Built-on Overflows

[Anonymous]

I constructed a very small overflow box out of acrylic. I screwed a threaded 90 degree PVC elbow into the bulkead inside the tank pointing downward. I then siliconed the overflow box inside the tank over the elbow. I plumbed this line, externally, like Rich's standpipes.

So has the silicone bond between the glass tank and acrylic overflow box held?

I would strongly consider using glass to build the overflow box if you have a glass tank. There's really no reason NOT to build the overflow out of glass since glass shops will cut the glass to size for you (and probably for cheaper than the acrylic would be before the cuts!). Acrylic/glass bonds are an accident waiting to happen IMHO, and if a leak occurred in this situation it could drain a substantial portion of your tank. The stress placed on the bond by the weight of the overflow plumbing should be mitigated as much as possible via PVC pipe holders as well.

My 2 cents...

 

[ChrisRD]

Just to clarify, the acrylic overflow box I was referring to in this thread was an internal overflox box. IME silicone is fine for holding these in place as the bond is really not under much pressure. For an external box on a glass tank, I would construct the box out of glass per Matt's suggestion...

 

[jandree22]

thanks guys, I understand both your points concerning the silicone. I would probably go with the internal box.

And with the internal box, I assume that it would be best to have the teeth level a bit higher than the top of the horizonal PVC, thus creating a lower water level in the overflow box than the tank, for two reasons. 1) This would actually create an overflow effect, effectively sucking in all of the surface skum and 2) it would create upward and outward pressure on the overflow box assisting with supporting it against the tank. Granted, wouldn't want to make the difference too much if for no other reason then preventing too much noisiness from "water gurgling".

 

[Anonymous]

something like this?

 

[jandree22]

yup, exactly. Very similar to Chris' example on the first page.

Also, I guess I should learn how to use that google 3d modeling software if I'm serious about plotting everything out.

 

[Mthompson]

I think that installing that 90 degree elbow (as in ChrisRD's picture)would cut back substantially on the gurgling noise. This is because the water level inside the overflow box would be above the bottom of the elbow, muffling the noise of the water flowing down the pvc outside.

ChrisRD...did you have any problems with a vacuum forming in the tube? If so did you mediate it by drilling a small hole in the top of the elbow?

 

[jandree22]

I think that installing that 90 degree elbow (as in ChrisRD's picture)would cut back substantially on the gurgling noise. This is because the water level inside the overflow box would be above the bottom of the elbow, muffling the noise of the water flowing down the pvc outside.

Very good point... I'll have to remember that detail.

 

[ChrisRD]

Yeah, the idea was to keep the intake submerged and yes there's an air bleed hole - basically it's just a Durso setup with the plumbing outside the tank.

Here's what I did on my most recent tank - working very well so far (I think it's about 6 months now)...
http://www.reefs.org/phpBB2/viewtopic.p ... t=overflow

 

[Anonymous]

Just to clarify, the acrylic overflow box I was referring to in this thread was an internal overflox box. IME silicone is fine for holding these in place as the bond is really not under much pressure.

Yeah, what you said.

 

[bleedingthought]

Oldie but goodie, huh?

 

[jandree22]

Oldie but goodie, huh?

Search button FTW! :wink: