8x4x2.5 plywood planning in progress

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turtles

turtles

Candiru
MFK Member
Dec 28, 2012
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Australia
OK so I was originally going with a preformed pond but have decided I want a large viewing window so here I am going to have a crack at building a plywood tank 8x4x2.5
So I have a few questions
I plan on using 25mm plywood for the bottom and sides but the top brace was thinking 18mm to save a few bucks will this saving make a huge difference in strength?

I will be doing a 2x4 external bracing
I was thinking 15mm glass will this be enough? I'm doing 4 to 5 inch overlap all the way around will this be enough ?

I'm going with 150mm wide fibreglass strips for corner bracing and will be using pond shield for sealing as I have heard good reviews with the pond shield do I have to sand each coat for the next and does this do well with silicone is it easy to stick the glass down?

This is my first go at it my budget is 2k since materials here in Oz are not that cheap

Filtration is a experiment Im going with hopefully a 5x14x18 tank bio balls alot of cermic media purigen and some k1 or I may scrap the k1 for more ceramic I'm thinking a flow of 12500 litres per hour I believe that is 6x turnover rate of the tank give or take

This will be set up in my garage and I'm picking up plywood in a week or 2

Turtles
 
Just built a tank about the same size, im going to use american measurements I used 3/4 birch plywood all the way around with 2X4 bracing and a 1/2" thick 30" tall viewing panel almost 8' long. I used pond shield I sanded the wood with 60 grit then put the first coat down, let it cure 24 hours then sanded 60 grit. I then did the seams with fiberglass cloth laying the pond shield thick then putting the cloth down, added more pond shield and used a bondo paddle to smooth, then after 24 hours I lightly sanded the seams applied another coat then after about 3 hours when it was tacky I applied a third coat a little thicker
 
I am going a little heavy on the top bracing, im using left over plywood flush with the tank in strips around the edges and across then 2X4 over top connecting the front and back 2X4s
 
Niners4952 said:
Just built a tank about the same size, im going to use american measurements I used 3/4 birch plywood all the way around with 2X4 bracing and a 1/2" thick 30" tall viewing panel almost 8' long. I used pond shield I sanded the wood with 60 grit then put the first coat down, let it cure 24 hours then sanded 60 grit. I then did the seams with fiberglass cloth laying the pond shield thick then putting the cloth down, added more pond shield and used a bondo paddle to smooth, then after 24 hours I lightly sanded the seams applied another coat then after about 3 hours when it was tacky I applied a third coat a little thicker
Click to expand...
Feeling safe for the plywood thickness as I believe its 1 inch thick and glass is 3/4 OK I'm going to do 2 coats first then the fibre glass seems real thick and then another 2 coats of pond shield I'm buying 1.5 gallons I believe that is more then enough?
 
I ordered 1.5 gallon kit to be safe and it turned out to be a great idea, watch pond armors videos on their website as well as King of DIY 370 build. I did 1 coat let it dry for 24 hours then did the seams. I used a brush applied a thick layer of pond shield then layed the cloth down, used the bondo spreader to get it tight and even, then more pond shield then spreader again to even the pond shield, found it to not be as difficult as I thought, will try and post some pics for you
 
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First pic is plywood together, second is first coat then the seams, then second and third coats

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Niners4952 said:
I ordered 1.5 gallon kit to be safe and it turned out to be a great idea, watch pond armors videos on their website as well as King of DIY 370 build. I did 1 coat let it dry for 24 hours then did the seams. I used a brush applied a thick layer of pond shield then layed the cloth down, used the bondo spreader to get it tight and even, then more pond shield then spreader again to even the pond shield, found it to not be as difficult as I thought, will try and post some pics for you
Click to expand...
Niners advice is spot on, plywood is way stronger than most people give it credit for. Not to derail but your progress is looking great niners!
 
Wow looks great! how much overlap did you have on the piece of glass and plywood will 4inch be enough all the way around I'm going to do my drawings and sizing and get my plywood ordered and cut in the next fortnight thanks everybody for the help so far I will be back for more advise :)
 
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