# Plexi Top Bowing???



## ToeTapper (Apr 10, 2009)

In the past I have had Plexi tops on aquariums etc... and it always has bowed on the corners and edges. Obviously this will let FFs and humidity out of the tank. I really want to use Plexi on a new build, but I want to know if anyone has a fix for this problem. i.e. thicker acrylic, reinforced edges etc.....

Thanks

Randy


----------



## Marinarawr (Jan 14, 2009)

I had that problem when keeping aquariums as well... You could certainly try sealing the plexi with marine epoxy or something to that effect but it would be much cheaper to just get a glass top. I think it has more to do with the heat from the lights than the humidity but it could easily be a combination of the two that breaks down the plastic's integrity. Either way, I personally gave up on plexiglass years ago.


----------



## gary1218 (Dec 31, 2005)

Try a plexi glass product called lexan. Home Depot carries it. I've had very good luck with it not bowing.


----------



## ToeTapper (Apr 10, 2009)

Gary

What thickness are you using?

Randy


----------



## gary1218 (Dec 31, 2005)

ToeTapper said:


> Gary
> 
> What thickness are you using?
> 
> Randy


They only have 1 thickness at Home Depot and I believe it was 3/16".


----------



## pl259 (Feb 27, 2006)

My take on plexiglass(acrylic) warpage is that it's mostly due to the difference in humidity between the conditions inside the tank and the conditions outside the tank. Acrylic doors on verts also warp.

My understanding is that acrylic is very hydroscopic. It likes to absorb moisture. As is absorbs moisture, it expands. The tank side of the acrylic sheet will absorb more moisture than the outer side, and it therefore will expand more. This is why the center of the sheet "bows" inwards towards the tank.

Lexan(polycarbonate) is less hydroscopic than acrylic. It still bows, but a lot less. 

Aside from changing to glass or polycarbonate, thicker sheets of acrylic will bow less, but still bow and are expensive. Other approaches I've seen involve adding a rib or two of material to mechanically control the bowing. This is usually only partially successfull. And as was already mentioned, you could seal the inner surface with something that would basically block the moisture from being absorbed by the acrylic sheet.


----------



## vugger#1 (Jul 20, 2009)

I use Lexan all the time. I have 4- 10gallon verticals and one 20 gallon vertical that I made the doors out of Lexan 5 months ago in they are not bowing at all. I made one for a 40 breeder lid that is 18" x36" and I put one cross support in it and that worked just fine and it even has 2 big doors cut in the middle of it. Mine is only 1/8" think. I will try to post a picture of it tomorrow for you.


----------



## boogsawaste (Jun 28, 2008)

I've also had good luck with polycarbonate. I've used 3/8" and 1/4". Warpage was minimal but I would recommend the 3/8 if you are covering a wide area. I have reinforced it with aluminum U channels before but only if I was having anything weighted right on top of it. Like a light or whatever. And I've only had to do it on an edge if it was covering a long area and not supported by the rim of the tank (like where a hinge would be on a lid).

For regular acrylic (personally I've used 1/16"), I have used weldon 16 to seal it to the plastic rim of an aquarium or top of an exo terra. This has worked great for me and I haven't had any warping issues.


----------



## ChrisK (Oct 28, 2008)

Anyone tried using U channel on plexiglass?


----------



## Philsuma (Jul 18, 2006)

The best method to clear and clean a top, side or front panel for viewing is a clean , new razor blade.

That said.....I only use glass and never have to worry about swirls or scratches.

just my pref....


----------



## UmbraSprite (Mar 2, 2007)

plastic bad
glass good


----------



## chinoanoah (Mar 9, 2009)

Get glass and call it a day. No need to mess with plastics in my opinion. Waste of time, money, and worries about frog safety.


----------



## ChrisK (Oct 28, 2008)

I was thinking more about Solacryl. So has anyone used U channel with acrylic?


----------



## Philsuma (Jul 18, 2006)

UmbraSprite said:


> plastic bad
> glass good


and a bit more green and eco friendly.

glass....it just "feels" better


----------



## Phyllobates (Dec 12, 2008)

Philsuma said:


> and a bit more green and eco friendly.


