Using acrylic for coast to coast overflow?

[redcoatd]

Hi,

I'm planning to build a coast to coast overflow on my 75 gal glass tank (but along one side, perpendicular to the length of the tank due to the stand I inherited).

I purchased the acrylic and was all set to start building, but read that acrylic can expand in water? Thinking that might not be a good thing on a C2C...

Thoughts?

cheers

David

 

[dattack]

What are you afraid might happen? It should be fine considering a few of the kits are sold using acrylic and most overflow boxes are made of acrylic.

 

[mcgyvr]

moisture absorbtion/humidity issues with acrylic are really only an issue with unrestrained pieces or super critical tolerances. An acrylic overflow should not experience any serious issues due to it and its done all the time.

Now how you build it and attempt to secure it in place can be a problem.
Its best to build a 5 sided box with holes drilled in the back and support it with your bulkheads by passing them through the holes versus trying to attach it to the glass with adhesives/silicone which is prone to failing as there is very little that will provide a proper bond between glass/acrylic.

 

[redcoatd]

This is what triggered my concern!! http://www.reefcentral.com/forums/showpost.php?p=23397892&postcount=4

I am building a coast to coast for a penisula-type set up (on the right hand side). I want to hide the fittings inside the overflow, so I was going to use black acrylic. But if I build it truly c2c and then it expands, I was scared by that pic above....

cheers

David

 

[SGT_York]

Easy to shorten the overflow a few inches on each side which also gives you a good location to run your returns. It will also add to your overflow length as well. You will need two small additional pieces to fit on the ends (obviously)

 

[ca1ore]

Yeah, just build a five sided box that has a bit of clearance on both ends. Acrylic will expand in water (I believe) but will only warp if there is differential humidity on the two sides (which in this case, there will not be).

 

[sleepydoc]

+1
If you are doing a true coast to coast I would make it out of glass to avoid the expansion/cracking issues you've expressed. If you are just making a long overflow box that doesn't extend to both ends you can use acrylic without issue as others have stated.

If you use the 5 sided box approach, make sure to either put the bulkhead flange on the outside of the bank or add a gasket between the overflow wall and the tank wall.

 

[redcoatd]

Thanks all...

My main concern is making the overflow dark so the plumbing in there is not seen, especially at the front.

I guess I could glue the acrylic to the glass? Seems a lot of extra work

cheers

David