands (the ones used to secure tubing to hose barbs) around it and hang it from some hooks or something. However, it seems that maintenance would be easier if it were just hanging freely.

I've practiced a bit with a few pieces of PVC, just to get a feel of how long it takes for the glue to set and the best way to get the pipes as far into the fittings as possible. Also, if anyone has any advice in general about working with PVC or actually putting together a closed-loop system, I'd really appreciate it. Thanks.

laugh · #2 07/13/2004, 01:54 AM

Don't put those metal straps in your water. They will corrode. Make a small stand out of pvc pipe or something to set the pump on.

Bamm Bamm · #3 07/13/2004, 09:04 AM

I would not hang the mag12 from the plumbing they are heavy and you'll probably end up cracking the front cover on themag and causing a leak.

Pomacanthus1 · #4 07/13/2004, 10:46 AM

The Mag12 will not be submerged and there will be no metal straps inside of the tank.

Pomacanthus1 · #5 07/14/2004, 09:52 AM

Another thing I've been wondering about; how big should the holes on my spraybar be? I figure I'll drill them every inch and at a 45 degree angle to the bottom of the tank, but I really have no idea what size to drill the holes.

DonBossung · #6 07/14/2004, 10:00 PM

The SCWD will reduce flow through the two outputs. I think you will be looking at 200-250 on each IMO.

For the holes in your spraybar. Find the area of the spraybar. If 1" pvc then pi*0.5*0.5=0.79 sq in.

Now take a random hole size, lets say 3/16 (0.1875) Find the area of that hole 0.09375*0.09375*pi= 0.0276.

Now divide the area of the spray bar by the area of the hole 0.79/0.0276=28 (give or take). You can have 28 3/16" holes in a 1" diameter spraybar.

What I usually do is drill maybe 2/3 or 3/4 the number of holes and then add more if I think the flow is too strong after testing.

Hope this helps.
Don

mylittleocean · #7 07/14/2004, 10:21 PM

Quote:

Originally posted by DonBossung
The SCWD will reduce flow through the two outputs. I think you will be looking at 200-250 on each IMO.

For the holes in your spraybar. Find the area of the spraybar. If 1" pvc then pi*0.5*0.5=0.79 sq in.

Now take a random hole size, lets say 3/16 (0.1875) Find the area of that hole 0.09375*0.09375*pi= 0.0276.

Now divide the area of the spray bar by the area of the hole 0.79/0.0276=28 (give or take). You can have 28 3/16" holes in a 1" diameter spraybar.

What I usually do is drill maybe 2/3 or 3/4 the number of holes and then add more if I think the flow is too strong after testing.

Hope this helps.
Don

Welcome to RC.

WOW what a great first post.

coralnut99 · #8 07/15/2004, 11:34 AM

Definitely make a stand of some sort to sit the Mag on. I agree about the stress on the front cover. (.5's and up are VERY heavy.

Two scwds will significantly decrease flow. Enough so that a spray bar may end up being a drip bar. I have a M24 feeding 2 scwds on a sump return to a 125 at about 5' . I thought about adding a 3rd scwd, but I just don't see there being enough flow.

I'd do a lot of testing, and see if the flow through the spray bar is in fact too low even with fewer holes than you'd like. The worst that could happen is you have to cap off the PVC to the spray bar, or go to a bigger mag.

DonBossung · #9 07/15/2004, 01:19 PM

mylittleocean: ummm, thanks

coralnut and others are right on track with a stand of somesort. At marine depot (others?) you have to pay overweight shipping on the larger mags. They are hefty.

In addition to my last post, let me say that 1" pipe would be the minimum I would use on the returns. Not sure about the intake as I have always used the mags submerged.

don

coralnut99 · #10 07/15/2004, 01:28 PM

It gets a little contrived, since the SCWDS require 3/4". Not positive, but the M12 is 3/4" outlet. Even if it is 1" you would still have to come down to 3/4 at some point.

DonBossung · #11 07/15/2004, 06:05 PM

Guess I am basing my comments on sump experience that the size of the return does make a difference in flow. But, all that was with 5' head and a couple of 45 elbows. Not sure if that is as critical here.

BTW the mag 12 is 3/4" input/output.