DIY Plywood 1200Gallon -Officialy Started

  • We are currently upgrading MFK. thanks! -neo
Sorry to hear you have problems. Using the fibreglass on the inside will be much better for sealing and impact resistance but will do very little for structural strength. For structural strength, it is best used on the out side.That being said, the timber construction of the tank should be built to take the weight by itself. Your problem is the free floating seems and use of OSB type ply. The seems for the plywood should not be floating like they are as they will flex with the weight. They should be supported 100%. The flex is exaggerated even more as the OSB ply you used is not as rigid/strong as higher grade plywoods. In your case, I probably would have used 2 layers for the floor. The 1st running parallel to your floor joists with the seem shared on the joist itself. Then run a 2nd layer at a 90 degree angle to the first. It would hold a lot more weight. At the very least, install supports between the joists to support the seem.
 
Well spotted GreenTerra, I looked back through the construction pics and did not notice that design flaw.

I thought the OSB and glass would be OK but the unsupported seams/joins in the OSB floor may be the issue with all that weight.

We will have to wait and see what Tor thinks and hear where the leak is coming from.
 
Hello fellahs. Thank you for all your innput. I did 18mm osb to be on the safe side, but the seams has flexed a littlebit, not much, but littlebiit, i think we are down to mm`s.. About the cracking idea i had, I think i might have bin wrong, as i have bin into the tank, with loop and flashlight to find something that could look like a leak, but nothing, no cracks, no wounds, no nothing.. But i did measure the leak with a bucket, and at 80% full, it dripped 1 liter in 24 houres, and is a reall really small leak, impossible to find to say atleast.. I will add a drawing i made, youst to outrule the window completley.

As far as i can see, it is impossible that a leak under the tank, can come from the window. The way i made it, if there is a leak in the window, is has to come in the aperture(lightopening), i cant see ANY other way.. So in my head, the window is 100% outruled. If it were to come from the window, it would have to travel through the aperture(lightopening), and then down again, under the fiberglass\epoxy etc, and if that were to be the case, i would see it.. When i filled it the second time, i did put toiletpaper on wood with the window, so that i would instantly see if there was something coming from there, but the toiletpaper stayed dry all the way up to the 80% mark, and being dry for the 2 days i had water in it.

I have now supported the seams btw.. Did put extra 2\4 between the 2\4 that were there already, so now there is only 20cm between each 2\4 on the bottom..

I did put another layer of epoxy on the bottom 2 days ago, so im ready to testfill again tomorrow ;) Lets cross everything we have! I really want to start on the filtration now, i could have already done it, but my mindset hasnt really bin there since its not even holding water properly.

Tegning i profil.png
 
Looking back at your build the OSB seams run perpendicular to the supports. I can't believe it could leak between the seams. Did they have tongue and groove edges or are they just butt ends? When I used OSB for my tank floor my only seam was tongue and groove so it was very rigid. Also if you have two layers of fiberglass covering everything it's unlikely it could leak through. Did you cover the entire tank with FG or just certain areas? After going through those possibilities then the only place left is the glass. :confused:
 
It didnt :p hehe.. Hopeless! 40% Full = no leak, 50% full, small leak. I will check out the area inbetween, maybe its a preassure fault, or just a wound in the walls, i dunno.. A guy that has built something similar will come around on friday. In the mean time it will stand 40% full. The funny thing is that the water comes under, no sign in the walls, so how could it be a wound in the walls.

Can water travel under the epoxy? Between the epoxy and the wood? I didnt think so, since the epoxy adherds to the wood. But can someone with experience on these things chime in pleace!
 
The epoxy soaks into the wood so I don't think there could be a gap between the epoxy and wood. It sounds like it could be some flexing of the OSB under load. But from your stand it doesn't seem like there's much room for flexing. However the leak must come from somewhere. So my guess is the seam between the OSB boards in the floor. Was the fiberglass put on completely covering the tank? Or did you leave out gaps? This is really perplexing because from what you described it shouldn't leak.

Have you attached the tank to the stand? If not can you lift it and place some plywood underneath it? I put a layer of 1" polystyrene sheet for insulation and it also supports the floor.
 
It is attached to the stand yes :) The tank was fiberglassed and coated in epoxy, all over! 5 layers of epoxy, 6 on the bottom.. I think this has to do with the window somehow! I do not have a clue how its possible, but the water dont lie! My next step i think will be cutting out the glass, lay it down inside the tank on some 2\4`s, get all the silicone away, sand it down, put a few extra coats of epoxy on there, and attach the window again.. Testfill, if still leaking somewhat, sand the entire tank down(exept the floor since i already did that)and put an extra layer of epoxy..If it then leaks,i will be like "wtf"!!!!!!!

This tank is litteraly bulletproof, i just couldnt imagine anything leaking! Ive read thousands of threads on here, and done everything the failures didnt do, but still...WTF :WHOA:
 
You must log in or register to reply here.
MonsterFishKeepers.com
Top Bottom