AlexGs Basement Plywood Build 2 displays one system.

[AlexG]

Hey Alex, i know you’re getting bombarded with questions but i have one. Do you use an adhesive or caulking between the plywood edges? Or just bare with the screws holding the sides together? I’m making a plywood sump

There are only plywood edges in the corners on this build and the plywood is secured together with ceramic coated deck screws and tight bond wood glue. I will note that wood glue cleanup is essential on the inside of the tank where it is sealed as it will prevent the pond armor from absorbing into the plywood. The glue cleanup might require some sanding to remove it all. When I sealed the tank the corner edges of the plywood were coated in pond armor, then a layer of fiberglass was laid down followed by several more coats of pond armor. When the top euro brace was installed the two plywood surfaces being joined were both sealed in pond armor so I used a combination RTV 108 adhesive and stainless steal screws to seal that edge.

 

[Murica]

There are only plywood edges in the corners on this build and the plywood is secured together with ceramic coated deck screws and tight bond wood glue. I will note that wood glue cleanup is essential on the inside of the tank where it is sealed as it will prevent the pond armor from absorbing into the plywood. The glue cleanup might require some sanding to remove it all. When I sealed the tank the corner edges of the plywood were coated in pond armor, then a layer of fiberglass was laid down followed by several more coats of pond armor. When the top euro brace was installed the two plywood surfaces being joined were both sealed in pond armor so I used a combination RTV 108 adhesive and stainless steal screws to seal that edge.

Thanks! Very helpful

 

[AlexG]

Got another slow motion capture of the mantis shrimp striking. Amazing how fast they are and the precision they have during a strike.

 

[NautiTang]

Great build Alex! Keep up the good work. Your dedication and selfless additions to the hobby are inspiring. It was quite a haul to get through this thread though very thorough.
Did you look into a concrete build at all before building? I've done a few quick searches on hare and MFK trying to find the pros and cons of each (concrete vs plywood) with a rough cost estimate no luck so far.

 

[AlexG]

Great build Alex! Keep up the good work. Your dedication and selfless additions to the hobby are inspiring. It was quite a haul to get through this thread though very thorough.
Did you look into a concrete build at all before building? I've done a few quick searches on hare and MFK trying to find the pros and cons of each (concrete vs plywood) with a rough cost estimate no luck so far.

I have considered concrete or cinder blocks for a future builds. When I was building these tanks I needed to build something that I could do on my own without needing to hire anyone to help. I landed on plywood because its easy to work with and would hold up to the tank sizes that I wanted to build. While I did run into an issue with the 720 due to its depth it was corrected with bracing. The one issue that I had with concrete was to really do it right you need to do it in a single pour with re-rod and that means a visit from the cement company into a difficult to reach place to pour cement. It was just not practical for my current house and would have likely costed far more than the plywood tanks. The issue of removing the tanks when I move would also become an issue since it would require a concrete saw to remove them if the next home owner does not want them. I want to say that building my two tanks with the glass was ~6k. Based on the experience with my current tanks I have decided that next time I am going to a different building method with four glass sides and a wood/fiberglass bottom. My idea is to make a large tank that I can build rather quickly and have the ability to take down and put back up if I move. I would also like to make the new displays peninsulas to maximize viewing.

Here are some pros and cons that I have considered for my builds

• Plywood Tank
  • Pros
    • Easy to build with minimal help
    • proven method of building strong tanks
    • Can be moved in some cases
    • lighter weight construction
    • Easier to cut up if tear down is needed
    • Modifications are possible after initial construction
    • Easier to make repairs with lower cost materials
  • Cons
    • Takes time to properly build and cannot be done overnight
    • Limits to how tall the tank can be higher risks over 36" tall
    • Viewing can be limited
    • Structural failure if designed wrong
• Concrete Tank
  • Pros
    • Unmatched strength
    • proven method of building tanks
    • No limits to size you can go with proper engineering
    • super tall tanks possible
  • Cons
    • Risk of water intrusion into concrete if not sealed properly
    • Structural failure if designed wrong
    • Higher cost if cement company needs to be hired
    • Can't be moved once in place
    • Modifications can be difficult after construction is completed

