thanks all, I'm trying to do this on a budget as well as clearing out some old junk I don't need, i figure anything that's useful I'll try to incoporate into this or the pond project, anything that's not hits the dumpster.
also an update on the insul X from home depot, it works at least the rubberized stuff does. so I'll probablly be using that for the build, the container I tested was ~50 gallons so we'll see how well it does with 450gallons lol. Also found out a couple others used it on their tanks on mfk as well, not sure if the one that finished is still running but it did hold water when it was last updated.
now I just have to do the math to see if it's actually cheaper, the 2 I'm comparing to are:
ames blue max-cheapest I've found is 150$ in 5 gallon bucket or 48$ for a gallon bucket, found at ace hardware locally been used in several builds on mfk 100sqft per gallon per coat (applies in 10 mil coats, 2 coats recomended). 2 gallons required for the tank, 3 with the sump
Insl-X Rubber Based Pool Paint - cheapest I've found is 48$ a gallon, found at home depot locally been used twice that I know of on mfk, once in a finished build and worked in a test application. 400-500sqft per coat per gallon 2 coat minimum (applies in 2 mil coats) 2 gallons required for the tank, 3 with the sump
note: I have a little less than a 64sqft coverage area for the tank and I'm guessing about 36 or so for the sump (6x2x1.5) and I want a 20 mil thickness.
at this point hydroban is much more expensive than either of the two above, however, both of the two above are the exact same price for this application, I do get more value in the 5 gallon unit of the blue max, but I haven't checked to see if there's a 5 gallon unit of the pool paint.
also ran into a black jack rubr-coat product but I'd need to test it, super cheap so it's suspicious that it even works for roofs much less my fishies.