foam padding needed for plywood aquariums?
- Thread starter vincel892
- Start date
There's no way the plywood itself will crack...that's one of the beauties of plywood construction...but I always put a rubber layer between tank and stand in an effort to prevent the dreaded "microfractures" in the epoxy water-proofing layer that so many builders seem to mention. Similarly, I do everything possible to minimize moving the tank after it's built, for the same reason. The new low-VOC epoxies available today actually make it possible to build a tank and then seal/waterproof it right where it is destined to be throughout its working life. I would never attempt to move a larger (over 4-foot long) tank once it's completed.
Does the rubber help in this regard? I dunno...I suspect it makes some slight difference...but adding it is so easy and so inexpensive that I can't understand why anyone would skip that step. You can buy rubber baseboard moldings by the foot or by the roll, and they are dirt cheap. Very easy to trim off the raised lip along the bottom edge, and then splitting the molding in half lengthwise gives you long strips that are the ideal width to glue to the top edges of the 2x4's or 2x6's that many stands are constructed out of. Takes almost as long to type it out as it does to actually do it, and for me the extra peace of mind is worth it.
Does the rubber help in this regard? I dunno...I suspect it makes some slight difference...but adding it is so easy and so inexpensive that I can't understand why anyone would skip that step. You can buy rubber baseboard moldings by the foot or by the roll, and they are dirt cheap. Very easy to trim off the raised lip along the bottom edge, and then splitting the molding in half lengthwise gives you long strips that are the ideal width to glue to the top edges of the 2x4's or 2x6's that many stands are constructed out of. Takes almost as long to type it out as it does to actually do it, and for me the extra peace of mind is worth it.
Great info. But I've already failed with not moving the tank after epoxy lol. Have flipped it down to get the front glass on. Will try my best to not touch it after this though. I've been told that macropoxy is much more flexible than something like pond shield so maybe less chance of microfractures ? I'll look into the baseboard molding
Lol, I don't think that's necessarily the kiss of death for your tank. I always insert the glass with the tank face down also, and then after the silicone is cured I flip it backwards into place. I think it is important to have sufficient manpower, i.e. at least one man at each end, to do this without flexing the tank and thus causing the microfractures. It becomes more problematic when the tank has to be moved indoors, around corners, up/down stairs, etc. since preventing the flex becomes almost impossible.
For those that question this or think it's paranoia...stand next to an all-glass tank, grab an upper corner, and see if you can produce any discernible flex. Now do the same thing with a plywood tank. The difference is astonishing. It's one of the main reasons for top-bracing, IMHO, in addition to preventing bowing.
I'm toying with the idea of applying a coat of liquid rubber to the inside of a tank that has been epoxy sealed. That flexible skin on top of the tough epoxy might be the ultimate combination to withstand leaks caused by microfractures; I haven't tried it yet, and can't find any evidence that others have either.
For those that question this or think it's paranoia...stand next to an all-glass tank, grab an upper corner, and see if you can produce any discernible flex. Now do the same thing with a plywood tank. The difference is astonishing. It's one of the main reasons for top-bracing, IMHO, in addition to preventing bowing.
I'm toying with the idea of applying a coat of liquid rubber to the inside of a tank that has been epoxy sealed. That flexible skin on top of the tough epoxy might be the ultimate combination to withstand leaks caused by microfractures; I haven't tried it yet, and can't find any evidence that others have either.
When I started building plywood tanks, about 30 years ago, I used a Pratt & Lambert epoxy called Palguard. Miserable stuff to work with, copious toxic fumes, not the best in terms of application ease...but unbelievably tough and durable. Haven't seen it for sale recently.
I built a couple tanks in the past couple years using Pond Shield; easy to apply, virtually no fumes, and working like a charm so far...but its only been 2 years for the oldest tank with this stuff, so not really a long-term test.
My current project is using Interseal 670HS, which I can't really comment on yet. It goes on beautifully, and the fumes, while considerably more than Pond Shield, are still far from unbearable. Working with good ventilation makes it doable indoors. I've read a couple reports from happy tank-builders who have used it, and my limited testing has shown it to be non-toxic, with good adhesion to silicone. For me, two of its biggest pluses are the fact that it is available locally, and is relatively inexpensive compared to Pond Shield. It comes in several colours that should work well in aquarium interiors. I have high hopes for this product!