 

[Sltloser]

Hi Alex,

I've been following along with your build for a little while, and I want to first say that your planning and construction has been inspirational! In your previous post you talk about aquariums over 36" have higher risks. What specifically are the risks associated with this? Is it getting the proper glass thickness, or constructing the aquarium to be strong enough to handle that much water volume?

A non related questions, what made you choose glass over acrylic? I've seen plywood aquariums built both ways and was wondering what your thoughts were?

Thank you for taking the time to answer these!

 

[NautiTang]

4 sided viewing plywood tank sounds pretty cool. I'm curious how you would do corner bracing though. Woukd you use 4x4s or 6x6s for the corners, steel frame could be cool you could keep the form a little smaller but you may have to have somone weld is up, or do you have something else in mind?
You may have answered this question at some point but how much ballpark did you spend on your skimmer? Induction tank, pvc parts, the 2 pumps etc.

 

[NautiTang]

if you remember the problem he had with the bowing of the back and side on the 720 thats what he's referring to. Pressure in a fluid builds with height (depth) not volume, so the deeper the tank the more forces are being exerted on the panels or panes of glass/ acrylic.

To answer the glass vs acrylic question you have the same pros and cons a fully glass or acrylic tank does with the addition of the fact that silicone does not bond with acrylic so if you choose acrylic your sealing method will have to be a bit more robust. With glass you can run a good bead to seal the glass to the wood and an additional around the edges with plywood that will seal it but you'll need something else to hold the pane in place (ie a flange and/or bolts)

Alex may have more insight and/or reasons for his choice. But I hope this answers you questions.

 

[Sltloser]

if you remember the problem he had with the bowing of the back and side on the 720 thats what he's referring to. Pressure in a fluid builds with height (depth) not volume, so the deeper the tank the more forces are being exerted on the panels or panes of glass/ acrylic.

To answer the glass vs acrylic question you have the same pros and cons a fully glass or acrylic tank does with the addition of the fact that silicone does not bond with acrylic so if you choose acrylic your sealing method will have to be a bit more robust. With glass you can run a good bead to seal the glass to the wood and an additional around the edges with plywood that will seal it but you'll need something else to hold the pane in place (ie a flange and/or bolts)

Alex may have more insight and/or reasons for his choice. But I hope this answers you questions.

Thank you for the information!

 

[NautiTang]

I'm no expert on any of this this is what I've gleaned from my own readings and such as I'm preping and planning my own future system, so there is very likely more good info or ways to do the acrylic than I mentioned, but I prefer the high clarity glass approach so I haven't dont much research on the acryilic. So if you prefer acrylic then I recommend more research on it

 

[AlexG]

Hi Alex,

I've been following along with your build for a little while, and I want to first say that your planning and construction has been inspirational! In your previous post you talk about aquariums over 36" have higher risks. What specifically are the risks associated with this? Is it getting the proper glass thickness, or constructing the aquarium to be strong enough to handle that much water volume?

A non related questions, what made you choose glass over acrylic? I've seen plywood aquariums built both ways and was wondering what your thoughts were?

Thank you for taking the time to answer these!

There were a few things that drove my decision to stay at 36" high as a max on my big tank as I originally wanted to go 48" tall. Water pressure becomes an issue the taller the tank is and much of my reading on MFK and around the internet on plywood tanks taught me that once you go past 36" tall the catastrophic failure rate went up. I even saw a few interviews or posts where builders had lowered water levels or even rebuilt tanks to reduce height/water pressure. Since I never built a plywood tank before I also was concerned that my lack of experience coupled with a 48" tall tank could be a disaster waiting to happen which was the first reason I went with a 36" height.

