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

 

[Rmckoy]

I’ve researched this idea many years ago .
and the reason most when with a large plywood tank was bigger ....

My build idea was 1000-1500 gal
There was a rubber like roll on membrane but can’t remember the name .
1 viewing side I was going to use 3/4” thick glass .
the issue was the silicone to seal the glass wouldn’t adhere to the rubber like sealer membrane .
so finding a different way to glaze the glass into position . While preventing any leaks .

I gave up on this idea for many reasons
1) cost
2) I didn’t want to ever move it but was planning on moving from that house
3) cost of stocking after it was built

I have a 230 gal now and it’s plenty big enough and maintain

 

[Joekovar]

Typically plywood tanks seem to have 2x4 walls built like house walls, where yours appears to have been built with the 2x4's "on the flat".

There's a significant difference in strength between the two orientations. A 2x4 in a wall orientation gives 3.5" of wood to hold up against the water pressure, which will be greater at the bottom of the tank. With a "on the flat" orientation you have less than half of that, at 1.5".

I don't think the framing is strong enough to keep the bottom of the tank walls from bowing out. It's not going to take much deflection to crack the waterproofing. I think this is why you got a leak at the bottom.

I think the bottoms of the walls need to be stiffened. I would try adding a 2x4 frame around the bottom, so that the bottom is L shaped, before putting a new bottom on. I'm honestly not sure whether that's going to do it though.

 

[Valum]

Typically plywood tanks seem to have 2x4 walls built like house walls, where yours appears to have been built with the 2x4's "on the flat".

There's a significant difference in strength between the two orientations. A 2x4 in a wall orientation gives 3.5" of wood to hold up against the water pressure, which will be greater at the bottom of the tank. With a "on the flat" orientation you have less than half of that, at 1.5".

I don't think the framing is strong enough to keep the bottom of the tank walls from bowing out. It's not going to take much deflection to crack the waterproofing. I think this is why you got a leak at the bottom.

I think the bottoms of the walls need to be stiffened. I would try adding a 2x4 frame around the bottom, so that the bottom is L shaped, before putting a new bottom on. I'm honestly not sure whether that's going to do it though.

Hey thanks for your response, I see your point there is a little gap between the walls the tank rests on its surrounded by 3 solid brick walls so if I made it so it's a tight fit I shouldn't encounter these issues you talk about but definitely worth taking into consideration for my next build thanks

As you can see on the image the only gap is the front and left side if I can wedge the left up it should transfer the weight to the wall too

 

[Adolfo]

I think you need to reinforce all the corners

 

[Joekovar]

Hey thanks for your response, I see your point there is a little gap between the walls the tank rests on its surrounded by 3 solid brick walls so if I made it so it's a tight fit I shouldn't encounter these issues you talk about but definitely worth taking into consideration for my next build thanks

As you can see on the image the only gap is the front and left side if I can wedge the left up it should transfer the weight to the wall too

I understand why you did it that way now.

That gap may have been just enough to let the liner tear. About 1/4"?

 

[Valum]

I understand why you did it that way now.

That gap may have been just enough to let the liner tear. About 1/4"?

Yeh I assume your right that's the corner where the water damage was most extensive too so it definitely makes sense that this would be the cause and yeh my thought where more surface area as if I did them the way you mentioned I'd lose alot of realestate in the tank I think what I will do is wedge wood the full width of the side braces to that the force is transferred to the brick wall too

 

[Valum]

Might also as some further bracing around the mid section too

 

[jtf74]

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

Can't tell from your pics if this has glass front or is a look down. If a look down get yourself a 40 mil pondliner and forget the paint or buy a plastic livestock water tank. You can use metal strapping to prevent bowing. You'll need old carpet or some padded underlayment for a pondliner also.

 

[Valum]

Can't tell from your pics if this has glass front or is a look down. If a look down get yourself a 40 mil pondliner and forget the paint or buy a plastic livestock water tank. You can use metal strapping to prevent bowing. You'll need old carpet or some padded underlayment for a pondliner also.

It does have a glass front finished my repair as stated above this did cross my mind however decided against it

 

[Valum]

My advise so far is take your time and ensure everything is 1000% otherwise you'll end up with regrets and having to do things over also if you go for black pond paint don't bother using clear silicone it looks horrid use black!

