Considering DIY Plywood tank

ReefsandGeeks · 07/16/2018, 09:09 AM

I've been considering upgrading to a large tank for quite some time now, and am now in the early stages of sorting out what direction I'd like to go. I've always imagined wanting a 210g DD tank, but any tank this size is costly new, and finding one with deep dimensions is tough. I've been keeping my eye out for deals on used tanks, but not many in the size I want come up in my area.

A couple of things got me wondering if I should just build my own tank, and I saw plywood tanks on here that actually look very nice. The nice thing about the plywood is they are exactly the size you want, and cheaper than a standard glass tank, at least at larger sizes. I'm pretty handy, and would be confident I could do it with some support on how to build them properly.

Another idea I had that would reduce the main cost of a DIY plywood tank, would be the glass. From what I've read, the glass peices are by far the most expensive part of the build. What I though here is a bit different, but what if you bought a large used tank and disassembled it to use the glass for the plywood tank? The though for this is I recently came across a 180 gallon tank that was being given away for free because it was leaking. I missed the opportunity to grab it because I am too afraid to try to take a large tank apart and re-silicone everything and leave it in my house. But I think if I came across something like that again, maybe I can use the glass sheets from it, and use them as viewing windows on a custom plywood tank. The best part would be I can make the tank as deep as I want, front to back, and not need to have a used tank the full size of the tank I'd build. Heck, with a 180g, I could even build a square tank with 2 viewing sides both 6' long, giving a tank around 580 gallons (at 26" height) if I really wanted, as long as I didn't want all sides to be viewing sides.

Anyone see any good reason a used tank couldn't be re purposed and it's glass used in a newly build plywood tank? Assuming of course the glass isn't all scratched up or damaged. I feel like this would make building a large plywood tank more affordable and able to be done much sooner than waiting to be able to afford a more traditional all glass tank. I'd also plan on some DIY equipment like a big protein skimmer also to help save on some money for such a large tank. DIY rock with cement...lots of ways to make a large tank relatively affordable. Plus would be a fun project for a long time with so much to do. I could see it being very rewarding doing essentially everything myself from the tank to the equipment to the rock work.

If everything is going to work out, I'll just have to decide where I can actually put a large tank so I can size it appropriately. Then if/when I decide to go for it, I'd be able to start my first build thread

mcgyvr · 07/16/2018, 09:23 AM

IMO plywood tanks are only cheaper when you don't value your time..

DougSupreme just did a 225g build here (just below your post right now).. Notice that his had leaks,etc... which took even more time I'm sure..

DougSupreme · 07/16/2018, 04:56 PM

Quote:

Originally Posted by mcgyvr

IMO plywood tanks are only cheaper when you don't value your time..

DougSupreme just did a 225g build here (just below your post right now).. Notice that his had leaks,etc... which took even more time I'm sure..

Its true, but there is a great deal of satisfaction in "doing it yourself"

Could I have done it cheaper if I counted my time. Most likely. I just feel good saying "Look what I can do...."

YMMV

Sent from my SM-G930V using Tapatalk

DougSupreme · 07/16/2018, 04:58 PM

Actually, the cost of the tank, stand, pumps, and plumbing hasn't reached the cost of a tank the same size. Not considering time, obviously, but it's still reasonable. The bigger the tank, the more DIY is cost effective

Sent from my SM-G930V using Tapatalk

Fishbulb2 · 07/16/2018, 07:28 PM

My thoughts is that I would love to do a 300G tank in my basement, but there would be no way to move an assembled tank down there. My thought would be a plywood tank might be easier to "assemble" in place.

Is that reasonable?
FB

mcgyvr · 07/17/2018, 05:04 AM

Quote:

Originally Posted by Fishbulb2

My thoughts is that I would love to do a 300G tank in my basement, but there would be no way to move an assembled tank down there. My thought would be a plywood tank might be easier to "assemble" in place.

Is that reasonable?
FB

It is a valid thought that if you want a tank larger than the doorways,etc.. to access said area that building the tank in the desired area is a good idea.

Its most certainly better to make that discovery before and not after the tank is sitting outside the basement with 5 of your buddies laughing at you for not thinking about tit first..

BigDave · 07/17/2018, 06:51 AM

You should never value time on any DIY project.

Time gets cancelled by experience/knowledge learned.