I wanted to use glass as I am not a fan of acrylic because it scratches so easily. I used to do a lot of aquarium maintenance for personal and business tanks and every acrylic tank I serviced was always a nightmare to deal with and scratches were a constant issue. I know that scratches can be removed but its a pain and I would rather have the ability to use a metal blade to remove coraline algae over a plastic blade any day. The issue of bonding acrylic to a plywood tank is also was a concern as the use of a pressure seal does work but there is little information on how to do it right. At the time I was researching the only glass I was aware of at the time that would work for a 48" tall tank was 1" glass and I could not even find it when i looked. I later found out that tempered 3/4" glass can be used for a 48" tall tank.

Between the higher risks of a taller tank, my lack of experience building plywood tanks, and the thought that I could not find the right kind of glass I decided to stick with 36" tall.

 

[Sltloser]

There were a few things that drove my decision to stay at 36" high as a max on my big tank as I originally wanted to go 48" tall. Water pressure becomes an issue the taller the tank is and much of my reading on MFK and around the internet on plywood tanks taught me that once you go past 36" tall the catastrophic failure rate went up. I even saw a few interviews or posts where builders had lowered water levels or even rebuilt tanks to reduce height/water pressure. Since I never built a plywood tank before I also was concerned that my lack of experience coupled with a 48" tall tank could be a disaster waiting to happen which was the first reason I went with a 36" height.

I wanted to use glass as I am not a fan of acrylic because it scratches so easily. I used to do a lot of aquarium maintenance for personal and business tanks and every acrylic tank I serviced was always a nightmare to deal with and scratches were a constant issue. I know that scratches can be removed but its a pain and I would rather have the ability to use a metal blade to remove coraline algae over a plastic blade any day. The issue of bonding acrylic to a plywood tank is also was a concern as the use of a pressure seal does work but there is little information on how to do it right. At the time I was researching the only glass I was aware of at the time that would work for a 48" tall tank was 1" glass and I could not even find it when i looked. I later found out that tempered 3/4" glass can be used for a 48" tall tank.

Between the higher risks of a taller tank, my lack of experience building plywood tanks, and the thought that I could not find the right kind of glass I decided to stick with 36" tall.

Thank you for all the good info! Now that you're more comfortable with plywood aquarium building do you think your next tank might be that deep? Or will you stick to 36"?

 

[AlexG]

4 sided viewing plywood tank sounds pretty cool. I'm curious how you would do corner bracing though. Woukd you use 4x4s or 6x6s for the corners, steel frame could be cool you could keep the form a little smaller but you may have to have somone weld is up, or do you have something else in mind?
You may have answered this question at some point but how much ballpark did you spend on your skimmer? Induction tank, pvc parts, the 2 pumps etc.

I am still working out details but the best way to think of this tank would be that its a hybrid. I would make a channel on the bottom of the plywood/fiberglass bottom of the tank wide enough for the glass to sit in with spacers installed. On the corners it would be glass on glass connection but a hollow 4"x4" Hardwood post would be in each corner to tie the bottom of the tank to the wood/metal top frame with threaded rods. On the top frame I would use PVC pipes to enclose threaded rods for cross braces as needed to tension the top frame. The hope is that it can all be dry fit together with spacers on the glass with the top frame and bottom tied together first. Then all I would need to do is inject RTV on all the seams let it cure and fill. Not sure if it will work out that way but I am thinking that I will make a prototype at some point to test out this design on a smaller scale.

The skimmer with everything needed to build it was ~$1000 which was a significant savings over the cost of a commercial skimmer in the $3000-$5000 price range. I will likely make another one of these skimmers for my next system. I learned a lot making this skimmer and will definitely gravity feed my next skimmers if I can to eliminate the need for even more pumps.