I can't argue with that. However acrylic does have advantages:

1. optically clearer
2. easier to cut/drill
3. less prone to hard water spots
4. better insulator.
5. shatter proof


----------



## Philsuma (Jul 18, 2006)

Phyllobater said:


> I can't argue with that. However acrylic does have advantages:
> 
> 1. optically clearer
> 2. easier to cut/drill
> ...


Not trying to be a goof with your list but just a normal discussion on the merits of plex vs glass right?

1. Not after it's all scratched, which you can bet is gonna happen with this hobby.

2. No argument there.

3. I don't follow this one...."prone"? In PA, there is VERY hard water. I have only one one rare instance, had a mineral deposit that was so fully into the glass where it resisted being leveled or scraped with a razor. Very rare IMO

4. Insulator...of heat? I do not want heat insulation in my vivs.

5. Safer....check.


----------



## Phyllobates (Dec 12, 2008)

Philsuma said:


> Not trying to be a goof with your list but just a normal discussion on the merits of plex vs glass right?
> 
> 1. Not after it's all scratched, which you can bet is gonna happen with this hobby.
> 
> ...


Not goofing at all. Those are excellent points. My counterpoints/clarification:

1. I've had some of my acrylic lids for almost a year now and the only scratches on them are the ones I put there when I made them out of scrap acrylic. But does acrylic scratch easier? - definitely yes.

3. Compared to my glass lids, my acrylic lids stay clearer with less deposits and lime. In other words they require less wiping.

4. Retaining heat would not necessarily be a good thing, but how about stabilizing temps? Less rapid fluctuations in temp seems like a good thing although I don't know if it would be a significant difference over glass in this respect.


----------



## Phyllobates (Dec 12, 2008)

pl259 said:


> My understanding is that acrylic is very hydroscopic. It likes to absorb moisture. As is absorbs moisture, it expands. The tank side of the acrylic sheet will absorb more moisture than the outer side, and it therefore will expand more. This is why the center of the sheet "bows" inwards towards the tank.
> 
> Aside from changing to glass or polycarbonate, thicker sheets of acrylic will bow less, but still bow and are expensive. Other approaches I've seen involve adding a rib or two of material to mechanically control the bowing. This is usually only partially successfull. And as was already mentioned, you could seal the inner surface with something that would basically block the moisture from being absorbed by the acrylic sheet.


Actually I find my center brace bows upwards. Strange and counterintuitive.

Excellent point about the ribbing/bracing. This is the key to avoiding/reducing warping imo.


----------



## ChrisK (Oct 28, 2008)

Phyllobater said:


> Actually I find my center brace bows upwards. Strange and counterintuitive.
> 
> Excellent point about the ribbing/bracing. This is the key to avoiding/reducing warping imo.


I'm planning on making Solacryl lids like I mentioned - would the ribbing be more effective than the U channels? I was planning on doing both - just wanna hear peoples' opinions


----------



## frogfreak (Mar 4, 2009)

Philsuma said:


> and a bit more green and eco friendly.
> 
> glass....it just "feels" better


I agree...glass...it just "feels" better

Is glass more green than plastic? 

I wonder what CO2 emissions would be like if we were trucking glass all over North America vs. plastic. 

Just a thought...


----------



## Phyllobates (Dec 12, 2008)

ChrisK said:


> I'm planning on making Solacryl lids like I mentioned - would the ribbing be more effective than the U channels? I was planning on doing both - just wanna hear peoples' opinions


Chris are you talking about inserting the solacryl into the U channel or welding the U channel on perpendicularly? I would say the latter would work but not the former. I'll try to post pics of some of my lids later tonight.

Chris


----------



## Phyllobates (Dec 12, 2008)

10 gallon top made 0.100 in acrylic - no warping








40 breeder top made of 0.220 in acrylic- slight warping, need some lengthwise center braces I think.








The top of my 120. Before I put the braces on in was bowing up almost an inch in the center. Now I have a very slight bow but its manageable.


----------



## Philsuma (Jul 18, 2006)

Good lord...*multiple* Braces on tops??? 

Glass is so much easier.