Just look at the cost of college these days.

mcgyvr · 07/17/2018, 08:21 AM

Quote:

Originally Posted by BigDave

You should never value time on any DIY project.

Time gets cancelled by experience/knowledge learned.

Just look at the cost of college these days.

Everyone is entitled to their opinion..

When the stated driving factor for going DIY is saving money then its only right to mention the cost of time..

ReefsandGeeks · 07/17/2018, 08:37 AM

I tend to agree not to value my time too highly with DIY projects. It would be different if the cost came out nearly the same as a store bought all glass tank, but being able to save money, and also have the control to make it the exact dimensions I'd want, with over flow how I want...etc and still come in at a lower cost of materials does make it an exciting project. Sure, it's a project that will take alot of time and if someone else was building it for me I'd expect to pay more than an off the shelf tank. I try not to take my time into consideration for cost purposes though unless it's something I'm trying to do for a profit.

I do also like the feeling of having done something by myself. I recently refinished my hardwood floors by myself and took them from splintered stained ugly wood to nice finished wood in a trendy dark grey. Transformed the whole look of the house and that particular project came out 80% cheaper than if I hired someone and paid for their time. Plus I have the satisfaction of having done it myself. That said, I think it will be quite some time before I want to do it again. I think doing 1 plywood tank would be fun, but doing several would lose it's fun value and would then be better to just buy an off the shelf tank if it's affordable.

Anyways, I'd personally look at the total actual material cost comparison between an off the shelf tank and the supplies needed for a DIY plywood one and make a desision based on that. If the costs are similar, I may just do off the shelf since I have a 1 year old and don't have alot of time for my projects. If there's a significant cost savings, than I can just let it be a long term project that gets worked on when I have time and eventually have a nice large tank. The tough part is knowing the costs of a DIY tank upfront.

ReefsandGeeks · 07/17/2018, 08:41 AM

Not trying to say time shouldn't be valued, but if it's something you would enjoy doing, than I feel you don't have to value your time as highly because the experience itself is enjoyable. If building a tank is going to feel like work and not something enjoyable, than time is a bigger factor and savings would have to be much more significant to justify the effort.

Each person values their time differently. If someone asked me to help them work on their car, I'd typically help for free because I enjoy working on cars and I'm not burn out on it as I don't do it for a living. But if someone asked me to help clean their house, I'd be more reluctant to help without getting something in return, even if it took the same amount of time.

ReefsandGeeks · 07/17/2018, 08:43 AM

All of this being said, is there anywhere I can get a very rough estimate of cost for a plywood tank based off of size? I'm not set right now on a particular footprint, so I think I'd be able to save more money on glass panels by re-purposing a used all glass tank, perhaps one that leaks and is very cheap. If that's a significant cost savings vs buying a new large sheet of glass, than that may make the project even more economical.

BigDave · 07/17/2018, 08:47 AM

Quote:

Originally Posted by mcgyvr

Everyone is entitled to their opinion..

When the stated driving factor for going DIY is saving money then its only right to mention the cost of time..

Sure, but how many people sit in front of a computer/tablet/tv for 1-2 hours each night that they could otherwise be working on a DIY project?

Waste time doing one thing or waste time doing something else. You can't justify time=money for projects done outside of work hours.

Now... if you took 5 days of PTO to build something, then you can put a cost to it. Or if that project is keeping you from making money in some other fashion.

Otherwise, it's a hobby. The time spent building a tank, or cleaning it afterwards is hobby-time. Not money-making time.

mcgyvr · 07/17/2018, 10:05 AM

To me....ALL time has value..
And all time should be valued..

And yes.. Experience or gaining experience also carries value..
One must weigh examine all the costs..

My initial statement was only to imply that if you aren't valuing your time input into a project then you might want to include that to compare apples/apples..
The cost of an off the shelf aquarium isn't bad at all when time is factored in.

ReefsandGeeks · 07/17/2018, 11:33 AM

I did have a different outlook on money when I worked hourly jobs, but since moving to a salaried position, my views have changed some. I used to be able to work more when I wanted to splurge and buy something I could just work a more hours at what I was good at and buy what i wanted. But now, I can't do that. So having a very set budget, If I can't afford to buy off the shelf what I want, but can put in alot of work to get something cheaper that I can, than That may e the only option i have other than saving a long time.

