Overflow vs big holes vs built in

[Salt4Us]

At our LFS, we could get good price on 60g acrylic for $150. The problem here is that it doesn't come w/ any intank overflows or anything. It's just a tank. I inquired about purchasing the tank w/ some intank overflows installed but the guy there said he'd drill big holes (about 2-3 inch holes) for outlet & inlet bulkheads. My question..is the bulkhead method better than built in overflows or built in sumps (the kind that occupy the back of the tank)?

Any thoughts & comments are welcome.

John

 

[reefrunner69]

I prefer undertank sumps to built in sumps. I think the drilled back is pretty much the same as a built in overflow, except you'll need more clearance from the wall. One thing about acrylic...it makes doing a closed loop a snap

 

[loganj]

Although the in-tank bulkheads are fine, I like an internal overflow better. One reason is it's a lot easier to crab/snail proof an internal overflow. One good sized hermit stuck in a bulkhead can spell disaster. The internal overflow also allows you to take your sump water from the very top layer of the tank which is where the DOC's are going to be. You could build the internal overflows with a couple of pieces of acrylic and some Weld On #16 very easily.

 

[reefrunner69]

Both issues noted by Logan are easily overcome using bulkhead strainers and elbows. The water would be surface skimmed and the strainers would keep critters out of the plumbing. IMO, it is strictly a space issue. As a matter of fact...look at ReefLady's album or the full tank thread, she has the back of her tank drilled rather than internal overflows.

 

[fishfreek]

If the guy will drill holes and it wont cost much extra then I say have him drill holes. If you put a pair of drain holes in the back and toward the edges and then have your return hoels where ever you want. THen you will hve to install the bulkheads and plumb as kevin mentioned with some elbows, etc so as to pull water from the surface. The more drains you have th emore protection will have from any one clogging and causing a flood.

Size the holes you need to have drilled based upon the size of the builkhead that you will need to use for the approprate plumbing. For example a 1" drainline might need a bulkhead hole of 1 3/4".

 

[Hara]

one word of warning...those things are notorious for the ease in which they get scratched up.

 

[Salt4Us]

So having the outs (to the sump) from the tank towards the ends would be better. Would having the ins (from the sump) be better toward the middle of the tank or a third of the way from the end be more beneficial for water flow (two outs, one on each end & two ins spaced in 1/3 of the way from the ends)?

For flow, would the LR be better in the middle of the tank or up against the back wall?

We're just concerned about flow & how to get the right flow going.

Thanks again!

 

[loganj]

I still like the internal overflow better...I think it skims the surface more efficiently because it takes a thinner layer of water from the surface of the tank. Does that make sense? The strainer will take care of critters getting stuck in the plumbing though.
I'm thinking that the drain on each end and the return in the middle would work well. You can, as reefrunner suggested, do a closed loop to balance your flow if you wish or you could use powerheads. The advantage to the closed loop is that most of it is out of site. The advantage to the PH's is that you can easily attach a wavemaker to modify your flow characteristics. The 180 I set up at the eyecare center has both.
FWIW, most of the tanks I've set up have had the drain/overflow in one corner and the return on the other side. This arrangement seems to work well too. One thing you'll want to make sure of...either keep your return outlet close to the surface or drill a siphon break in it close to the surface. If the pump quits, water will siphon back through the pump into the sump until the siphon is broken.

 

[reefrunner69]

I think it skims the surface more efficiently because it takes a thinner layer of water from the surface of the tank

That really depends on the size of the elbow used and the number of drains The thickness of the layer of water skimmed would be determined by the amount of flow and the size/length of the overflow. I think either is fne, but drilling the back will leave more room in the tank, not as much space taken by the internal overflow. It is also easier to service, IMO.

 

[loganj]

That really depends on the size of the elbow used and the number of drains The thickness of the layer of water skimmed would be determined by the amount of flow and the size/length of the overflow.

Very true. It would certainly work just fine. Another idea I saw, and I think this might have been in Anthony Calfo's book, was to drill the back of the tank and put a very short overflow with a weir across part of the back of the tank. This would give you the best of both...good surface skimming and very little loss of space in the tank. It would be easy to do with an acrylic tank too.
I have had some difficulties with tanks drilled in the back in the past which, I'm sure, has biased my opinion. However, I have to admit that the holes in those tanks were way too small and that was most of the problem with them. How does the saying go....Once flooded, twice shy...or something like that .

 

[reefrunner69]

Another idea I saw, and I think this might have been in Anthony Calfo's book, was to drill the back of the tank and put a very short overflow with a weir across part of the back of the tank. This would give you the best of both...good surface skimming and very little loss of space in the tank. It would be easy to do with an acrylic tank too.

This is what mojoreef did with his L shaped tank the overflow spans the entire length of the tank, it's pretty cool.

 

[wseaton]

On a related subject, what are the opinions of those hang on style siphon-over-flow gizmos that cost around $100 and allow you to add an overflow/sump to any basic tank??

A good friend of mine has been asking about them, and I have no experience if they work or not, or are reliable.

Y'all can keep the plexi tanks Been there - done that, and won't go back.

 

[loganj]

IME, they work just fine and you can get one for less than $100. The trick is to keep air bubbles out of the U tube. You can play around with the water depth in the outside box and usually keep the bubbles out. If you have enough flow though, the bubbles will be carried on through the U tube and won't cause a problem. The bubbles can build up in the U tube, if not adjusted properly, and cause the siphon to be lost.