----------



## ChrisK (Oct 28, 2008)

Phyllobater said:


> Chris are you talking about inserting the solacryl into the U channel or welding the U channel on perpendicularly? I would say the latter would work but not the former. I'll try to post pics of some of my lids later tonight.
> 
> Chris


Yeah I was thinking about sliding U channel onto all 4 edges of the solacryl like a frame, then maybe gluing some thick strips of acrylic along the length on top more towards the middle to brace it.

How do your braces work there?


----------



## Phyllobates (Dec 12, 2008)

Philsuma said:


> Good lord...*multiple* Braces on tops???
> 
> Glass is so much easier.


Lol yes. That, I would have to admit, was a huge pain in the a**. I had about 20 clamps on the top of the tank trying get the bow out so I could solvent weld the brace on.

Clearly I'm not gonna win you over on acrylic anytime soon huh


----------



## Phyllobates (Dec 12, 2008)

ChrisK said:


> Yeah I was thinking about sliding U channel onto all 4 edges of the solacryl like a frame, then maybe gluing some thick strips of acrylic along the length on top more towards the middle to brace it.
> 
> How do your braces work there?


I think the braces work well provided you use thick enough material and don't span too large an opening. What thickness is your solacryl and how large of lids are you making? And where the heck did you get it? I can't find anyone to sell me a reasonable amount of it (less than a truckload).


----------



## Occidentalis (Jul 11, 2009)

frogfreak said:


> Is glass more green than plastic?
> 
> I wonder what CO2 emissions would be like if we were trucking glass all over North America vs. plastic.


Glass is the only material (to my knowledge) that can be recycled an infinite number of times. It also uses less energy to recycle glass than make it from raw materials. Unfortunately, plate glass like we use for the tanks isn't easily recyclable. 

Glass also isn't made from petroleum product, but is made from sand, soda ash and a pinch of limestone.


----------



## ChrisK (Oct 28, 2008)

Phyllobater said:


> I think the braces work well provided you use thick enough material and don't span too large an opening. What thickness is your solacryl and how large of lids are you making? And where the heck did you get it? I can't find anyone to sell me a reasonable amount of it (less than a truckload).


Yeah after months and months of searching, I finally found a distributor in MY TOWN.  
.118" thick, for the exo terras and zoo meds I'm going to take the screen off the frames of the tops and just solvent glue it onto those like Marty did on his website ( http://www.mistking.com/Exo-terra-Misting-sp-10.html ) so that should be ok, but I got some aquarium style tanks of different sizes also that I need them for, there's going to be screening and I guess maybe a hinge type opening on the top too so the whole tops won't be solacryl - maybe half of the top of a 44 gallon corner pentagon and parts of the tops of a bunch of 65 gals, maybe some others


----------



## Phyllobates (Dec 12, 2008)

ChrisK said:


> Yeah after months and months of searching, I finally found a distributor in MY TOWN.
> .118" thick, for the exo terras and zoo meds I'm going to take the screen off the frames of the tops and just solvent glue it onto those like Marty did on his website ( MistKing :: Exo-terra Misting ) so that should be ok, but I got some aquarium style tanks of different sizes also that I need them for, there's going to be screening and I guess maybe a hinge type opening on the top too so the whole tops won't be solacryl - maybe half of the top of a 44 gallon corner pentagon and parts of the tops of a bunch of 65 gals, maybe some others


Yeah I think you'll be good on the exos. For the bigger tanks you'll definitely need to do some bracing with at least 1/4" stock- around the outside rim and across the center lengthwise. Unless its similar to lexan in rigidity... Haven't worked with it so I can't exactly say. Good luck!


----------



## boogsawaste (Jun 28, 2008)

I'm still a fan of polycarbonate. Using it pretty thick I haven't had any problems with it. It's easy to cut and drill for me. But I don't have anything against glass either except for those reasons I stated. So in the end whatever I have is what it gets.


----------



## Dancing frogs (Feb 20, 2004)

ChrisK said:


> Anyone tried using U channel on plexiglass?


No, but I recently found a piece of 90 angle aluminum bolted to the plexe eliminates the issue.
Very easy to do as well.


----------



## ChrisK (Oct 28, 2008)

Dancing frogs said:


> No, but I recently found a piece of 90 angle aluminum bolted to the plexe eliminates the issue.
> Very easy to do as well.


Really, where do you bolt it in relation to the edges etc? Can't really picture what you're talking about


----------