Again, to each his own. All time has value, but time wasted having fun isn't time wasted at all. Personally, I like taking on these type of projects. But if it ended up being identical cost either way (time not factored in) than I'd just buy off the shelf and take on another project that would double as a money saver or something. So thinking about it like that, I do value my time because cost not being a factor at all, I'd get the all glass off the shelf tank. But for even fairly modest savings, I may consider DIY because it is fun to build.

Anyone else ever build something they needed or wanted just because they could? If you're into cars you can probably relate this to built "souped up" cars vs. bought "stock super cars". Sure, I can build a car that will be faster than a ferrari for half the price, but if both were presented to me by someone else, I'd take the ferarri every time. But when my own money is being spent, it's hard to justify the cost at times for the convinience of something being done for you. Very dependant on the situation.

Anyways, back to the purpose of this thread...Other than time and cost, what's the pros or cons of building a plywood tank vs buying a traditional tank? Are plywood tanks reliable? quieter? better insulation? easier/harder to clean?...etc.

BigDave · 07/17/2018, 11:51 AM

Quote:

Originally Posted by devastator007

Anyways, back to the purpose of this thread...Other than time and cost, what's the pros or cons of building a plywood tank vs buying a traditional tank? Are plywood tanks reliable? quieter? better insulation? easier/harder to clean?...etc.

This is going to sound unrelated, but I think it applies...

My dad and I built a plywood boat when I was in Jr High. People have been building wooden boats for years. A well built wooden tank should last as long as any all-glass one. If anything, I might even argue a wooden tank is more structurally sound because you can embed screws and other joinery techniques into the corners whereas all-glass is relying on the silicone to hold it all together.

While wood itself doesn't hold up well to moisture, it's really just a medium to give the fiberglass structure. The Fiberglass and epoxy do all the sealing.

I'd start with a smaller project. Build a box that's closer to the size of a 20-30 gallon tank and see what all it takes to seal it. See how much effort it takes and decide from there.

Do you have any woodworking experience already? If not, then there's a learning curve with that too. Edges need to be straight. Joints need to be tight.

oreo57 · 07/19/2018, 11:00 PM

Quote:

Originally Posted by mcgyvr

To me....ALL time has value..
And all time should be valued..

And yes.. Experience or gaining experience also carries value..
One must weigh examine all the costs..

My initial statement was only to imply that if you aren't valuing your time input into a project then you might want to include that to compare apples/apples..
The cost of an off the shelf aquarium isn't bad at all when time is factored in.

I get your point, but do you send yourself a bill for every clean/feed/water change???

If one valued time that way, unless you are selling what you are raising it's wasted time..

OF course that all depends on level of success as well..

It's more philosophy than fact..

In my mind the only time it really applies is in commercial endeavors..
Example:
How long to remodel and how much rent would one lose in the mean time..
But to be honest, even then, mostly came out ahead..but not always.

paphater · 07/21/2018, 10:27 PM

Having built my acrylic tank, and planning a new plywood build next year, it's really only worth it financially if it's big and has uncommon dimensions. My plywood will be a 10' 300 gallon and acrylic gets crazy expensive past 8'. You'll also need to factor in whatever tools you may need to buy, which is only a bad thing if you never plan using them again.

And time is really only a concern if you are in a hurry. I built my acrylic over 3 months when I had time. Built my stand in a day my center support was off an inch so I had to use a 20 gallon long on a 200 gallon tank for six months

der_wille_zur_macht · 07/26/2018, 11:31 AM

Quote:

Originally Posted by devastator007

All of this being said, is there anywhere I can get a very rough estimate of cost for a plywood tank based off of size?

Probably not but you can get a good idea looking at build threads on here. I did a 360g plywood tank several years ago and the tank itself was probably about $100 in wood, $250 in glass, $200 in epoxy, and maybe $100 in other consumables and supplies. A comparable custom glass or acrylic tank would have probably been $3k or so.

Glass panels can be expensive but you need to shop. I had estimates that were all over the map. The most expensive estimate was more than twice what the cheapest was. Plus you can modify your design to reduce the number and size of panels if you're that concerned about cost - I had three panels, if I'd done only one the glass cost would not have been the biggest line item.

Quote:

Originally Posted by devastator007

Anyways, back to the purpose of this thread...Other than time and cost, what's the pros or cons of building a plywood tank vs buying a traditional tank? Are plywood tanks reliable? quieter? better insulation? easier/harder to clean?...etc.

