mrPrrr

Question about plywood tank

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Hello. Recently i found interesting and comprehansive article about school RAS system construction (fisheries.tamu.edu/files/2013/09/Model-Aquaculture-Recirculation-System-MARS-Engineering-and-Operations-Manual.pdf). There are some problems with translation. Could anyone explain me what does mean "fiberglass resin" (Figure 4 in article) ? Is it epoxy+fiberglass, fiberglass tissue mixed in epoxy resin or fiberglass tissue mixed in polyester resin?

 

What does mean "4 - 2 x 4's" ?

Edited by mrPrrr (see edit history)

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Greetings MrPrrr.

 

It seems that the publication you are reading might contain some North American English terminology (American/Canadian). The term "2x4" or "two by four" is a common way of describing a piece of lumber used for structures that is 4 inches wide by 2 inches high with various lengths.  I'm sure that you have a similar kind of cut of lumber in your country.  To make life a little confusing, the measurement refers to the dimension of the lumber when it is first cut.  When it is dried, it shrinks and is usually about a half inch smaller in height and width.

 

https://en.wikipedia.org/wiki/Lumber

 

Refer to the section on "Dimensional Lumber"

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Thanks. I understood - 4 units of girdle with dimentions - 4x2"

What about "fiberglass resin"?

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I remember reading that several years ago.  The resin they referred to was an epoxy resin.  I had looked at that, but the cost of epoxy was actually greater than purchasing a liner in my area.   It's been several years since I looked into it, but there was a special  grade of  epoxy used.  There was a cheaper resin, but it had issues with delaminating with constant submergence with water, so you will need a resin that is designed to be underwater.   

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The resin they referred to was an epoxy resin.

I think, that "fiberglass resin" is an epoxy primer for fiberglass tissue soaking. It's the first layer, and after, waterproof epoxy paint.

 

Early, i read website - www.jonolavsakvarium.com/eng_diy/tankbuilding2006/index.html - about composite plywood aquarium. Author used more cheaper polyester resin for soaking fiberglass tissue, and after as the second layer, coated waterproof epoxy paint.

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You're better off purchasing a a plastic tank or using a liner. Been there done that. Not worth the trouble using epoxies and resins IMHO, not to mention the cost. The thing I found out about epoxies is they all break down over time. All it takes is a pin hole and once the water works it's way under the resin it just gets worse. 

 

The KISS principal applies here (Keep it Simple Stupid). 

mrPrrr likes this

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Hi

I tend on agree with on cost Cecil, however if done "properly" hard to beat reinforced epoxy IMO

I still have/use a 45+ years  old dingy & cano made out of epoxy/fiberglas/plywood my father bought/gave me, as a kid. I'w had/used, 2 inflatable zodiacs, both lasted about +/- 15 years, made of EPDM rubber, with plywood/epoxy/aluminum floors (they where still fine when I scraped them).

The "new" boat I bought this spring is made in 1983 made out of sandwiched epoxy/fiberglass/plywood, still not soaking water.

So my experience with epoxy, regarding it breaking down over time is opposit of Cecil's.

Jon Olav is also pointing out the potential epoxy pitfall in his aquarium blog http://www.jonolavsakvarium.com/eng_diy/epoxy_test/article.html

 

cheers

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