Large plywood tank

[crusso1993]

Hi...
I am giving very serious consideration to building a larger-sized tank out of plywood with glass inserts. Minimally, the dimensions will be 96 x 24 x 30. Optimally, the dimensions will be 96 x 48 x 36 or 96 x 48 x 48. I already know that I will NOT be using plywood from any of the big box stores. Their "premium" hardwood plywood is far from premium and has a potential for disastrous results. Instead, I will be buying the hardwood plywood from a lumber supplier. I would prefer to use Baltic Birch but true Baltic Birch is only available in 5' x 5' sheets. Therefore, I'll have to go with an "alternate" Baltic Birch or a different hardwood plywood. Any experiences, input or suggestions are very welcomed!https://www.reef2reef.com/threads/synergy-custom-sumptacular-giveaway.479680/

 

[P-Dub]

Hi...
I am giving very serious consideration to building a larger-sized tank out of plywood with glass inserts. Minimally, the dimensions will be 96 x 24 x 30. Optimally, the dimensions will be 96 x 48 x 36 or 96 x 48 x 48. I already know that I will NOT be using plywood from any of the big box stores. Their "premium" hardwood plywood is far from premium and has a potential for disastrous results. Instead, I will be buying the hardwood plywood from a lumber supplier. I would prefer to use Baltic Birch but true Baltic Birch is only available in 5' x 5' sheets. Therefore, I'll have to go with an "alternate" Baltic Birch or a different hardwood plywood. Any experiences, input or suggestions are very welcomed!https://www.reef2reef.com/threads/synergy-custom-sumptacular-giveaway.479680/

At a minimum, you will need to use MARINE GRADE plywood and coat in epoxy. Additionally, I would glass the epoxy as well with fiberglass.

 

[Erica-Renee]

I see no reason why not to use 3/4 ply from say Home depot or lows for this. I WOULD NOT USE Marine Plywood as its not the best for surface bonding as its so FULL Of chemicals and Wet .

 

[P-Dub]

I see no reason why not to use 3/4 ply from say Home depot or lows for this. I WOULD NOT USE Marine Plywood as its not the best for surface bonding as its so FULL Of chemicals and Wet .

You are absolutely incorrect. There are no such chemicals. The standard grades of interior or, rather non-exterior graded plywood is the one full of chemicals. Do your research. Marine grade is specifically designed to have excellent surface bonding characteristics, particularly with epoxy and polyester resins. I used to have a yacht refinishing business, I think I would know.

 

[cracker]

Interesting. I have built large sumps but not a tank that large. I'd really like to see some structural plans. Will you use glass?Will there be a break down the center?

I " think" 4Ford was kicking this around it's here somewhere.

 

[Muttley000]

Following. I have done a 270 gallon sump and am waiting for a home addition to do my big tank to get the wife's laundry out of my basement. In my research I second that marine grade plywood is unnecessary in this application, however if it makes you feel better I don't see a problem with it. If you get water to the plywood it's game over anyway, and epoxy bonds more than well enough to standard grades of plywood. When I did my sump the 4x8 sheets of Baltic birch at menards I found to have no lamination issues or voids, however I am not sure that would ring true from batch to batch. Excited to see what you come up with.

 

[P-Dub]

Folks, marine grade plywood is designed to be able to handle moisture should it get wet so, not game over. You could use exterior grade construction ply which utilizes the same adhesives as marine grade ply, but, the construction graded exterior ply have voids and checks and far fewer layers. The marine grades have no voids or checks and have significantly more layers. Sure you can use construction grade exterior ply but how long do you want this to last and how important is the peace of mind worth to you? These are the questions you have to answer. I find that knowing I used the best materials with the greatest durability and chance of longevity is kind of important to me, particularly when we are housing a small ecosystem. Your call, do whatever you wish and see how it goes. I just like the idea of providing the best for my reef and the assurances it provides my home.

 

[crusso1993]

Interesting. I have built large sumps but not a tank that large. I'd really like to see some structural plans. Will you use glass?Will there be a break down the center?

I " think" 4Ford was kicking this around it's here somewhere.

I do not have structural plans. I will be using glass inserts for viewing.
I'm not sure I understand what you mean by a break down the center? Are you referring to bracing?

 

[crusso1993]

Folks, marine grade plywood is designed to be able to handle moisture should it get wet so, not game over. You could use exterior grade construction ply which utilizes the same adhesives as marine grade ply, but, the construction graded exterior ply have voids and checks and far fewer layers. The marine grades have no voids or checks and have significantly more layers. Sure you can use construction grade exterior ply but how long do you want this to last and how important is the peace of mind worth to you? These are the questions you have to answer. I find that knowing I used the best materials with the greatest durability and chance of longevity is kind of important to me, particularly when we are housing a small ecosystem. Your call, do whatever you wish and see how it goes. I just like the idea of providing the best for my reef and the assurances it provides my home.

I'm in agreement with what you said P-Dub. I will be looking into getting the most plys as possible without voids. Voids are the only thing that really scare me as they will ultimately cause a failure. I am also planning on using fiberglass reinforcement along all the seams.