It's really hard to speak to criteria for deciding on off the shelf vs DIY. It's a very personal decision and if you try to turn it into a math problem or something totally quantifiable, you'll probably be unsatisfied. You have to do it because you want to do it.

There's a strong argument for flexibility in that DIY means you get your exact requirements met.

The only true advantage that can't be argued is the fact that DIY means you did it yourself. That can be very rewarding. The flip side of that advantage is, if there's a problem, you've got no one to support you.

d-man · 07/27/2018, 05:14 PM

I’m going to be starting my plywood 960g(8’x4’x4’) in mid August. It’ll be my 3rd one but this will be slightly different and more time as I have to build it in its location. Which is a bit worrisome cuz that also means I need to leak test it in its location...the dining room wall/laundry room. Obviously it will no longer be a laundry room. There’s no windows or doors that will allow me to move it in through at that size. So logistically its a lil more of a pain in the @SS but so be it.

salty joe · 07/28/2018, 07:59 PM

I built a 4'x8'x3' plywood tank a few years ago. I screwed and glued two pieces of 3/4" plywood together and made the box with 1 1/2" thick panels. The 4' sides didn't need any additional support. The 1 1/2" thick bottom of the coast to coast exterior overflow box provide excellent stiffness on the back panel. I screwed and epoxied a piece of 3"x4"x1/4" angle iron to the top front. I get about 1/16" bow at the back panel and about 1/8" bow at the front panel, well within the safe range, IMO. I used two coats of epoxy and the pour method using a torch to pop bubbles after each pour. I have close to 1/4" epoxy and it is tough stuff!
Bottom line, you need a really sturdy box to start with. Also, pour the top edges at the same time you pour the bottom. All this assumes not using fiberglass and the wood box is the extent of the structural integrity. I worked with fiberglass one time and swore off (at) it.
Also, if you're gonna build a big plywood tank, buy a gallon of Titebond glue from the getgo, at least if you plan on laminating plywood. Don't underestimate how hard it is to roll a big tank over for the pours. I couldn't do it by myself.

I consider the time I spent building this big tank very well spent. (:

07/16/2018, 09:09 AM	#1
ReefsandGeeks Registered Member Join Date: Sep 2014 Location: Pittsburgh, PA Posts: 1,708	Considering DIY Plywood tank I've been considering upgrading to a large tank for quite some time now, and am now in the early stages of sorting out what direction I'd like to go. I've always imagined wanting a 210g DD tank, but any tank this size is costly new, and finding one with deep dimensions is tough. I've been keeping my eye out for deals on used tanks, but not many in the size I want come up in my area. A couple of things got me wondering if I should just build my own tank, and I saw plywood tanks on here that actually look very nice. The nice thing about the plywood is they are exactly the size you want, and cheaper than a standard glass tank, at least at larger sizes. I'm pretty handy, and would be confident I could do it with some support on how to build them properly. Another idea I had that would reduce the main cost of a DIY plywood tank, would be the glass. From what I've read, the glass peices are by far the most expensive part of the build. What I though here is a bit different, but what if you bought a large used tank and disassembled it to use the glass for the plywood tank? The though for this is I recently came across a 180 gallon tank that was being given away for free because it was leaking. I missed the opportunity to grab it because I am too afraid to try to take a large tank apart and re-silicone everything and leave it in my house. But I think if I came across something like that again, maybe I can use the glass sheets from it, and use them as viewing windows on a custom plywood tank. The best part would be I can make the tank as deep as I want, front to back, and not need to have a used tank the full size of the tank I'd build. Heck, with a 180g, I could even build a square tank with 2 viewing sides both 6' long, giving a tank around 580 gallons (at 26" height) if I really wanted, as long as I didn't want all sides to be viewing sides. Anyone see any good reason a used tank couldn't be re purposed and it's glass used in a newly build plywood tank? Assuming of course the glass isn't all scratched up or damaged. I feel like this would make building a large plywood tank more affordable and able to be done much sooner than waiting to be able to afford a more traditional all glass tank. I'd also plan on some DIY equipment like a big protein skimmer also to help save on some money for such a large tank. DIY rock with cement...lots of ways to make a large tank relatively affordable. Plus would be a fun project for a long time with so much to do. I could see it being very rewarding doing essentially everything myself from the tank to the equipment to the rock work. If everything is going to work out, I'll just have to decide where I can actually put a large tank so I can size it appropriately. Then if/when I decide to go for it, I'd be able to start my first build thread

07/16/2018, 09:23 AM	#2
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	IMO plywood tanks are only cheaper when you don't value your time.. DougSupreme just did a 225g build here (just below your post right now).. Notice that his had leaks,etc... which took even more time I'm sure.. __________________ Who me?

