What I'm trying to do is using some Azalea root or fingerwood cut a flat spot and be able to stand the pieces up at interesting angles without having to rely on the shape or weight of the wood to do so and also without it resting on the side pieces of glass. I'm looking to have quite a flat bottom which I can put some pebbles on to give it a riverbed type look like in Lauris 'escape'
https://www.ukaps.org/forum/threads/escape.40308/
I do still like the idea of using a piece of ply but don't want to risk it, if only I could find the thread where it was used.
I wouldn't put plywood, even marine ply, in a tank. Waterproof ply is waterproof but certainly not waterproof enough to withstand constant immersion. Could coat it in fiberglass, like people do when making plywood tanks, but I think going a bit OTT.
Why not screw the wood to a piece of slate or a pebble ? Drill a hole in a suitably sized piece of slate or pebble, put a stainless screw through it into the wood. Add some aquarium safe silicone to stop it moving. Place in tank, cover slate/pebble with substrate. Done.
Stainless steel screws are available easily on Ebay (for 1's or 2's) and Screwfix in packs of 100/200 for £10 odd.
Biggest issue is if you don't like the wood placement or wood gets covered in algae, not easy to remove/move as fixed in place.
Personally I would soak the wood for months so get it saturated so it sinks by itself. Boiling can help speed up soaking. Or, as I have done, hollow out non visible areas of the wood, drill holes and chisel and stuff full of lead plant weights. Plant weights can come from either plants you have bought or Ebay. Maybe even put a stainless screw to hold weights in. I used hot glue, but after a couple of years hot glue does work its way loose from wood
Marine ply isn't waterproof; it just uses different glues, is of solid construction so no gaps or filler and the wood isn't treated so it's just like a piece of natural hardwood with glues that shouldn't delaminate - unless you know different?
I had thought about using a slate flooring tile but wood is just easier to drill and fix together, I might look at going down that road if everyone's saying it's a no with good reason. Also no risk of cracking a piece of ply!
I can source stainless steel screws easy enough and have some but getting ones that are of a decent quality is hard; the ones from screwfix will show signs of rust if you leave them outside for a few months. Have you used some stainless screws without signs of rust? If so which ones?
I would have to make sure I liked the wood placement before things were finally glued and screwed!
It's not the fact it floats Ian, I intend to soak it regardless but trying to keep a piece of wood firmly in place I don't think is an easy task unless you can find those couple of pieces of wood that seemingly magically fuse together which I have given up on. I'm looking for the base fixing to support the wood with the fixing so I can put pieces off balance etc.
Aquarium safe silicone is of course a good option instead of hot glue, noted.
i wouldn't go for plywood, not even marine plywood. anything wood needs to be coated
I hadn't planned to coat the azalea root / finger wood which I was going to fix to the plywood so why does anything wooden need to be coated?
As far is i know it's only surface treated
Marine ply isn't treated with anything; it's just a tropical hardwood and glue, 'concrete ply' or shuttering ply is completely different and is full of filler to make it flat and not hardwood throughout. There's lots of different grades of plywood using different glues and constructions but a true marine ply is of the best construction and the price reflects that.
I did this recently, and used egg crate and cable ties
Thanks Tam but wouldn't work for what I'm trying to do
If anyone thinks they have a true knowledge about marine ply then please speak up.
Reading back some of my comments they come across as a bit rude which isn't my intention so sorry if it seems that way!