DIY slim overflow

[justDIY]

OK ... this is the third overflow I've built, second I've actually constructed... learning a tad more every time, by the 10th or 11th overflow I think I'll have it down

my objective is to have an overflow that fits behind my tank, which is close to a wall, not leaving a lot of "width" available for a large drain box (found on most commerical overflows)

so I designed an overflow that is 12" long by 3" wide. It has two 3/4" drains and a 1.25" (or maybe two 1") siphon. my target GPH is ~400-500, not sure if two 3/4" will push that or not, especially since I'm using hose and not pipe. failing that, I should have enough room to ream out the holes for 1" drains.

so, here's so pics (more to come, ran out of good light)

 

[mono]

looks pretty sweet, where do you get those bulkheads, the ones at my local aquarium are like $20 each!

 

[loganj]

Two 3/4 drains should easily handle 500gph. I have a tank running with a 1200gph pump using two 1" drains and a 1 1/2" siphon tube. You may even find that you need more flow to make the overflow operate at max efficiency. I have another tank...doing about 200 gph there...where the DOC on top of the water never gets pulled into the siphon because there isn't enough flow through the overflow box.
Your design looks good to me. My guess is the "bulkheads" are PVC adapters?

 

[justDIY]

where do you get those bulkheads, the ones at my local aquarium are like $20 each!

My guess is the "bulkheads" are PVC adapters?

yea, what he said!

39 cents for the 3/4" Socket to Male Pipe Thread fitting

99 cents for the 3/4" Female Pipe Thread to Hose Barb fitting

$1.59 for a 3/4" O-Ring

so for under $3 I got a nice bulkhead - just wrap the threads with a little teflon tape and hand tighten till the o-ring is seated.

watch out however, that trick only works on 1/2" through 1" sized parts, once you go over 1" the pieces only thread together using teflon lubricant and heavy pipe wrenches.

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Guess I should add a complete rundown:

Approx $18 in Plastolite 1/8th Inch Acrylic Sheet
Approx $6 in "bulkheads"
Approx $10 in 3/4" hose (need to get more though)

Assembly time about 6 hours

 

[justDIY]

more pics

here's a shot of the drain box sans weirs and the skimmer box.

I may use stand-pipes (with a modified compact durso) and dispense with the weirs completely

I haven't worked out the perfect method of joining the two yet ... the skimmer box has that extra lip on it which I might try bending over, but 100% sure on how to do it yet.

 

[BillyZ]

I might try bending over, but 100% sure on how to do it yet.

got any spare 1/8" left over? you can try using a hair dryer on its highest setting (may take a while). Just set the box on its side with the part you want to bend hanging over the edge of the table. Heat... heat some more apply slight preassure on it while heating and see if it sags. If the hair dryer doesn't work you can also, if you have one or access to one, find a "heat gun" wich is like a hair dryer on steroids ) people that might have one:

Model Airplane enthusiasts
Car/Home Audio enthusiasts
Electronic enthusiasts (aka HAM radio operators ;o) )
Cusomt Chopper builders ('cause I see em use them on the discover shows! lol)

I've also heard of folks "baking" acrylic to accomplish the same thing.. but the fact that your box is already assembled makes that difficult at best. :?

 

[justDIY]

for my last overflow, I bent the sheet using my stove (electric), wearing leather gloves I held the section over the burner until it softened, and then formed the bend using a wood scrap.

however, this piece is too "long" to heat evenly over the burner properly, so as you mentioned, I might try some strips.

will have to stop off at the hw store, don't have any here ATM

 

[fishfreek]

Was the logic behind the two 3/4" drain lines to keep the width down?

 

[justDIY]

yea, to minimize the behind-tank space needed, but still provide some good flow ability.

actually 3" was more than enough for a 3/4" drain ... the hole needed to be about 1.125

so I could actually ream out and upgrade to 1" drains if I wanted to move this overflow to a larger tank, requiring more flow

the CPR and other brands all seem to be between 4" and 8" wide, which really sucks if your tank is right up to a wall ... so instead of short in length and wide in depth, I went long in length and short in depth

I just picked up the rest of the plumbing to make a pair of modified durso's as well as some plastic scraps to attach the boxes together. - will post more pics shortly.

 

[dansemacabre]

Cool

Awesome. I plan on building myself an overflow (I refuse to pay $100 for a box!). So I thought I'd ask, where is usually the best place to find acrylic? Thanks!

 

[justDIY]

I buy my acrylic from Ace Hardware ... although if I might get a table saw and buy it in sheets next time ...

ace does a terrible job of cutting the plastic - very rough edges and never even close to size I specify. (i mean, off by more than 1/8th)

sure you can sand out the imperfections, but then you gonna sand and measure ALL the pieces to make sure they're the same for corrected measurements...

The hard stuff to find is the Adhesive.

in Detroit, you can probably find an industrial store that sells it ... you want "Weld On #3" and "Weld On #16" from IPS.

 

[justDIY]

ok, I flow tested the drain box today using my 750 gph emergency pump.

with both ports open, there were no problems at all draining approx 640 gph (as I emulated some head pressure)

with a complete blockage, one port was unable to handle the flow. but that is OK, as the overflow is already exceeding my design goals.

you can also see my modified Durso standpipe design, which allows the box to drain silently!

