Planning and Materials pt1 (subfloor)
To build a house you need a foundation so we are going to start with subflooring.
For the water feature I was torn between 'installing' a pool or integrating one into the subflooring using some of the false bottom techniques. I ended up settling on getting a custom rimless Acrylic tank build from glasscages.com. The size I picked was 30lx12.5wx6h, the reason behind the 6"h was because I planned out the total subfloor and substrate height to come out right about there and wanted the top of the tank more or less level to the substrate. I will post picks of the tank early next week, it should be arriving this afternoon actually. (Add picture)
So now we have the pool fleshed out its time to worry about the rest of the sub floor space. Because of the size of this project and the higher then normal weights involved I was not comfortable using an empty subfloor so I decided to hybrid my approach using a filled in false bottom.
Lightweight Drainage Layer Substrate
I've work with various hydro-ball brands and types doing everything from hydro culture through aquaculture but felt that non of what I had used before would really suit this project due to the weight they will add. I decided to try out the LDLS materials because in this design they weight saved was going to far outweigh any minor annoyance of them floating, given the design that wont even be an issue. I order a few gallons of the LDLS from several suppliers (adding the instruction for coarse sizes preferred to them) just to see if there would be any differences. Most of what came in was very small and honestly terribly suited for this project but what I got from black jungle terrariumsupply
was absolutely perfect. It was really large rocks (up to 2") as opposed to the pebbles everyone else sent. Will post pic to show the difference next week. I ordered a total of 15 gallons of the large stuff and am currently half way through washing the lime out of it, this is extremely important as the stuff is made with lime and glass and lime will screw up your ph terribly, it can even dissolve shelled animals on contact. My numbers tell me I need a bit more but I'm not seeing it visually, if I need to get more its been shipped at my door in 3 days on both orders so I'm going to wait and see if I actually need more or not.
Back to plan....
So we have our subfloor fill material I also decided that I would be placing in 4" PVC collars to help give the rocks some structure and to aid in supporting the upper layers, I'm also putting in three larger pipes to be left unfilled, capped, hidden and used to sump out the subfloor. All the PVC has been notched on the bottom to avoid trapping any water. The height of the PVC and drainage rocks should take us right about to 4" (3.78 to be exact) (Add Picture)
Now the next big decision I am looking at is the separation between subfloor and substrate. I have two paths I'm investigating.
1) typical meshing to allow the substrate to drain to the subfloor and then drain from there as needed.
2) using pond liner under the substrate and building up a gradient that forces the majority of the water to flow on the liner into the pond itself. Give the pond an overfloor to the subfloor.
Both these ideas have their ups and downs and I am not 100% committed yet. My general concerns are all around longevity of the project. Growing mildew/mold in the substrate and discoloring the rocks would be bad so I do NOT want to let a lot of water sit in the subfloor for very long. I also feel like having the pond catch all the run off is going to present unknown issues down the road and I'd rather deal with a well known process then 'experiment' with new ideas here. Could definitely use some opinions on this part from more experienced builders.