I'm thinking I might just build the walls separating the land and water with foam and then fiberglass the inside land areas to hold the soil and the side of the foam of the water area will all be covered with zoopoxy, I will sculpt rocks and some areas of of the background will have peat moss pushed into the zoopoxy. Does anyone have any better advice?
Good on ya for having the balls to go big. Also for having the sense to ask for feedback.
I have done this kind of thing about a half-dozen times now. Big vivs, with water areas and separate planting areas. It can go great, it can go to shit. Partly the outcome is design-dependent, partly materials-compatibility dependent, and partly it just depends on how well you execute your craft. Can you read for comprehension, and follow directions.
Of those half-dozen or so such vivs, two (the most recent) have been glass. Specifically, a couple of 36-18-36 Exo's. All the others have been plywood (smallest about 24-24-32, largest about 32-28-60 L-W-H). All have incorporated foam/epoxy "sandwiches" for cliffs, planters, ledges etc. I've used the 307 lite putty, and also a brushable formulation from Smooth-on (Cast & Coat). Mostly it's gone great, but I've gently, lovingly screwed the pooch a time or two. Believe me, I have learned!
My main area of concern is the adherence-compatibility of zoopoxy and whatever resin (I'm assuming polyester...) you used in your glassing. I'm a strident believer in test pieces and "shakedown cruises". Basically - beat the ever-loving shit
out of some test pieces, to see how your materials and methods hold up to hard use. Otherwise you might be tearing into your viv in a year or two. It sucks.
One thing I've learned - if your epoxy won't stick to something, see what will. Polyester / epoxy incompatibility is a well-known thing (I'm a surfer, not just a herper; dings and subsequent fiberglass repair is part & parcel of the hobby/religion/lifestyle/addiction). Silicone doesn't stick well to either
so forget that notion.
Bottom line is, I'm guessing you're gonna need to cover your ENTIRE dirt/water dividing pieces with the same resin you used to glass the hull. That, or accept water intrusion into the seam where they meet - wherever you put that. (I would accept no such thing, but hey - to each their own.) Just roughen up the area of the glassed hull where the divider pieces will join the hull. Same goes for any fake rock - don't use the zoopoxy to adhere it to the glassed hull, if you used polyester resin. Just use more polyester resin to waterproof your fake rock.
I mostly use dry pigments, made for concrete, in my epoxy builds. On my top coat I just sprinkle the powders on, and "dash" them in with a damp bristle brush. The water keeps the brush from getting all gummed up by the epoxy and also helps blend the pigments. The dashing also adds very nice texture to my "fake rock". I've never tried using dry powders on polyester (I'm usually shooting for smooth perfection), but - except for the water - I don't see why it wouldn't work. Just on a superficial coat, after your waterproofing is bomber-solid. Painting polyester is doable, but...you'll have to take care to get a paint that won't get soft with immersion or constant humidity, AND is fish-safe. Surely doable, but the quest might
grow some hair. I like my dry pigments.