 

[mono]

Alright, I've been f%#*ing around trying to find some bulkheads from hardware shops and plumbing supply stores for 2 weeks. I've had it, and I'm not paying $20 for the ones at the aquarium, they aren't even the ones I want.

JustDIY, what would you charge to build me one? Remember I'm an Aussie and our dollar is worth about 60 US cents???

I've bought a sump, a fricken powerhead to get the water back to the tank, but I can't get it out of the tank!!!

Please HElp!!!

 

[BillyZ]

now don't take this the wrong way... but your box is lookin good!

looking at your durso I notice no vent. Is that the "modified" bit of it? In your tests did they start without any trouble and flow well without the vent? In the iconic durso instruction page it mentions the size of the vent to be critical in proper flow and for starting the flow.

if thats not what's modified... what is? Inquirying minds need to know!

 

[justDIY]

@billyz

well, the only mod is that it is very "short" compared to durso, other than that, it is pretty much verbatim ... oh, I did not use a "street elbow" because it cost $2, I used a $0.39 regular elbow instead and a small piece of pipe to couple it to the Tee

NO problems with the overflow starting - I did notice a sudden inrush of water will cause a siphon effect, and make the overflow drain so fast the elbow comes out of the water and sucks air, but it fixes itself right away and goes back to being almost completely silent

at 280 gph (maxi 1000), the drains make no noise at all and the water outlets also make no noise

at 560 gph (2 maxi's), the drains make no noise at all, and the water outlets make a minor splashing sound

at 700 gph (emergency pump), the drains make no noise at all, and the water outlets make a noticeable splashing sound

at 980 gph (e pump + 1 maxi), the drains make no noise at all, and the water outlets sound like a a hose being sprayed into a bucket

at 1260 gph (e pump + 2 maxi), the drains are still silent! and the water outlets sound like niagra falls

I'm impressed that the overflow can handle such volume! Design goals were exceeded by 200%

With a single drain open, the overflow can handle the two maxijet's, but not the e-pump, so that would put the capacity around 600gph for one drain

here's a shot of the vent, it is either 1/16th or 1/32nd hole ... smallest frickin drill bit I have hehe

 

[justDIY]

Alright, I've been f%#*ing around trying to find some bulkheads from hardware shops and plumbing supply stores for 2 weeks. I've had it, and I'm not paying $20 for the ones at the aquarium, they aren't even the ones I want.

sorry to hear about your trouble finding parts! I know how that goes, the town I'm in is very small and it is frequently difficult to find anything "exotic" like tank plumbing pieces!

you talk about getting water out of the tank? for this you need an external overflow - the bulkheads are but a single part of the system, which allow the overflow to drain into the sump.

for bulkheads, here is my parts list:

3/4 inch socket (or slip or weld) to 3/4 inch male pipe thread
3/4 inch female pipe thread to 3/4 inch hose barb
1 inch rubber o-ring

I don't know if they use inches for plumbing in AU but these are all very standard parts, any store that sells plumbing pieces should sell them or something similar.

for the siphon U-Tube

1.25 inch 90 degree elbows two
2 feet of 1.25 inch pipe

I cut a small piece of pipe just long enough to join the two elbows together, and then two more pieces a bit longer to extend down into the skimmer box and drain box, to about 1.5" from the bottom.

for the overflow box itself, here is my cut list, all cut from 1/8th inch plexiglas
drain box: (goes outside the tank)

bottom----12 inch by 3.25 inch
front----12 inch by 6 inch
back----12 inch by 6 inch
2 sides----3 inch by 6 inch

skimmer box: (goes inside the tank)

bottom----12inch by 3.25 inch
front----4inch by 12 inch
back----6inch by 12 inch
2 sides----3inch by 4 inch


working with the plexi was something I put off for a LONG time. my first overflow built was plastic juice/food boxes connected together with a piece of plastic scrap. it worked for almost a year, and would still be working if I didn't break it screwing around.

people have built overflows using the small plastic "tanks" you get from the pet store to keep sick fish or betta in.

sorry but I can't build you one right now, I don't have the time. I'm happy to help with whatever information I can provide!

 

[BillyZ]

were those rates you quoted through any plumbing out of the standpipes or was that just a direct drain into your test bucket?

Do you think you'll lose much attaching plumbing?

btw... these are awesome flowrates for 3/4" plumbing... I think this is how i'll be handling the overflow for my tank.

btw... have we ever told you that you ARE the MAN?

 

[justDIY]

were those rates you quoted through any plumbing out of the standpipes or was that just a direct drain into your test bucket?

Do you think you'll lose much attaching plumbing?

Those were a direct drain right out the barb into a bucket. I think any loss incured by adding the hose would be negated by the fact that water picks up speed as it travels downhill, it also "pulls" itself along.

The bottle neck is in the bulkhead itself, and in any back-pressure the water might encounter at the end of it's journey in the sump (dumping underwater instead of above the water)

btw... these are awesome flowrates for 3/4" plumbing... I think this is how i'll be handling the overflow for my tank.

I was impressed too, but I think that an additional bottleneck will be with the siphon being able to deliver enough flow. I've measured a bit more, and will deff be going with either three 1" or a single 1.5" siphon, not a 1.25" ... I'm in the process of glueing the skimmer box and drain boxes together right now.