Lol, beats me, Mr. MSDS!
I've never tried nor even heard of either one.
Both of those appear to be designed more as adhesives; the second one is even referred to as a glue. I have no idea if they can be applied to large surfaces as a waterproofing layer. I'm not exactly encouraged by phrases like "water resistant".
And even if they will technically water-proof a surface, you also need to look for a product which is tough and resilient, non-toxic, able to withstand bangs and bumps and scrapes caused by rocks, etc.
Since you need to order your supplies online, why not go with a product that has a good reputation behind it for this type of work? Is Pond Armor/Pond Shield not available to be ordered? It works well, is easy to apply and work with, comes in colours. My current favourite is Interseal; I actually can buy it right off the shelf here in the heart of deepest, darkest Canuckistan but I also ordered it when needed because I (foolishly) wanted to try colours other than black.
Interseal's website is/was chock full of very complete information on this product; it's absolutely non-toxic once cured; how about those products mentioned above? It's relatively low in VOC's, so application is less dangerous than many other epoxies; how about those things? It retains a certain degree of flexibility to resist cracking; those others?
If you want your build to be successful...don't experiment with unknowns. Use stuff that works, and that has been proven effective by others before you. I think that many or even most of the failed tank builds that we hear about...and there are plenty more that we
don't hear about!...are caused by people deciding to "try this stuff" or deciding that the manufacturer's instructions are wrong and that they know better how to apply, or what temperatures should be maintained, or how long it takes to cure, or any of a multitude of other potential problems.
Building a tank that is well-designed, properly constructed and waterproofed using proven techniques and materials is very simple, especially since you are a bit of a "woodchuck" already; I'm hoping you prefer to be called that species of rodent since you didn't like "Guinea pig".
But...attempting to correct or repair a problem caused by the "good enough" or "let's try this!" mentality is a major PITA. If you are going to do it...do it right!