 

[NautiTang]

The gravity fed idea is pretty cool and probably a lot of savings to be had there too. As always thanks for the well worded answer!
On the topic of theoretical future tank; 1.) Would the hollow hardwood 4x4 be inside the glass seam or outside with perhaps a notch routed out of one of the corners to straddle the seam for support? 2.) Would you cut out a notch for that glass to sit in in the bottom plywood/fiberglass or build one with, for example strips of wood of whatever dimension (2x4) on either side of where the glass would sit?
I like talking and thinking about different construction methods and have gotten many good ideas from you, and I thank you again for your efforts to document your experiences, ideas, experiments and so forth on here. Its a true wealth of knowlege.

 

[AlexG]

The gravity fed idea is pretty cool and probably a lot of savings to be had there too. As always thanks for the well worded answer!
On the topic of theoretical future tank; 1.) Would the hollow hardwood 4x4 be inside the glass seam or outside with perhaps a notch routed out of one of the corners to straddle the seam for support? 2.) Would you cut out a notch for that glass to sit in in the bottom plywood/fiberglass or build one with, for example strips of wood of whatever dimension (2x4) on either side of where the glass would sit?
I like talking and thinking about different construction methods and have gotten many good ideas from you, and I thank you again for your efforts to document your experiences, ideas, experiments and so forth on here. Its a true wealth of knowlege.

Up to this point this idea has just been in my head but I decided to make a little drawing up to show what I am looking to do. I would make an over sized tank bottom of wood/fiberglass to accommodate corner support posts. I would also make a over sized top frame to tie into the bottom. I want to be able to gently sandwich the glass between the top and bottom frame to provide extra stability for the glass as I want to go with a 36" or 48" height.

 

[NautiTang]

Interesting idea, I've never seen anything like it.

 

[Devaji]

Up to this point this idea has just been in my head but I decided to make a little drawing up to show what I am looking to do. I would make an over sized tank bottom of wood/fiberglass to accommodate corner support posts. I would also make a over sized top frame to tie into the bottom. I want to be able to gently sandwich the glass between the top and bottom frame to provide extra stability for the glass as I want to go with a 36" or 48" height.

that is a cool idea. I was thinking of a plywood bottom tank as well then all glass. but with your idea one could go bigger! I love the idea on you going peninsula on your next tank I have a think for them. I have a nano and a res red 650.

I think I could go smaller peninsula tank as you have so much more viewing pleasure. that said you have to have a place for it the works. I even was looking at square tanks...
keep us posted.

 

[AlexG]

Interesting idea, I've never seen anything like it.

Thanks @NautiTang

Part of the reason I was thinking this route was the width and length of the tank as the bottom piece of glass would need to be really big and would require a custom size piece made which would be $$$$ and really hard to move. I think my next step will be to make a prototype scaled down to a more reasonable size. Maybe a frag tank or a divided mantis tank.

 

[AlexG]

that is a cool idea. I was thinking of a plywood bottom tank as well then all glass. but with your idea one could go bigger! I love the idea on you going peninsula on your next tank I have a think for them. I have a nano and a res red 650.

I think I could go smaller peninsula tank as you have so much more viewing pleasure. that said you have to have a place for it the works. I even was looking at square tanks...
keep us posted.

I was thinking that the large scale versions of these tanks would go into a new house. Not sure when I would be moving but I was thinking in the next few years I would like to get another house with a better basement layout. I do have enough room in my basement to build a full scale version but I think for now I would only build a prototype or a frag tank to test this method to see if it holds water.

 

[vikinglord13]

Sweet!
Alex, have you considered just siliconing 4 glass panels together for the side, then sealing them to the plywood again, then using support beams like 2x4s or 2x6s on your corners and bottom to help with the seal along the bottoms?

I'm just curious why use 4x4s at all when you could seal the panels together. Is this a cost decision for you where the larger glass panels cost so much more? I've never really looked into pricing on large panels of glass, I imagine just a few more inches at that size equals a few hundred bucks, easily!