My new 2600 gallon plywood tank project

[flip_mode]

i agree i think it would be more cost effective and time management and peace of mind if you just go ahead and drop more ply on the back .

 

[imacskye]

There's not much of a smell off epoxy, it's polyester that makes your eyes water!

 

[CJH]

Considering that I do still suspect the voids in the plywood at ths point (Those could easily flex/collapse) I may either lay down another layer of 3/4" plywood on the back wall and 1 side wall (the one with the bulkheads is already 3/4" ply) then doing those walls again in pond armor. Or fiberglassing is another good option.

Only reason I would hesitate on the fiberglass is the smell that would overpower the house. Can't really have that. The Bondo was bad enough on it's own.

Like another poster said, you can wet out fiberglass reinforcement with epoxy resin and not have the odor issues. In fact I don't believe you could even get a polyester or vinyl ester resin to stick to the Pond Armour. Epoxy will stick to cured polyester but polyester won't bond to cured epoxy.

And fiberglass reinforcement would deal with voids better than plywood reinforcement from the outside.

I also don't think switching to a totally different type of sealer is a bad idea, like if you used a single component bituminous product like the Zavlar/Liquid Rubber.

It is not uncommon for multiple layers to be used in water containment systems. Like a solvent based epoxy for penetration, 100% epoxy resin for build and in some cases for fiberglass reinforcement and then final layers of bituminous or polyurea sealers.

In your case you still have this option since bituminous or polyurea sealers can go over epoxy. If you had started with bituminous you couldn't get anything else to stick to it. The biggest problem you'll have with it is that it won't stick to your silicone. But neither will epoxy/fiberglass.

Remind me, did you use Dow 795 when you put your windows in the second time?

The only product I have heard of going over silicone is a 2k polyurea. I'm not sure if even that would work over the 795 since it stays so pliable.

You might see if there is a pond company in your area that sprays polyurea. Maybe at least do a test to see if it will go over 795.

 

[sross]

For fiberglass, on my tank I used a Marine epoxy for fiberglass, US Composites. It had almost no smell.

 

[Aquarist Andy]

Just finished reading this build. Nice project, certainly is setting you some challenges VL. Hope you manage to resolve the tank sealing issues.

Best of luck, Andy.

 

[VLDesign]

I will check into the expoy and matting then for sure. It's sure can't hurt.

 

[Zari]

Oh jeeze my little comment caused a big discussion =O
Anyways best of luck. I plan to fiber glass my tank when I finally get a chance to make it in March-April or so just for the added security. It seams to be the most reliable way to seal a tank right off with the least bit of trouble of leaks and it cost about the same as it would to coat in an alternative.

 

[MaddMaxx]

I remember thinking on your first build that the cement board was way overkill, but maybe that was what prevented the flex/void issue. If you're going to add more plywood (with the possibility of more voids) why not just go back to cement board?

 

[VLDesign]

Found the leak.

Scraping the corners this afternoon near the bottom abdout 11' from the left when all of a sudden the scraper blade sank into the corner a bit more than usual.

After some more scraping I ended up with a 3' section (diameter). All of which had wet plywood underneath it. Hard to tell if the bondo failed or what but it's just about useless in this area and cracked in the seam. Will not be filling the seam with bondo again just PA and the tape. The area also feels a little loose so I will run some more screws into the area as well.

Also looks like the bondo in that area wasn't mixed correctly as it still had that fresh bondo odor to it and the PA didn't stick to it very well at all.

Letting it dry out over night then I will sand the area down, and put some more fiberglass tape in the corners and reseal the area.

 

[broken]

Found the leak.

Scraping the corners this afternoon near the bottom abdout 11' from the left when all of a sudden the scraper blade sank into the corner a bit more than usual.

After some more scraping I ended up with a 3' section (diameter). All of which had wet plywood underneath it. Hard to tell if the bondo failed or what but it's just about useless in this area and cracked in the seam. Will not be filling the seam with bondo again just PA and the tape. The area also feels a little loose so I will run some more screws into the area as well.

Also looks like the bondo in that area wasn't mixed correctly as it still had that fresh bondo odor to it and the PA didn't stick to it very well at all.

Letting it dry out over night then I will sand the area down, and put some more fiberglass tape in the corners and reseal the area.

Awesome!!!