Mountains of sawdust (360g plywood, LED, Arduino build)
- Thread starter der_wille_zur_macht
- Start date
der_wille_zur_macht
Team RC
Thanks. I hope so!
Yes, though it really depends on how you count costs. If you tried to get a custom maker to build this tank out of acrylic or glass (there's no such thing as a tank this size off-the-shelf), it would probably cost 4 - 5 times what this tank is costing me in materials.
If you bought glass or acrylic yourself to build the tank, it would probably cost 2 -3 times what this tank costs in materials.
Of course, those numbers are NOT including my labor. I'm guessing I'll have somewhere around 60 - 80 hours of labor in this tank. I was initially thinking 100 hours, but it's going faster than I expected. And I'm probably a slow worker - if you were familiar with these methods and very proficient in woodworking, you could probably whip this tank out in 40 hours.
And if you're trying to scale these numbers up or down to other tank sizes, I would roughly guess that below 150 - 200 gallons, the plywood tank isn't cheaper any more. Thinner and smaller glass/acrylic panels are pretty cheap, and as glass tanks get smaller, the costs per unit of tank size drop off quickly. Meanwhile, the plywood/epoxy construction this tank is made out of doesn't really get any cheaper per unit of size as you go smaller. Plywood is probably cheapest from around 200 gallons up to a few thousand gallons or so, after which point you'd probably be thinking about concrete.
phobos2deimos
New member
I'm digging it so far. Looking forward to more!
How thick is the plywood? Sorry if you stated it earlier. Hard to tell from the pics.
How thick is the plywood? Sorry if you stated it earlier. Hard to tell from the pics.
der_wille_zur_macht
Team RC
It's 3/4" oak hardwood ply. Not sure what the inner plies are made of, but it's got an oak veneer on it. Honestly if I was to do it again, I'd get it without the oak veneer. It's not going to add anything visually (tank will be painted on the inside and behind drywall on the outside) and any glues/sealers/etc. I apply have to penetrate the veneer to get to the wood beneath.
der_wille_zur_macht
Team RC
A question in case the other ply builders are reading this thread. How do you all feel about bulkheads in the bottoms of ply tanks?
I'll be doing the overflow through the "end" near the bathroom, and return over that side of the tank. I was originally planning on powerheads for circulation, but stugray's recent VFD thread has me hooked.
So, I need to get a closed loop on this tank. I'll need a 2" bulkhead for the inlet, and several 1.5" for returns back to the tank. I'd like to hide all of this behind or under rockwork. Thanks to the peninsula orientation, the bathroom wall is the only wall I can do plumbing through, and since rockwork will be sparse, I won't be able to hide enough bulkheads in that wall.
Which leaves me with lots (4 - 5 at least) of big bulkheads through the bottom of the tank. I'd use heavy bulkheads for sure, but I'm still nervous about drilling the bottom of the tank. Thoughts anyone?
I'll be doing the overflow through the "end" near the bathroom, and return over that side of the tank. I was originally planning on powerheads for circulation, but stugray's recent VFD thread has me hooked.
So, I need to get a closed loop on this tank. I'll need a 2" bulkhead for the inlet, and several 1.5" for returns back to the tank. I'd like to hide all of this behind or under rockwork. Thanks to the peninsula orientation, the bathroom wall is the only wall I can do plumbing through, and since rockwork will be sparse, I won't be able to hide enough bulkheads in that wall.
Which leaves me with lots (4 - 5 at least) of big bulkheads through the bottom of the tank. I'd use heavy bulkheads for sure, but I'm still nervous about drilling the bottom of the tank. Thoughts anyone?
der_wille_zur_macht
Team RC
Nice work Steve. Gives me confidence to try myself. Though my forms probably won't be as cool as yours. 
iwishtofish
Active member
This is fascinating to follow!
This may sound like a stupid question, but is there going to be any interior coating of the plywood other than veneer? Perhaps fiberglass, or something like that? Will the integrity of the tank come mainly from the methods used to join the plywood at the edges?
This may sound like a stupid question, but is there going to be any interior coating of the plywood other than veneer? Perhaps fiberglass, or something like that? Will the integrity of the tank come mainly from the methods used to join the plywood at the edges?
der_wille_zur_macht
Team RC
That's what I was thinking.
Once the wood structure is finished, I'll coat the inside with epoxy. We're not talking a simple brushed-on application here, but rather a cast (poured) 1/8" - 3/16" thick layer of epoxy. This should be sufficient to provide waterproofing AND act as a durable finish inside the tank. The wood structure is essentially a substrate for this epoxy coat.
I have some composites experience in other areas (boats and airplanes) where you'd typically use fiberglass or other material to build up the composite, but in this case the wood box is stiff enough. Pouring a big thick layer of epoxy is kind of a brute force method vs. doing a nice delicate layup of cloth, but it's definitely proven to work, so I'm not worried. Several other folks in my immediate geographical area have built tanks like this from 400 - 1,000g in size and it's turned out fine.
InfernoST
Member
So far it looks awesome but I have 2 questions. 1st - Wouldn't it be wise to layup some cloth in the corners only 1st then epoxy the entire inside of the tank? 2nd - Since this tank is going on the 1st fl and you have a basement has the strength of the floor been taken into consideration since you will plopping down a few thousand pounds it?
Barra-aquariums
New member
hi, interesting work, keep posting..
der_wille_zur_macht
Team RC
Glass. Many locals have built plywood tanks this size (or even larger) with "half inch" glass. So whatever the real size is closest to that (15mm? 17mm? something like that.)
Gimmie 10 minutes.
I have some photos from this morning. But, it's the holidays. Progress has been slow.Question 1: The corners are probably the strongest parts of the tank as-is. Still, for reinforcement, I'll be doing a nice fat fillet. Some people doing this style of tank have put lumber triangles in the corners, but I'm not too fond of that idea. An epoxy fillet should be easier, and stronger.
I will be going in to some detail about structural reinforcements in a few weeks when I'm at that point in the project. I will be doing some reinforcement, but it's probably not strictly required, since the tank will be directly over two MASSIVE beams (this is a 200 year old post-and-beam house.)
29reef
It's all about the flow
Great build, I only have my doubts about using a hrv to heat the tank. I would think some sort of heat pump with a ground loop or standard outdoor unit(with indoor coil) would be best. If you used your existing fau, it would have to be on to heat the tank. Unless it's winter I wouldn't think you use it much(so turning it on to use it's exaust would be a waste). Maybe build an indoor heat pump and use the hot/cold air for your home or just exaust it if the hot or cool air isn't needed. This method would use up a lot of power tho so I'm pretty sure that's why you've overlooked it. I'm sure it's not in code as well. I like how you've added a little different method to viewing the tank; personally I'd make the other two viewing panels larger but I'm sure it will work fine as is.
Last edited:
der_wille_zur_macht
Team RC
Sorry, did I say something about special effects at one point?
Wait for it. . . wait for it. . .
Yeah, the heat recovery thing is a bit of a pipe dream. Though, it's in the teens outside right now, a foot or two of snow on the ground, and the heat is on at least 7 months a year, so it's a good environment to do something like that. I'd definitely include some kind of logic so that it only used the heat recovery implementation when the furnace was on anyways.
Pics soon. . .
