Help! Plywood tank seams leaking!

[Valum]

Advice needed I recently built this tank 90gallon plywood tank my seems appear to be leaking and capillary action is making it soak onto the wood

I've fibreglassed the seals and covered with pond paint, I've then used pond seal to try and stop the leak but this has failed

Please help I've had to put the fish in QT and corals in a box

 

[D4jack]

That sucks! You're probably going to have to build a new one. Good luck trying to find a fix.

 

[lavoisier]

Fixing a leak is notoriously difficult. My first fiberglass/plywood tank failed and I had to rebuild after numerous attempts to reseal.

 

[AlexG]

Hate to say it but once the plywood is soaked it will start to delaminate and loose all its strength so a rebuild is likely needed. How long was this tank running? Do you have pictures of the stand the tank was on? What kind of pond seal were you using and how many coats did you apply? Also do you have any pictures of the inside of the tank where the leak occurred?

 

[CMMorgan]

Sorry, mate, looks like a goner.

 

[piranhaman00]

Do you have full pictures? I cant really tell whats going on.

 

[Valum]

Only these pictures, running for 2 weeks woods mostly dried out now and there appears to be no separation between the layers stand is custom made and level with vertical supports absolutely no flex when standing in the tank

 

[Rjramos]

People compare pros and cons of glass vs. plexiglas tanks here all the time. In this day an age, is there any benefit to a DIY plywood tank?

 

[DaneGer21]

People compare pros and cons of glass vs. plexiglas tanks here all the time. In this day an age, is there any benefit to a DIY plywood tank?

I know ANY tank can fail, but man, these plywood tanks really make me nervous. Although most people put them in their garage or basements for two reasons, their usually large tanks and the space is ideal, and two, less chance of damage from a DIY project.

 

[Valum]

I know ANY tank can fail, but man, these plywood tanks really make me nervous. Although most people put them in their garage or basements for two reasons, their usually large tanks and the space is ideal, and two, less chance of damage from a DIY project.

I get that but even though the seems have failed there no actual drips the wood is like a sponge at first giving you time to fix, from my experience even when you have a significant leak it's normally s dribble I've had glass tanks fail and that's normally catastrophic in comparison

 

[Valum]

Ok since the only suggestions are to rebuild it here's the approach I am going to take, I used a dehumidifier after leaving it to dry for 5 days, wood is dry now no separation in the wood grains only wet panel was mainly the bottom panel,

1 - cut around the perimeter of the tank floor seam
2 - unscrew bottom panel and remove
3- remove all excess fibre glass ensuring no damage to pond paint
4 apply coating of silicone between mating joints
5 - rescrew panel and apply bitumen paint to stand and lower half of the tank (external) this will dry like rubber and if and further leaks happen will provide a barrier
6- reseal all seams with black marine grade silicone

Water test

I have an additional plyboard to put on top of the stand to give some more strength to the tank

I see no issues with this worst case scenario it doesn't fix it then I'll give up and make an acrylic tank or something and put this as a pond outside as it's not dripping water only very slight weap

I'll update this thread to give anyone in my situation a solution or stop them wasting there money

 

[AlexG]

Ok since the only suggestions are to rebuild it here's the approach I am going to take, I used a dehumidifier after leaving it to dry for 5 days, wood is dry now no separation in the wood grains only wet panel was mainly the bottom panel,

1 - cut around the perimeter of the tank floor seam
2 - unscrew bottom panel and remove
3- remove all excess fibre glass ensuring no damage to pond paint
4 apply coating of silicone between mating joints
5 - rescrew panel and apply bitumen paint to stand and lower half of the tank (external) this will dry like rubber and if and further leaks happen will provide a barrier
6- reseal all seams with black marine grade silicone

Water test

I have an additional plyboard to put on top of the stand to give some more strength to the tank

I see no issues with this worst case scenario it doesn't fix it then I'll give up and make an acrylic tank or something and put this as a pond outside as it's not dripping water only very slight weap

I'll update this thread to give anyone in my situation a solution or stop them wasting there money

The approach seems sound for a repair. My challenge with a failure like this is understanding its point of origin and why it happened. If you feel the plywood is not damaged then I can understand the decision to move forward. I would suggest taking lots of pictures along the way for your own record. I often find that documenting a build with pictures helps me take a look back years later at how I did something if I can't remember how or why I did something a certain way. Do you have the LxWxH dimensions of this tank you can share? It seems this is a rather tall tank and I am wondering if it is taller than 60cm.

