900 gallon plywood shark tank build

slowpoke92

Feeder Fish
MFK Member
Apr 1, 2020
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This looks too daunting for me to make but I'm excited to see more of your work progress.
 

dingodan

Jack Dempsey
MFK Member
May 11, 2014
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vancouver bc
Did you wet lay the cloth? When I did mine I did not, I used 3m adhesive and put cloth down and then went over it with resin. I struggled with tiny air bubbles. I sanded the couple bubbles I had out and laid a small patch of cloth and resin. But man pin holes and micro air bubbles 🤯🤯🤯🤯. I had one that took 3 days to find, was literally the size of a pin head, only way I found it was my light hit it just right. Yours looks very good so far. I had 1 spot that didn't look like any resin was even on the cloth but is as smooth as glass, thought that was odd. As far as thickness of resin, I did 4 coats of resin with a sanding in between to get all the high spots down. It's like a piece of glass now inside. 4 years later after a dozen leaks when I first got it up, it's doing well.
I precut my cloth and used nails to pin it to the top of the tank so it wouldnt sag. Then flipped it up, rolled a coat of epoxy over the wood, then flipped the glass down and rolled or brushed another coat of epoxy over the cloth (i used the brush until i finally discovered at the end the roller gets a way more even coat) . I then rolled it out with an alluminum fin roller. I didnt have much issue with air bubbles but when i did i used a heat gun while the epoxy was wet to get them out. Im not over concerned about the small amount of air bubbles i currently have as ive heard fiberglass isnt completely waterproof anyways. On my next few top coats ill pay extra attention to bubbles. I was honestly scared ****less about fiberglassing but it went very well for me. Use epoxy with an hour working time, use cloth not mat, pre cut your pieces. Buy proper rollers and take your time mixing the resin.
 
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dingodan

Jack Dempsey
MFK Member
May 11, 2014
76
70
36
vancouver bc
Did my first topcoat last night and i would agree its near impossible to not get thousands of tiny surface bubbles. I found lightly brushing it after rolling it on did help alot. Im assuming that after several coats with light sanding between each coat this wont be an issue but i really dont know
 

dingodan

Jack Dempsey
MFK Member
May 11, 2014
76
70
36
vancouver bc
why did you decide to go the stacked 2x4 vs virt. 2x4?
looking great!
Its just how it was done in the plans i was following. Apparently it prevents the corners from being able to blow out which is ussually a weak spot. Doubt id do it that way again but its done now and itll help me sleep at night
 
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Devaji108

Feeder Fish
MFK Member
Apr 8, 2020
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Its just how it was done in the plans i was following. Apparently it prevents the corners from being able to blow out which is ussually a weak spot. Doubt id do it that way again but its done now and itll help me sleep at night
yeah 900 gal of water on the floor is no joke. better be safe than sorry!
if you where to do it again how would you do it now?
 

dingodan

Jack Dempsey
MFK Member
May 11, 2014
76
70
36
vancouver bc
yeah 900 gal of water on the floor is no joke. better be safe than sorry!
if you where to do it again how would you do it now?
Well i think i would just do a 3/4 plywood skeleton no 2x4 and fiberglassed the **** out of it inside and outside. In my experience the fiberglass was pretty easy and im sensitized to epoxy. Meaning i cannot get it on my skin AT ALL. Theres too many unknowns with the different expansion rates of wood and epoxy. So just build it like a high quality boat and i think thats the safest method. I am happy with the way i did it, but it was very time consuming so that being said i think one might as well go full fiberglass.
 
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nbrin

Feeder Fish
Apr 19, 2020
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Well i think i would just do a 3/4 plywood skeleton no 2x4 and fiberglassed the **** out of it inside and outside. In my experience the fiberglass was pretty easy and im sensitized to epoxy. Meaning i cannot get it on my skin AT ALL. Theres too many unknowns with the different expansion rates of wood and epoxy. So just build it like a high quality boat and i think thats the safest method. I am happy with the way i did it, but it was very time consuming so that being said i think one might as well go full fiberglass.
Was thinking of doing something like yours but slightly taller (62x31x40 inches). What thickness of plywood would you recommend so it does not bow (with a euro brace). In my case both of the larger sides will be mostly viewing panels. I thought of going full fibre but could not find the recommended thickness for my dimensions. What would you say would be an acceptable thickness? As for the fibre to avoid the bubbles it helps to first "soak" the plywood well (normally 2 to 3 coats of resin will do) otherwise you will have the air trapped between the fibre and the newly applied resin on top and the air will have to "fight" it way through the resin, which is why is ends up trapped. I found the best way is to soak the plywood, and when tacky apply the cloth with generous amounts of polyester resin with a normal roller and then press with an aluminium roller to remove the bubbles. Usually the finished product comes quite good. It is crucial but to always the next layer when tacky, otherwise, if it sets, you will have a cold joint. You can sand and apply again, but its not quite the same in terms of strength, as you will have multiple layers rather than one thick layer. You have to play with the hardener ratio to manipulate the setting times to get this, unless you plan to build it in shifts with someone else :)
 

dingodan

Jack Dempsey
MFK Member
May 11, 2014
76
70
36
vancouver bc
Ups has been "holding" my sweetwater epoxy for almost a month. Cant progress on the tank until i get it but heres the begining of my mechanical room/wall to keep me busy. The bottom pipes are the supply to my pumps and the top pipe installed is the output from my skimmer. More to come...

IMG_20200421_213714.jpg

IMG_20200421_214239.jpg
 
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dingodan

Jack Dempsey
MFK Member
May 11, 2014
76
70
36
vancouver bc
Was thinking of doing something like yours but slightly taller (62x31x40 inches). What thickness of plywood would you recommend so it does not bow (with a euro brace). In my case both of the larger sides will be mostly viewing panels. I thought of going full fibre but could not find the recommended thickness for my dimensions. What would you say would be an acceptable thickness? As for the fibre to avoid the bubbles it helps to first "soak" the plywood well (normally 2 to 3 coats of resin will do) otherwise you will have the air trapped between the fibre and the newly applied resin on top and the air will have to "fight" it way through the resin, which is why is ends up trapped. I found the best way is to soak the plywood, and when tacky apply the cloth with generous amounts of polyester resin with a normal roller and then press with an aluminium roller to remove the bubbles. Usually the finished product comes quite good. It is crucial but to always the next layer when tacky, otherwise, if it sets, you will have a cold joint. You can sand and apply again, but its not quite the same in terms of strength, as you will have multiple layers rather than one thick layer. You have to play with the hardener ratio to manipulate the setting times to get this, unless you plan to build it in shifts with someone else :)
Yea i sanded between each coat. I would have had to take a week off work and sleep to have 1 continuous layer of epoxy. I cannot give you any recommendation as to plywood thickness as this is my first time doing this and am no expert. I would guess 3/4 to 1" for that depth but try looking for other builds with similar depth to yours. You can also look into fiberglass plywood hot tubs for some ideas
 
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