Liquid Rubber for water-proofing tanks and growbeds?

[Cai Robertson]

     I was going to use epoxy to waterproof my plywood tanks and growbeds, but I am concerned about BPA ending up in my fish and vegetables.  I found something called Liquid Rubber at Home Hardware. It's about half the cost of epoxy, doesn't off gas (Zero VOC), is water based and says it is safe for ponds.  There is no information to be found about it being foodsafe.  I even called the number on the can and I was told that it is being used fish tanks, but could not say it was food safe.  The only other product I can find is Pond Armor, which is a VOC free epoxy sealer, and is said to be safe for hydroponic use.  The Pond Armor costs about twice as much as normal epoxy.  I would really like to use the liquid rubber, but want to have some peace of mind.  Any input would be appreciated.

http://www.liquidrubber.ca/

http://www.pondarmor.com/index.htm

[Pices]

What are the dimensions of your tank? I think most folks use 3/4 inch plywood, but depending on the depth (ie water pressure) and length of sides, they may reinforce it with some 2X4s.

Cai Robertson said:

  I am wondering what might be recommended as far as plywood goes.  I think I might be able to get away with 3/4 inch but I am not sure for the longer sides.  1 inch costs about twice as much.  I might go with the 1 inch just to be safe but if you know of any projects involving plywood tanks and beds, I'd love to get a link or two to see how they worked out.  I will be starting a blog post for this project. 

[Cai Robertson]

The inside dimensions of the fish tank will be 3'4 (W) x 6'5 (L) x 19" deep to make a tank around 250 gallons.   The walls of the tank will go 4" higher than the water level, making the tank 2' high from the outside.  Because I am tight for space,running 2x4's on all sides will take an additional 7" each way,  I am thinking about running a few metal bars up the sides of the tank and attaching some thin cables on the top and bottom to hold any outward pressure and buldging.  I am thinking now that 3/4" should be fine with enough bar.  I will probably use 1" on the bottom of the grow beds, which sit on top, to avoid any sagging. 
 
Bill Barker said:

What are the dimensions of your tank? I think most folks use 3/4 inch plywood, but depending on the depth (ie water pressure) and length of sides, they may reinforce it with some 2X4s.

Cai Robertson said:

  I am wondering what might be recommended as far as plywood goes.  I think I might be able to get away with 3/4 inch but I am not sure for the longer sides.  1 inch costs about twice as much.  I might go with the 1 inch just to be safe but if you know of any projects involving plywood tanks and beds, I'd love to get a link or two to see how they worked out.  I will be starting a blog post for this project. 

[Cai Robertson]

The front porch system is going to wait now.  I have scored a 1000 gallon cylindrical tank that I am going to put in the ground in my back yard.  I am going to build a 12' X 30' hoop house over it and put trout in the tank.  I'll be getting started as soon as I can dig. 

[TCLynx]

What sort of filtration are you going to have for the trout system, be sure you get that part of it going before you think about putting the fish in the tank.

[Cai Robertson]

Media beds are not sufficent?

 
TCLynx said:

What sort of filtration are you going to have for the trout system, be sure you get that part of it going before you think about putting the fish in the tank.

[markaponics]

The liquid rubber looks interesting but at $50 a gallon I think that a pond liner might be more cost effective. It says 15 sq.ft / gallon. No not sure if that includes the 3 coats it says for a pond setting.

[TCLynx]

I didn't see any comments about filtration or media beds in the post I replied to and haven't had time for looking back through threads lately.

If you are using the appropriate amount of media beds for the amount of fish tank or fish to be stocked then they should be sufficient.

Cai Robertson said:

Media beds are not sufficent?

 
TCLynx said:

What sort of filtration are you going to have for the trout system, be sure you get that part of it going before you think about putting the fish in the tank.

[Cai Robertson]

I plan to stick to the 1 to 1 ratio and adding vertical towers later on.  I'm hoping that 7 feet in the ground should keep the water pretty cool.  I will be ready to add evaporative cooling and/or a diy water chiller if need be. 
 
TCLynx said:

I didn't see any comments about filtration or media beds in the post I replied to and haven't had time for looking back through threads lately.

If you are using the appropriate amount of media beds for the amount of fish tank or fish to be stocked then they should be sufficient.

Cai Robertson said:

Media beds are not sufficent?

 
TCLynx said:

What sort of filtration are you going to have for the trout system, be sure you get that part of it going before you think about putting the fish in the tank.