07/16/2018, 04:58 PM	#4
DougSupreme Registered Member Join Date: Oct 2003 Location: Illinois Posts: 1,226	Actually, the cost of the tank, stand, pumps, and plumbing hasn't reached the cost of a tank the same size. Not considering time, obviously, but it's still reasonable. The bigger the tank, the more DIY is cost effective Sent from my SM-G930V using Tapatalk __________________ Intelligence is knowing that a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad Current Tank Info: 75g mixed reef Last edited by DougSupreme; 07/16/2018 at 05:04 PM.

07/16/2018, 07:28 PM	#5
Fishbulb2 Registered Member Join Date: Mar 2006 Location: Bethesda, MD Posts: 1,807	My thoughts is that I would love to do a 300G tank in my basement, but there would be no way to move an assembled tank down there. My thought would be a plywood tank might be easier to "assemble" in place. Is that reasonable? FB __________________ Just getting back in, but trying to do it right! Current Tank Info: 40 gallon tank. SPS, LPS, few softies

07/17/2018, 10:05 AM	#13
mcgyvr Registered Member Join Date: Sep 2003 Location: North Carolina Posts: 20,050	To me....ALL time has value.. And all time should be valued.. And yes.. Experience or gaining experience also carries value.. One must weigh examine all the costs.. My initial statement was only to imply that if you aren't valuing your time input into a project then you might want to include that to compare apples/apples.. The cost of an off the shelf aquarium isn't bad at all when time is factored in. __________________ Who me?

07/17/2018, 06:51 AM	#7
BigDave Registered Member Join Date: Jul 2002 Location: Wylie, TX Posts: 473	You should never value time on any DIY project. Time gets cancelled by experience/knowledge learned. Just look at the cost of college these days.

07/17/2018, 08:37 AM	#9
ReefsandGeeks Registered Member Join Date: Sep 2014 Location: Pittsburgh, PA Posts: 1,708	I tend to agree not to value my time too highly with DIY projects. It would be different if the cost came out nearly the same as a store bought all glass tank, but being able to save money, and also have the control to make it the exact dimensions I'd want, with over flow how I want...etc and still come in at a lower cost of materials does make it an exciting project. Sure, it's a project that will take alot of time and if someone else was building it for me I'd expect to pay more than an off the shelf tank. I try not to take my time into consideration for cost purposes though unless it's something I'm trying to do for a profit. I do also like the feeling of having done something by myself. I recently refinished my hardwood floors by myself and took them from splintered stained ugly wood to nice finished wood in a trendy dark grey. Transformed the whole look of the house and that particular project came out 80% cheaper than if I hired someone and paid for their time. Plus I have the satisfaction of having done it myself. That said, I think it will be quite some time before I want to do it again. I think doing 1 plywood tank would be fun, but doing several would lose it's fun value and would then be better to just buy an off the shelf tank if it's affordable. Anyways, I'd personally look at the total actual material cost comparison between an off the shelf tank and the supplies needed for a DIY plywood one and make a desision based on that. If the costs are similar, I may just do off the shelf since I have a 1 year old and don't have alot of time for my projects. If there's a significant cost savings, than I can just let it be a long term project that gets worked on when I have time and eventually have a nice large tank. The tough part is knowing the costs of a DIY tank upfront.

07/17/2018, 08:41 AM	#10
ReefsandGeeks Registered Member Join Date: Sep 2014 Location: Pittsburgh, PA Posts: 1,708	Not trying to say time shouldn't be valued, but if it's something you would enjoy doing, than I feel you don't have to value your time as highly because the experience itself is enjoyable. If building a tank is going to feel like work and not something enjoyable, than time is a bigger factor and savings would have to be much more significant to justify the effort. Each person values their time differently. If someone asked me to help them work on their car, I'd typically help for free because I enjoy working on cars and I'm not burn out on it as I don't do it for a living. But if someone asked me to help clean their house, I'd be more reluctant to help without getting something in return, even if it took the same amount of time.

