Hello friends. I've been on this site and I've been seeing a lot of amazing plywood aquarium builds. I want to take that step and do one myself. I'm interested in using liquid rubber to waterproof the tank. I also found a lovely place here in Georgia that sells the 1/2" 4'x8' cell cast acrylic sheets as well priced at $210 a sheet. First, is that a good price. I've shopped online and I've seen almost double for that size. Anyway, my concern is the liquid rubber with the acrylic. Am I going to have to use some type of fiberglass resin as I'm kinda afraid to go that route due to me never having any experience in the matter? I've seen a post where a guy used a combination of liquid rubber and fiberglass resin. I just want to get some different opinions out there. I've looked at the pros and cons and the only thing that it talked about was the incompatibility with silicone. That's the only thing. Is there a way around this? I want a tank about 500 gallons but I want to start with something smaller. Something around 150 - 200 gallons. Also, will it be okay to use a plywood tank with saltwater fish etc.? Thanks for your time.
Plywood Build Question
- Thread starter Feezy3000
- Start date
The only question that I know enough about to answer is the last one: yes, saltwater in plywood is fine. Good luck! and I expect many pictures as you build and get answers to your other questions! 
If you're going to go saltwater, I think it might be best if you go with marine epoxy (ex. West systems epoxy) and fiberglass. Then paint it whatever color with epoxy paint (ex. Sweetwater). The reason I say this is I to am planning a saltwater reef build and upon MY research I have found that liquid rubber (or zavlar in my case) will cause phosphate problems. In sw tanks the phosphate will cause green hair algae to grow and Green hair algae will break down the zavlar coating. Just to note I did look at zavlar product sheet and it says its fine with salt. And I emailed them and they just told me what the spec sheet read. BUT I emailed someone who used zavlar on a sw build and he was the one who told me about the algae. Either way I dont want to risk it so ill be using west systems and Sweetwater until I find a liquid rubber product that works
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I would find out the brand of acrylic and research from there. I have read that their are some "cell cast" acrylics imported from China that are of very low quality. That would be my biggest fear if shopping for acrylic.
As far as liquid rubber being compatible with silicone, there were some posts from their distributors about how to deal with this around four years ago. Or maybe they were emails pasted into a post on this site.
I remember two of the recommendations and neither involved silicone. One was to use a rubberized caulk and attach the glass or acyrlic directly to the wood and then apply liquid rubber up to and over the caulk. Liquid Rubber will stick to cured rubber caulk.
Another rep suggested something very similar but said to use a quick cure polyurethane caulk. Again, attach glass directly to wood and then apply liquid rubber up to and over the polyurethane caulk.
Then I and others chimed in and said that if it were us we'd take it a step further and seal just the wood around the window area with epoxy resin. Only the areas where the rubber caulk would be sealing the window to the wood. I think Ross took that advice when he could get a good seal but used polyester resin (sometimes called "fiberglass" resin) to seal the wood.
I hope this helps. I really don't have any advice regarding your other questions.
Thank you... I've never used epoxy and fiberglass. I've heard about it but I'm a little nervous about using it as I don't know what I'm doing. Maybe when you start your build, you will have pictures and advice on how to use it. If you have anything for me that will help, that would be great. Thank you for your advice.
I fiber glassed the inside of the stand I built for my little sister. My 7 year old daughter even helped me. It wasn't that tough. The only place I found it to be a bit challenging was fiber glassing over outside corners. On inside corners you can tuck the glass fabric into the corner and not have any air bubbles. On outside corners the fiber glass wants to bubble up. You either need some way to hold the fabric taught or do the outside corners in two separate applications of the resin letting the first application dry first... so the first application will hold the fabric in place while you are pulling the fabric taught while applying the second coat.
What about the Ames Blue Max Liquid Rubber? It's blue in color and very strong. Also, I saw on another forum that they have something else that you can use for that very purpose. I don't know how true this is. I'm just very interested in using the product. I've never dealt with epoxy before. It seem a bit hard to mix and work with. I'm sure that they have tutorials on it non the less. Thanks for your feedback.