 

[cracker]

A center piece of ply with 2 glass panels as apposed to one long piece of glass.

 

[crusso1993]

Ohhh... no, I'm am not planning on a break. Just one long panel.

A center piece of ply with 2 glass panels as apposed to one long piece of glass.

 

[Softhammer]

P-Dub has hit the nail on the head. I’m 1000% percent certain that the big cold molded multi million dollar sport fishing yachts are not made out of Home Depot plywood. These boats last a century potentially, longer. The plywood argument was over before it ended. If you have ever seen a boat part made from junk plywood, you wouldn’t considered it for a second and all it takes is a few drops of water- or not, this junk dry rots too.

 

[P-Dub]

I'm in agreement with what you said P-Dub. I will be looking into getting the most plys as possible without voids. Voids are the only thing that really scare me as they will ultimately cause a failure. I am also planning on using fiberglass reinforcement along all the seams.

Personally, I would glass the entire interior or at the very least coat the ply with resin with multiple coats before and after glassing the seams. Marine is the only ply that is relatively free of voids or checks and worth the extra expense. I would recommend 9-13 ply. Best of luck, do some research and keep us posted. You probably know this but research proper prep between coats and the types of resins to use for this application. There are bonding and finish resins...

 

[Muttley000]

Folks, marine grade plywood is designed to be able to handle moisture should it get wet so, not game over. You could use exterior grade construction ply which utilizes the same adhesives as marine grade ply, but, the construction graded exterior ply have voids and checks and far fewer layers. The marine grades have no voids or checks and have significantly more layers. Sure you can use construction grade exterior ply but how long do you want this to last and how important is the peace of mind worth to you? These are the questions you have to answer. I find that knowing I used the best materials with the greatest durability and chance of longevity is kind of important to me, particularly when we are housing a small ecosystem. Your call, do whatever you wish and see how it goes. I just like the idea of providing the best for my reef and the assurances it provides my home.

I understand that but the tank is still leaking, it doesn't matter if it doesn't delaminate in this condition. my opinion only of course, I enjoy the differing viewpoints!

 

[Softhammer]

That’s the whole point dude. It won’t leak if build like a boat. We have 1000s of yachts here in Florida that don’t leak.

 

[P-Dub]

Ohhh... no, I'm am not planning on a break. Just one long panel.

You will have to reinforce a length you are planning on. Some sort of cleating and bulkhead. It may not have to be a solid, one-piece bulkhead but you will need cross-sectional reinforcement or it will bow and stress your seams.

 

[P-Dub]

I understand that but the tank is still leaking, it doesn't matter if it doesn't delaminate in this condition. my opinion only of course, I enjoy the differing viewpoints!

I understand your point, however, you are missing the point that IF there is a leak, the marine grade ply will handle it the best and not suffer the same catastrophic failure a construction grade ply would under the same circumstances. With marine-grade, you will more likely be able to repair said leak, if one should occur, with confidence that the ply is not trashed. Additionally, using marine ply on a tank, properly engineered and constructed, will lower the likelihood of failures. That is what I believe we all want to do, mitigate the possibility of failure in this hobby.

 

[Muttley000]

I understand your point, however, you are missing the point that IF there is a leak, the marine grade ply will handle it the best and not suffer the same catastrophic failure a construction grade ply would under the same circumstances. With marine-grade, you will more likely be able to repair said leak, if one should occur, with confidence that the ply is not trashed. Additionally, using marine ply on a tank, properly engineered and constructed, will lower the likelihood of failures. That is what I believe we all want to do, mitigate the possibility of failure in this hobby.

That I can agree with. I still probably wouldn't choose that route for myself, but appreciate your thoughts and ability to explain your position without the veiled insult lol. I am a woodworker but certainly not a boat builder, that is a trade that always intrigued me.

@crusso1993 I'm sorry if I took your thread down a rabbit trail, how are you planning to seal the tank? Also how are you planning on plumbing/providing flow?

 

[P-Dub]

That I can agree with. I still probably wouldn't choose that route for myself, but appreciate your thoughts and ability to explain your position without the veiled insult lol. I am a woodworker but certainly not a boat builder, that is a trade that always intrigued me.

@crusso1993 I'm sorry if I took your thread down a rabbit trail, how are you planning to seal the tank? Also how are you planning on plumbing/providing flow?

Veiled and overt insults are the domain of that "other" centralized reef forum, I believe. I prefer the civility of R2R and why I am no longer a member of the "other" forum. I believe there was no derailment of the current thread by you. Healthy debate and sharing of ideas will benefit all and glean good information through research of opposing opinions.

 

[Erica-Renee]

I have to admit for some reason when i here people on here say Marine plywood My mind has a image of Treated Ground contact ply .Something i use occasionally for exterior projects . Not Actual Marine grade Finish plywood Something this is Generally not available in this area. I know they are Completely Different animals .
I do as well feel this is a much better place to discuss a topic then others.