4300 Gallon Plywood Build (3600+ Take 2)

[lilolmedn]

Wow I love this thread =) Subscribed!!

 

[CJH]

EXTREMELY BAD ADVICE! It is well-known that extruded is NOT strong enough to hold the pressures of larger aquariums.

There are two basic types of acrylic: extruded and cell cast.

Whoah, Pete. I never gave the advice to use extruded acrylic. Please show me where I did and please don't get so defensive without reading more closely.

I did suggest extruded polycarbonate could work. It would be far from my first choice but if given a free sheet that wouldn't be exposed to UV I would use it.

I will say, however, that there are cell cast acrylics that aren't any better than extruded acrylics. Or at least that they aren't "enough better" to be used in a tank.

Again, I would never go out and buy lexan or other polycarbonate for a fish tank. But if given free pieces I would consider it.

 

[CJH]

I have 3/4" pc (poly carbonate) available to me at a very very cheap price. I want to experiment with it. Pete, how big do you think I could go with a piece of 3/4"? What's your opinion CJH?

I'll be brief and say my only concern with a piece that large is that it will likely bow more than good quality acrylic of the same thickness. The concern then is the stress it will put on whatever you used to seal the panel in place.

I have some contacts at a large public aquarium. They got a bunch of free polycarbonate and used it for windows on their holding tanks behind the scenes. I'll see if I can get some hard data for you. I'll just PM it to you if you don't start another thread.

 

[nolapete]

CJH,

Extruded polycarbonate is more than strong enough for a fish tank.

is hardly not giving advice to use it.

I'm not getting defensive at all, but I'm not going to sit here and let someone propagate bad information either.

 

[nolapete]

ok, everyone chillax.... Large tank construction is a vauge term don't ya think? Large is a matter of opinion. I have 3/4" pc (poly carbonate) available to me at a very very cheap price. I want to experiment with it. Pete, how big do you think I could go with a piece of 3/4"? What's your opinion CJH?

Keep in mind I have no idea if this stuff is imported or not. They are 8'x42" scraps.

(sorry to derail pete, if you would like me to start my own thread I will)

I don't mind the discussion Jonathan.

The statement about imported refers to cell cast acrylic, comparing US standards vs. foreign. I didn't make that up. Just copied it verbatim from another site. (not an aquarium site)

Look at Rich's (VLDesign) tank. He uses 3/4" glass, so a tank similar height and width would be a good test. The pressure is the same no matter what the measurement is front to back (hydrostatic paradox), so you don't have to build it 1500 gallons to test it. I wouldn't go over 36" tall with it though. You could try it, but I think you'd be doomed from the get go.

Build your tank, install the polycarbonate, put a pond liner in the tank, test fill. If it works, drain, take out pond liner, then coat tank with pond coat/rubber coat. That way you don't waste sealant when it explodes.

 

[CJH]

CJH, is hardly not giving advice to use it.

I'm not getting defensive at all, but I'm not going to sit here and let someone propagate bad information either.

And I asked for an example of where I recommended extruded acrylic, not extruded polycarbonate.

You seem to be comparing the two based on whether they are extruded or cast. What I'm trying to get across is that nowadays there is so much variety in domestic vs. imported clear plastic sheets that we can no longer make discrete categories such as "cast is always better than extruded".

When it comes to acrylic vs. polycarbonate we have to compare the two materials for what they are and not necessarily how they are made.

If you want to make the point that extruded acrylic (whether foreign or domestic) is not sufficent for aquaria building then I agree. But if you then want to carry that onto say that any extruded material is bad because extruded acrylic is bad, well then I disagree and would say that is propogating bad information.

But ultimately we agree on a couple of points: domestic acrylic is better than most any import and if comparing chemically similar plastics from the same manufacturer cell cast is better than extruded.

Personally I think polycarbonate, whether cast or extruded, is a poor choice for aquaria. It's more flexible, hard to polish, has relatively poor optical qualities and is more senstive to UV rays. But if given access to free sheets I'd sure as heck give some hard thought about using it.

 

[TheFishGuy]

The sheets are not free... But are very cheap. I get my poly carbonate from a scrapper for about $1 a pound. It doesn't matter if you get huge pieces (if you can find them) or a semi load of dust. You pay by the pound. I make custom lids for people in my club for their tanks. I really don't make much money on them... But going to buy the scrap every once and a while I run across these huge sheets and hide them! LOL For my purposes i could care less if they are scratched... I'd just be making large holding tanks...

Pete, I like your idea of using a pond liner! LOL especially the last comment! LOL Literally made me laugh out loud!

As for you guys and your heated debate. You might as well stop now because (correct me if I'm wrong) neither of you have tried using poly carbonate first hand. I would like to hear from someone who has, or links to where people have tried and failed...

 

[nolapete]

I didn't even have the heat on

The process of cast vs. extruded, regardless of which material, warrants consideration. Extruded materials will always be softer and/or inferior in strength to cast materials. i.e. cast iron, cast concrete, etc.

 

[TheFishGuy]

Oh c'mon... that response was BS and you know it! LOL (keep in mind I'm envisioning this conversation in either your fish room or mine over a bottle of suds)

 

[nolapete]

Actually it wasn't, but hoping to have that opportunity to in November. Planning on going to the OCA Extravaganza.