closed loop hole distance

topofsteel

Member
I'm drilling my tank for a closed loop system. How far from the edges of the tank should I drill them? I was thinking 3" from the top and sides. And 5" from the bottom, because of the sand bed. Thoughts? Thanks.
 

acrylic51

Active Member
Really I think a lot comes down to personal choice....I tend to think you'd want your drains for you CL somewhat hidden, since they are going to be bigger than average bulkheads.... Usually people will either put the drains in the bottom of the tank hidden in rock work or mid way on the back panel of the tank. I had a bit of a discussion with someone today about the very thing on my build. I'm debating the layout of the holes....Hidden in the rock work seems like a novel idea, but if you can't easily access them it makes it hard.....Placed on the back panel of the tank, they can be hidden with rock work, but easily accessed if the need would arise.....
I'm curious as to you theory on placing the drains in the in the bottom corners and the returns in the upper corners....To maximize your returns you could position them in a way that you could use your tank walls to bounce/move flow more efficiently inside the tank....
May I ask what pump you've chosen for your CL? Bulkhead sizes as well?
 

topofsteel

Member
1" bulkheads, mag-drive 2400 gph and a 1" SCWD wave maker. I do plan to have rock work covering the intakes. The return from the overflow, which is centered on the back, come over the overflow and let out on either side at the bottom of the tank. I will have 20 degree elbows on the loop outlet's to direct the water downward across the front of the tank. My question was from a structural standpoint regarding the glass and and I wanted to maximize the flow of water. I hadn't thought about hiding the inlets. I will probably move them closer to the center. Thanks.
 

acrylic51

Active Member
I don't see any reason you can't drill the tank 3" from the top, but might bump it in a tad.......5" could work from the bottom of the tank as well. Any reason you chose the Mag24 and the SCWD???? Curious as to the size of the tank as well?
 
S

saxman

Guest
FWIW, the "cut off" from most tank builders is 2" from the edge of the glass. Of course, more space gives you a bit of "fudge factor".
I usually run my CL returns 6" from the bottom, which is perfect, assuming a 2" sandbed.
 

topofsteel

Member
It's a little more than a 100 gallon (5'x1.5'x2') with a 55 gallon sump. I was going for as much flow as I could afford. I believe the pump and the SCWD both have 1" in and outlets, so I went with 1" bulkheads and PVC. I had the tank set up several years ago, and bought the equipment 8 months ago or more, I'm just getting back to the build. I have been about to drill the tank for some time now. I'm probably going to drill 3" from the top and 6" from the sides an bottom, I'll post build pics.
What is your CL setup going to be? Tank size?
 

geoj

Active Member
Are you planning on small fish and if so are you making the drains large as to not have great suction?
 

topofsteel

Member
No, i would like a lionfish and a 'Popeye Catalufa Soldierfish'. I could make the intake as large as I need. Should i restrict the flow or get a smaller pump? I will have ball valves at all of the in and outlets if i need to replace the pump or whatever.
 

acrylic51

Active Member
I'd opt for 1.5" for your CL drains.... Go bigger and keep the pump constantly flooded. There won't be mad suction on these ports, so not a big concern, but you could get screens from Lowes or HD and trim them to fit flush inside the bulkhead. I'd also suggest using sched 80 bulkheads instead of sched 40. Better quality bulkheads IMO.
Personally I use 2 2" drains on my CL, and the output ports will be 1". They will be connected to an OceansMotions. I'd also suggest you let the flow of the pump wide open. Using 1" returns you'll have good flow, and that's where planning layouts of your return come into play.
 

topofsteel

Member
My logic was that the SCWD was going to be the limiting factor. Since the system is going to be alternating it's return, one at a basically. So two 1" drains will be supplying one 1" return. I'm curious about the screens from Lowe's or HD you mentioned? I had planned to use the conical screen caps that fit into the bulk head. Or a 90 degree elbow and a short pipe to pull water further from the sump return.
 

acrylic51

Active Member
It can be done with 1 drain, but redundancy is better. If that drain were to clog or close that would take your pump out. I'd be more concerned with heat transfer of the Mag to the tank water.
I know the grates your talking about. The ones I had mentioned at Lowes are in the section/area where shower drain stuff is. They are plastic and could easily be painted whatever color to match the bulkheads as well. If for whatever reason you couldn't find 1 to fit you can always buy a larger 1 and grind the outer ring down, and you slowly grind away unwanted material till you have the size you need. I will get a pic of them for you after work. I might have a pic of how I ground them down for a flush look on my PC at home. Will try to locate that pic for you as well!!!!
 
S

saxman

Guest
Hmmm...I thought I posted a pic of the spa screens I use. I have them in 1" and 1.5" IIRC.
I don't have a pic of an uninstalled one, but if you look in the center-left back of this tank, you'll see one. They just screw into the BH, and the black color matches the black tank back.

Here's the hole pattern:
 
Top