Seal concrete block tank?

[Josiah Sherman]

Hi to everyone, this is my first post

I live in central Texas and I'm building an aquaponics system. I started by building a concrete block tank and then built a greenhouse over the tank with lots of space for grow beds. When I originally built the tank I didn't realize that I would need to seal it from the concrete. I have now learned that the concrete block has a very high pH and will hurt the fish and plants.

I have looked a little at SanitTed PermaFlex and Epoxy Paints.

If anyone have tried these product or if you have used another product that has worked well, please let me know.

I include a picture of the tank and greenhouse. Thanks!
Josiah

[Ian Cameron]

Hi Josia, we use epoxy paint on our concrete salmon rearing raceways Just make sure you prime it first or it will flake off. This stuff is not cheap.

[George]

Is that a 6-foot ladder in the tank?

[Josiah Sherman]

Hi,

I like the idea of epoxy, but I'm worried that the block is too pouris, has anyone here used epoxy paint on concrete block before?

The latter is an 8 ft latter! Nice and deep.

[Bob Campbell]

Use Thoroseal. 

I built an above ground boi filter for my Koi Pond about 7 years ago.

It's 40 inches tall 7 feet long and 4 feet wide. (5 rows of 8x8x16 concrete block)

I laid the concrete block up dry.  Filled the cavities with concrete.

No mortar was used between the blocks.

I then put three coats of Thoroseal on the inside and it has never leaked.

Thoroseal is used to make cisterns waterproof.  This is the purpose it was designed for.

It does not require skill to apply.  I use a wide paint brush.

I have also used it to water proof old stucco where the paper moisture barrier has failed.  It worked very well.

My feeling about epoxy paint is that it will fail.

Here's a good video to watch

[Josiah Sherman]

Hi Bob,

I had originally planted to use Thoroseal, but because worried that the pH of the water would be effected too much and hurt the plants. What is your thoughts on this? Have you had any trouble?

Thanks,
Josiah

[Bob Campbell]

I had no problems, but I filled and drained the tank several times.  

I just edited my first comment to include a video.

I wish I had measured the PH when it was new, but I never did.

Why did you make it so deep?

Josiah Sherman said:

Hi Bob,

I had originally planted to use Thoroseal, but because worried that the pH of the water would be effected too much and hurt the plants. What is your thoughts on this? Have you had any trouble?

Thanks,
Josiah

[Jake Schneider]

Dude! Is that a fish tank or swimming pool?   Your going to need a deep sea fishing pole to get fish out!!  Or is that a sump tank?  Wow, that's huge.

[Jon Nose]

Pond liner ???

[Josiah Sherman]

Hi Bob and Jake! Good to be friends

When I started digging, it was VERY hard solid rock. Then when I got to 5 ft it was so much easier I decided to go deeper and make the tank narrower.

I plan to have a frame with a net at the bottom that I can pull up when time to harvest or check on the fish!

The tank is the sump and fish tank tank in one.

[Josiah Sherman]

Hi Jon,

I had thought about using a liner, but was hoping not to because when I built the tank I built all the drains and water lines into the block, a total of 9. So I'm not sure how I could seal the liner around all the pipes.

[Jon Nose]

Lots of aquarium safe silicon :)

Josiah Sherman said:

Hi Jon,

I had thought about using a liner, but was hoping not to because when I built the tank I built all the drains and water lines into the block, a total of 9. So I'm not sure how I could seal the liner around all the pipes.

[Bob Campbell]

I smoothed the Thoroseal right up to the 2" PVC pipes in my bio filter.  I had my doubts when I did it, but years later I can still say there has never been a problem.

Josiah Sherman said:

Hi Jon,

I had thought about using a liner, but was hoping not to because when I built the tank I built all the drains and water lines into the block, a total of 9. So I'm not sure how I could seal the liner around all the pipes.