 

[Valum]

Also personally I'd go with silicone over fibreglass, alot more plyable and no risks of the material moving around too much

 

[Valum]

8 hours in no signs of any leaks yet it's still early days

 

[Valum]

Okay so got home from work and noticed 3 minor constantl leaks from between the silicone holding the glass on and the front panel

My approach to this was an attempt at silicone front the outside while filled this failed for obvious reasons I tried applying pressure with wood screwed into the frame no joy because silicone takes so long to dry out

Don't judge my stupidity too much it was the only option I had

Tried baking soda and super glue and baking soda with surprising results just ran out of glue

I'm going to pick up some epoxy tomorrow and apoxy it from the outside simily things I've seen used on full water tanks with a much more drastic leak

I'm not too concerned with the wood becoming damaged as both sides of where the leak is coming from are coated in pond paint
Once cured I will apply a layer of silicone on top

Will update tomorrow how this goes

 

[AlexG]

I think this is a good time to hit the pause button and take a deep look at this tank. If its leaking on the glass seal the only way to properly resolve the issue is to remove the glass and silicone seal then determine why it failed. What thickness of spacer did you use between the tank and the glass to control the seal thickness? How many weeks did you wait for the seal to cure before attempting a fill test? If the tank was moved a lot due to the previous leak then those movements could have torn the silicone seal on the glass. Three leaks on the glass seal might just be the beginning and with a previous seam failure It might be best to take a step back. The make do and mend approach might not be the best way forward to get this tank running. I cannot tell from the picture for sure but if you already have life in this tank its way to early for that and the tank should be tested with nothing in it for a few weeks. I know its hard to wait but its the best approach to ensure your tank is going to function properly. I am in the process of building new tanks with a temp tank with fish and corals that needs to be transferred to a proper aquarium system but I am testing the new system for several weeks/months before I attempt to add salt or life to the system.

 

[Valum]

I think this is a good time to hit the pause button and take a deep look at this tank. If its leaking on the glass seal the only way to properly resolve the issue is to remove the glass and silicone seal then determine why it failed. What thickness of spacer did you use between the tank and the glass to control the seal thickness? How many weeks did you wait for the seal to cure before attempting a fill test? If the tank was moved a lot due to the previous leak then those movements could have torn the silicone seal on the glass. Three leaks on the glass seal might just be the beginning and with a previous seam failure It might be best to take a step back. The make do and mend approach might not be the best way forward to get this tank running. I cannot tell from the picture for sure but if you already have life in this tank its way to early for that and the tank should be tested with nothing in it for a few weeks. I know its hard to wait but its the best approach to ensure your tank is going to function properly. I am in the process of building new tanks with a temp tank with fish and corals that needs to be transferred to a proper aquarium system but I am testing the new system for several weeks/months before I attempt to add salt or life to the system.

I might go pick up a temp tank

 

[Valum]

I think this is a good time to hit the pause button and take a deep look at this tank. If its leaking on the glass seal the only way to properly resolve the issue is to remove the glass and silicone seal then determine why it failed. What thickness of spacer did you use between the tank and the glass to control the seal thickness? How many weeks did you wait for the seal to cure before attempting a fill test? If the tank was moved a lot due to the previous leak then those movements could have torn the silicone seal on the glass. Three leaks on the glass seal might just be the beginning and with a previous seam failure It might be best to take a step back. The make do and mend approach might not be the best way forward to get this tank running. I cannot tell from the picture for sure but if you already have life in this tank its way to early for that and the tank should be tested with nothing in it for a few weeks. I know its hard to wait but its the best approach to ensure your tank is going to function properly. I am in the process of building new tanks with a temp tank with fish and corals that needs to be transferred to a proper aquarium system but I am testing the new system for several weeks/months before I attempt to add salt or life to the system.

I didn't use any spacers of anything like that please advise me on best practices for mounting the glass I've taken your advice and moves live stock to a makeshift Frag tank

Going to take my time in the fix

 

[Valum]

Looks to me like it's forcing it's way between the silicone and the plywood, the seams behind the glass also look like the silicone missed them when I installed so think when I get it off I'll use a thinner bead and more pressure

 

[Valum]

So I've been taking my time I've removed all the silicone and sanded the area down just need to put a silicone order in aswell as a pond paint order

 

[Valum]

Woodfiller has cured time to sand it down tonight

 

[sean151]

Are you strengthening the bottom section. Of the wood where the glass meets the wood? Wood flexes and glass doesn't, if you don't overbuild in this section you can get a failure point along the bottom where it starts to delaminate even after waiting the proper cure time.