External horizontal overflow

bingoreefer42 · #1 08/22/2005, 02:36 PM

AC : How do you find time to answer questions here and at wetwebmedia? Amazing.

I wish to implement your idea of a horizontal overflow but on the outside of my tank (hence the subject line.) It's a 135 acrylic, 3/8", 72" long and 24" tall and 18" front-to-back.

I'd like to create an overflow the entire length of the tank, obviously cemented to the rear. The height and width of the overflow box will be based on a.) the diameter of the 2" bulkheads that go in there and b.) your advice.

Also ... my idea to create the opening(s) for the overflow are to drill many holes or slots along the entire width of the tank back.

I guess my question here is to ask for any advice on this idea ....
Thanks,
slc

Steven Pro · #2 08/22/2005, 03:02 PM

I believe moonpod did something very much like what you describe and I think he has pictures of it in his gallery.

Anthony Calfo · #3 08/22/2005, 06:05 PM

It may serve other purposes very well... but does defeat the biggest advantage of an internal horizontal internal overflow: the thinning of surface extracted water over a weir/wall.

Instead, your external will be fed the same amount of water by a few bulkheads that are extracting a thicker slice of water (and less concentrated proteins to do it).

The only way around this (easy on acrylic, but not post-production glass tanks) is to rout/grind down that back wall of the aquarium so that it serves as a spillway pouring into the ext. overflow trough. This will capture your "thinner" water for better protein skimming.

Thank you for your kind words too, SLC

Anthony

bingoreefer42 · #4 08/22/2005, 07:48 PM

Steve : Thanks for the moonpod tip. Looking stuff over now.

AC : Oops, I must have described my plan in a muddled fashion - the builkheads are to drain the overflow to the sump and closed loop pump, and the holes or slots I want to create get the water out of the back of the tank into the overflow...aka the spillway.

I will try and look for info on the spillway creation .... looking for advice on the dimensions or spacing, structural things to keep in mind, etc.

Thanks again for responding!
slc

Anthony Calfo · #5 08/22/2005, 09:40 PM

ah, understood

Agreed.

I may have been reading too fast today too. Arghhh!

Anthony Calfo · #6 08/22/2005, 09:46 PM

with it being acrylic... the slotting will be just fine. This ext. horizontal overflow will work as intended plus have the advantage of not taking up space inside of the tank. Fab

Chihuahua6 · #7 08/23/2005, 07:54 AM

Yes Moonpod did a great job with his. I plan to have my acrylic tank made with an external overflow as well. I know someone had Envision Acrylics make their tank this way and they posted pictures of it. I don't remember who though. It was a month or so back that I saw it. Maybe in the large tank forum? Has anyone seen it?

Chihuahua6 · #8 08/23/2005, 09:18 AM

Here are some links with pictures. One is acrylic and one is glass:

http://archive.reefcentral.com/forum...ernal+overflow

http://archive.reefcentral.com/forum...hreadid=584289

cward · #9 09/02/2005, 03:05 PM

Here is a pic of what I did.

cward · #10 09/02/2005, 03:11 PM

Here is a better pic of the plumbing. The two 2" pipes are the drains, and the third drain is a feed for my skimmer. It's been running for several months now and I like the design a lot.
The overflow box is 30"X6"X18".

bingoreefer42 · #11 09/02/2005, 03:39 PM

Great design and implementation! Thanks for the pics.
BTW : what is the max overflow rate that you estimate this setup can handle?
slc

cward · #12 09/02/2005, 07:41 PM

I haven't calculated anything, but I have a Sequence Hammerhead that I've ran full throttle thru 3 returns and the water only makes it half way up the overflow slots.

ktani · #13 09/02/2005, 10:37 PM

Cward, that is excellent information. Thanks.

I am setting up a 600 gallon 96 x 48 x 30 and using the left side of the tank with a similar setup. It has an external box with 4 holes. I was thinking of using one for a drain, two for chases for the closed loops and another for the closed loop drain.

My concern was am I pushing too many of the proteins back through the closed loop instead of through the skimmer, thus defeating the purpose of removing the surface water.

Anthony, your thoughts?

Kip

Anthony Calfo · #14 09/02/2005, 10:43 PM

The turnover does not have to be very high in such typically small (volume) overflows to be very effective. Most designs fall this way and work without a hitch.

As for the CL manifold... its not much of a problem IMO as long as it is not badly agitating the surface, but rather has effluents releasing below it, as most designs indicate (this also reduces salt spray and salt creep issues).

kindly,

Anth-

bingoreefer42 · #15 09/09/2005, 02:05 PM

Cward : If you can run a Sequence pump of any size and only get 1/2 of the vertical height of your overflow to 'bunch up' with water with what appears to be 48" of overflow slottage ... then that helps me trim down my overflow design to much less than it is now (72", length of the tank.)

I wasn't looking forward to an entire weekend of routing acrylic slots !

So, thanks for the empirical feedback -

bingoreefer42 · #16 09/09/2005, 02:07 PM

Oops, I mean 30" of overflow slottage .... even better.

cward · #17 09/09/2005, 02:15 PM

Quote:

Originally posted by bingoreefer42
Cward : If you can run a Sequence pump of any size and only get 1/2 of the vertical height of your overflow to 'bunch up' with water with what appears to be 48" of overflow slottage ... then that helps me trim down my overflow design to much less than it is now (72", length of the tank.)

I wasn't looking forward to an entire weekend of routing acrylic slots !

So, thanks for the empirical feedback -

Don't know if this helps, but my slots are 7/16" X 1 1/2".