07/17/2018, 08:43 AM	#11
ReefsandGeeks Registered Member Join Date: Sep 2014 Location: Pittsburgh, PA Posts: 1,708	All of this being said, is there anywhere I can get a very rough estimate of cost for a plywood tank based off of size? I'm not set right now on a particular footprint, so I think I'd be able to save more money on glass panels by re-purposing a used all glass tank, perhaps one that leaks and is very cheap. If that's a significant cost savings vs buying a new large sheet of glass, than that may make the project even more economical.

07/17/2018, 11:33 AM	#14
ReefsandGeeks Registered Member Join Date: Sep 2014 Location: Pittsburgh, PA Posts: 1,708	I did have a different outlook on money when I worked hourly jobs, but since moving to a salaried position, my views have changed some. I used to be able to work more when I wanted to splurge and buy something I could just work a more hours at what I was good at and buy what i wanted. But now, I can't do that. So having a very set budget, If I can't afford to buy off the shelf what I want, but can put in alot of work to get something cheaper that I can, than That may e the only option i have other than saving a long time. Again, to each his own. All time has value, but time wasted having fun isn't time wasted at all. Personally, I like taking on these type of projects. But if it ended up being identical cost either way (time not factored in) than I'd just buy off the shelf and take on another project that would double as a money saver or something. So thinking about it like that, I do value my time because cost not being a factor at all, I'd get the all glass off the shelf tank. But for even fairly modest savings, I may consider DIY because it is fun to build. Anyone else ever build something they needed or wanted just because they could? If you're into cars you can probably relate this to built "souped up" cars vs. bought "stock super cars". Sure, I can build a car that will be faster than a ferrari for half the price, but if both were presented to me by someone else, I'd take the ferarri every time. But when my own money is being spent, it's hard to justify the cost at times for the convinience of something being done for you. Very dependant on the situation. Anyways, back to the purpose of this thread...Other than time and cost, what's the pros or cons of building a plywood tank vs buying a traditional tank? Are plywood tanks reliable? quieter? better insulation? easier/harder to clean?...etc.

07/21/2018, 10:27 PM	#17
paphater Registered Member Join Date: Feb 2016 Posts: 38	Having built my acrylic tank, and planning a new plywood build next year, it's really only worth it financially if it's big and has uncommon dimensions. My plywood will be a 10' 300 gallon and acrylic gets crazy expensive past 8'. You'll also need to factor in whatever tools you may need to buy, which is only a bad thing if you never plan using them again. And time is really only a concern if you are in a hurry. I built my acrylic over 3 months when I had time. Built my stand in a day my center support was off an inch so I had to use a 20 gallon long on a 200 gallon tank for six months

07/27/2018, 05:14 PM	#19
d-man Registered Member Join Date: Nov 2009 Location: San Diego, ca Posts: 2,732	I’m going to be starting my plywood 960g(8’x4’x4’) in mid August. It’ll be my 3rd one but this will be slightly different and more time as I have to build it in its location. Which is a bit worrisome cuz that also means I need to leak test it in its location...the dining room wall/laundry room. Obviously it will no longer be a laundry room. There’s no windows or doors that will allow me to move it in through at that size. So logistically its a lil more of a pain in the @SS but so be it.

07/28/2018, 07:59 PM	#20
salty joe Registered Member Join Date: Oct 2002 Location: medina, ohio Posts: 2,419	I built a 4'x8'x3' plywood tank a few years ago. I screwed and glued two pieces of 3/4" plywood together and made the box with 1 1/2" thick panels. The 4' sides didn't need any additional support. The 1 1/2" thick bottom of the coast to coast exterior overflow box provide excellent stiffness on the back panel. I screwed and epoxied a piece of 3"x4"x1/4" angle iron to the top front. I get about 1/16" bow at the back panel and about 1/8" bow at the front panel, well within the safe range, IMO. I used two coats of epoxy and the pour method using a torch to pop bubbles after each pour. I have close to 1/4" epoxy and it is tough stuff! Bottom line, you need a really sturdy box to start with. Also, pour the top edges at the same time you pour the bottom. All this assumes not using fiberglass and the wood box is the extent of the structural integrity. I worked with fiberglass one time and swore off (at) it. Also, if you're gonna build a big plywood tank, buy a gallon of Titebond glue from the getgo, at least if you plan on laminating plywood. Don't underestimate how hard it is to roll a big tank over for the pours. I couldn't do it by myself. I consider the time I spent building this big tank very well spent. (: __________________ Time to roll the dice.