 

[Valum]

Ok since the only suggestions are to rebuild it here's the approach I am going to take, I used a dehumidifier after leaving it to dry for 5 days, wood is dry now no separation in the wood grains only wet panel was mainly the bottom panel,

1 - cut around the perimeter of the tank floor seam
2 - unscrew bottom panel and remove
3- remove all excess fibre glass ensuring no damage to pond paint
4 apply coating of silicone between mating joints
5 - rescrew panel and apply bitumen paint to stand and lower half of the tank (external) this will dry like rubber and if and further leaks happen will provide a barrier
6- reseal all seams with black marine grade silicone

Water test

I have an additional plyboard to put on top of the stand to give some more strength to the tank

I see no issues with this worst case scenario it doesn't fix it then I'll give up and make an acrylic tank or something and put this as a pond outside as it's not dripping water only very slight weap

I'll update this thread to give anyone in my situation a solution or stop them wasting

The approach seems sound for a repair. My challenge with a failure like this is understanding its point of origin and why it happened. If you feel the plywood is not damaged then I can understand the decision to move forward. I would suggest taking lots of pictures along the way for your own record. I often find that documenting a build with pictures helps me take a look back years later at how I did something if I can't remember how or why I did something a certain way. Do you have the LxWxH dimensions of this tank you can share? It seems this is a rather tall tank and I am wondering if it is taller than 60cm.

Yes it's 94.5cmx50x 66cm

 

[Valum]

Ok since the only suggestions are to rebuild it here's the approach I am going to take, I used a dehumidifier after leaving it to dry for 5 days, wood is dry now no separation in the wood grains only wet panel was mainly the bottom panel,

1 - cut around the perimeter of the tank floor seam
2 - unscrew bottom panel and remove
3- remove all excess fibre glass ensuring no damage to pond paint
4 apply coating of silicone between mating joints
5 - rescrew panel and apply bitumen paint to stand and lower half of the tank (external) this will dry like rubber and if and further leaks happen will provide a barrier
6- reseal all seams with black marine grade silicone

Water test

I have an additional plyboard to put on top of the stand to give some more strength to the tank

I see no issues with this worst case scenario it doesn't fix it then I'll give up and make an acrylic tank or something and put this as a pond outside as it's not dripping water only very slight weap

I'll update this thread to give anyone in my situation a solution or stop them wasting

Yes it's 94.5cmx50x 66cm

Near 70cm top to bottom, however there's an inch and a half gap for max water level

 

[Valum]

The approach seems sound for a repair. My challenge with a failure like this is understanding its point of origin and why it happened. If you feel the plywood is not damaged then I can understand the decision to move forward. I would suggest taking lots of pictures along the way for your own record. I often find that documenting a build with pictures helps me take a look back years later at how I did something if I can't remember how or why I did something a certain way. Do you have the LxWxH dimensions of this tank you can share? It seems this is a rather tall tank and I am wondering if it is taller than 60cm.

Also I forgot to mention it's 3 coats of A1 pond paint 2L total recommend for the area was 1L

Also when I get the bottom off I will be able to see the bare plywood state were it has leaked, I think it hasn't delaminated due to the fact I did a think coat on the edges of the sheet

 

[Frogspon]

If it didn't work the first time with perfect plywood, it ain't gonna work the next time around using jank left overs. Sorry. That's just the nature of wood

 

[Valum]

If it didn't work the first time with perfect plywood, it ain't gonna work the next time around using jank left overs. Sorry. That's just the nature of wood

But it wasn't the wood that was the issue the wood was perfectly dry it was the joins it was leaking out of, that would be like saying because the silicone between your glass has failed it won't work again with the same glass, obviously with a glass tank you'd check no cracks ect, with wood you check the layers are intact no moisture inside and it's not warped, when I take the bottom panel off it may well split and be warped but at the moment it looks in good condition, you don't know where you wood has been or come from before you buy it for all you know it could have been left in the rain then in a warehouse for a month

If it doesn't feel right I won't use it, but your overlooking the main concern here the materials weren't the issue it was my craftsmanship

I'll rebuild it as said above and if it shortens the lifespan by a couple years so be it I'll rebuild it again with better knowledge

 

[Frogspon]

But it wasn't the wood that was the issue the wood was perfectly dry it was the joins it was leaking out of, that would be like saying because the silicone between your glass has failed it won't work again with the same glass, obviously with a glass tank you'd check no cracks ect, with wood you check the layers are intact no moisture inside and it's not warped, when I take the bottom panel off it may well split and be warped but at the moment it looks in good condition, you don't know where you wood has been or come from before you buy it for all you know it could have been left in the rain then in a warehouse for a month

If it doesn't feel right I won't use it, but your overlooking the main concern here the materials weren't the issue it was my craftsmanship

I'll rebuild it as said above and if it shortens the lifespan by a couple years so be it I'll rebuild it again with better knowledge

I can tell if a piece of plywood has been exposed to extreme moisture before I purchase it and I steer clear.

Looking at those pictures I don't see how the water made it through the seams and didn't come in contact with the fiber of bare wood somewhere.

it doesn't need to have a lot of exposure to be a problem. A tiny bit of water in direct contact will mess that thing up reallllll quick. That tank is only has strong as its weakest point.

 

[Valum]

Ok so verdict is new bottom panel I rushed getting it off and damage the pond paint woods intact and solid, just still a little wet so I'm going to use the piece of plywood I got for the stand as a new bottom and use the old bottom for the stand rest is all ok

 

[Valum]

I'm keen to hear opinions on my new sheet do I coat the entire thing in pond paint then use silicone in-between the joins or join it first then paint it?

My thoughts are that a coating on the top of it may prevent future damage

My only thoughts are the surfaces may not mate correctly?