Plywood Tank

road8514 · Oct 22, 2014

Hello all,

Looking for thoughts from people that have built plywood tanks. Was looking at using pondarmor for the sealant. I was wondering can I treat all the wood panels as if they where glass and use a sealant such as dow cornering 795 or am I better off fiberglassing the edges? I am looking to be in the 400-600gal range.

Thanks
Road

Daniel@R2R · Oct 23, 2014

:bump:

TheReefKeeper · Oct 23, 2014

I have built one back in 1993 and I just uses stainless screws and a leach free 2 part epoxy paint think If I remember it was a Devo Bar Rust 235 and that's all.

If you have taller sides to hold large volume of gallons I would coat the entire inside with Fiberglass then coat with Bar Rust to prevent The MEPK's and styrene in the Resin from leaching out into the water. Two thin coats would be better than one think coat of Bar Rust.

Also corner supports and top supports would be best. I would supported with strapping before coating on the outside and possibly the inside.

I would coat not just the inside but the outside too.

Remember to have all your holes cut DO NOT and I stress to not cut hols after coating as this would create a weak point. I would not trust bulkhead seals around fresh holes.

Place your glass or whatever you will use for viewing inside after one coat of bar Rust or if you chose to use fiberglass. I would adhere with an Epoxy Tube sealer to prevent shrinkage. Tape or mask off the glass sand the perimeter of your Plexiglass and coat with either strips of more glass then a strap of wood coated with bar rust epoxy after in place. I would finally coat again with more tube epoxy sealant and more bar rust.

On a side note I would also use an epoxy Resin if you do use glass as the shrinkage is a lot less and the chance of any sort of Leaching is cut out. A Poly or Vinyl ester resin's MEPK or Styreen may still leach even when coated with the Bar Rust not a chance I would take if your spending this kinda coin may as well do it right.

You may not need glass at all with enough coats of bar rust it's more for long term security. The tank above has no Glass and lasted 10+ years and was given to Marco Rock he may still have it LOL

Waters · Oct 23, 2014

Excuse my ignorance but what is the benefit of a wood tank? What are they used for?

TheReefKeeper · Oct 23, 2014

A few size you want dimensions you want and some think to save cash but I found out the hard way it's not a whole lot cheaper if any to do correctly and have it last for the life of a store bought one.

road8514 · Oct 23, 2014

I the purpose of the plywood tank is to save on cost but also be able to construct it in my basement where I would not be able to get a tank that size down the stairs. Has anyone used the ponarmor epoxy. From their website they look like they have a good product. I would be making this into a shark tank and I am thinking 18-20in tall. I could brace the top but I dont want to do to much as I am not sure if I will put a window in or just make it top down viewing. Any thoughts on painting the wood pieces independently and using dow cornering 795 and putting it together like a glass tank? Using screws as well but using the 795 to create the seal?

TheReefKeeper · Oct 23, 2014

Here is the MSD of the Dow

DOW CORNINGÂ® 795 SILICONE BUILDING SEALAN T, LIMESTONE, English (44 KB)

I'm not sure this ^ is your stuff it says water resistant not water proof so if you have a breach in the epoxy coating it would go bad rater quick meaning over time it may expand with moisture and fail.

I also see Alcohol which leads me to believe it has shrinkage not necessarily good for structural ridgidness or strength good for a sealer with no structural properties.

I would probably go with something like this below if you insist to build in pannels.

NEW Six10 Epoxy Adhesive

It's meant for the marine industry it's epoxy and will not suck up water if their is a breach the Dow is a sealant not as much for structural purposes if you want to assemble in place with pre painted panels my money would be on the Six10 honestly.

Honestly I wouldn't build it in pieces and trust even tho the Six10 says it has a

"Flexural Strength 11,320 (PSI)"

I feel the west stuff is a better choice they even mention it has "stitch and glue boat construction, fiberglass laminate repair and general marine bonding"

JMO as I work in the Composite industry and have used a lot of different stuff over the years.

Not sure I mentioned above the BarRust is food grade I may have confused the part# been some years but it does not leach chemicals so look for the food grade coating.

road8514 · Oct 23, 2014

Ok thanks for your thoughts. The dow 795 is what some aquariums have used and some of their larger tanks. Also the BarRust is not the correct number as it says not for potable water.

I would still use screws to screw the panels of wood together I would just use the 795 or Six10 to do the inner seal like you see in a glass aquarium.

Daniel@R2R · Oct 24, 2014

Here's a pretty cool build thread you could check out: https://www.reef2reef.com/forums/large-aquariums-180g/31440-redtop03s-360g-plywood-adventure.html

It's older, but cool build IMO.

Daniel@R2R · Oct 24, 2014

And another: https://www.reef2reef.com/forums/large-aquariums-180g/93635-560-gallon-plywood.html

fat-tony · Oct 25, 2014

The standard build in our area (fingerlakes) included the shell being built. Once that was done, each corner would be reinforced with a 2x2 cut diagonal the long way and screwed into the corner and gorilla glued into place to help create a little better seal. On some of the joints that were seams in the middle of the tank, fiberglass tape may have been used just to give a little more piece of mind. To apply the epoxy, it was always mixed and then poured into each flat surface in a couple layers. This would help create a good water-tight seam because the epoxy would bind to itself in each corner and more/less become one big shell of a piece once it all hardened.

If you needed holes for the front/sides, you used putty to make a dam to hold the epoxy in place until hardening or for your closed loop holes, return holes, you just used a hole saw through the wood and epoxy. When installing the glass, use little spacers around the glass and frame, that helps give room for the glass to make a good bead with the caulk and epoxy surface.

Seen this method work with no issue all the way to a 1000 gallon that even included a surge wave system that "flushed" every minute or so.....was only taken out of service when the guy moved a couple years later.