Alternatives to using liners in cement grow beds ??

[Jimmi Jones]

Hi all, greetngs from Belize.

 

I am still working on my small commercial raft system. I am weighing my options whether to use liners or some kind of cement sealer that could be used instead of liners that would be plant and fish safe, any suggestions? The challenge I have is the liners would need to be imported to Belize as I have not found anything suitable.

 

Thanks

 

Jimmi

[Wayne]

My wife's uncle has worked with fiberglass most of his life, boats mostly. He has now started spraying a fiber film, almost like painting. He sprays wood decks and porches near the ocean and the product has a 30 year  warranty I believe. He has also spayed inground pools for people that are either tired of replacing the liners or have leaks in their concrete pools.

 

I'm sure there are others doing the same in your area. You can get different colors added to the mix as well.

It is pretty pricey but if durability is your main concern it can't be beat. It will conform to basically any form you apply it to, no seams to worry about.

 

I can give him a call and ask what the average cost per sq ft would be. The initial setup of the equipment would be the most expensive part. 

[TCLynx]

Is the coating fish/food safe?

[Wayne]

To the best of my knowledge it uses the same as the materials used in normal fiberglass construction. Except instead of fiberglass matting, the individual fibers are blown though the sprayer and is injected with the resin at that point. Might have a little longer curring time.

 

I have not been involved with AP long enough to know if normal fiberglass is fish safe but have seen videos of fiberglass tanks being used. Just because it was on Youtube doesn't make it proper though. 

[TCLynx]

Well I know that they make fiberglass tanks but they are usually gel coated over the fiberglass resin and fibers to make it durable and fish safe.  Seems to me if you already have a sound concrete tank that you might simply coat it with a fish safe coating rather than having to fiberglass it and then coat it anyway.

[AlbertF]

I used an iso resin on my FT, it is FDA approved.  Locally it was $40/gallon.  Add a few more bucks for catalyst and surface coat. 

If you wanna get certified, you will need to have someone ship in some LDPE liner.

[Wayne]

Yes it would probably be cheaper to use some other coating. I think the application would be cost prohibitive for most of us but the OP was trouble by the cost of importing liners. 

Upon further investigation I found that the cost of applying this would be around $5500 usd for an average in ground pool.

Not sure if this is the exact process the wifes uncle is using but is very similar. http://www.sandblast.net/?page_id=111  

[Harold Sukhbir]

Hi,

I've looked at fiberglass available in my country for AP use. The one used in the marine industry is not approved for potable water because of leaching chemicals.The approved ones are about 5-8 times the cost.

[steve]

Thanks for the tips!!  I found some interesting comparisons of different non toxic sealers here. It does not have the ISO resin, maybe too new, page is from 2004. I'm in a remote location so will look around for material availability. Wouldn't that ISO also be good for painting the lumber on growbeds? In the tropics I don't like to use much wood, especially around water. http://www.cement.org/decorative/Concrete%20Countertop%20Sealers.pdf  

[AlbertF]

it wasnt clear what you were painting/using.. you did say cement sealer but that doesnt neccessarily mean your growbeds are cement..  (could you use some kind of ferrocrete?)

i used the isothalpic (sp) resin on wood to make a 300 gallon fiberglass plywood fishtank.  pics of it here:

http://aquaponicsinparadise.com/APforums/index.php?topic=61.0

[steve]

Originally asking about sealing the ferro cement tanks. Later got ahead of myself on talking about growbeds.

AlbertF said:

it wasnt clear what you were painting/using.. you did say cement sealer but that doesnt neccessarily mean your growbeds are cement..  (could you use some kind of ferrocrete?)

i used the isothalpic (sp) resin on wood to make a 300 gallon fiberglass plywood fishtank.  pics of it here:

http://aquaponicsinparadise.com/APforums/index.php?topic=61.0

[David Waite]

Jim use pool paint. It is aquaculture and food safe. Hundreds of swimming pools and fish hatcheries use it to protect the concrete from decay and the fish from the concrete or lime in concrete.

[Chris Smith]

Pool paint may be used in hatchery's but it create a barrier to prevent leaching? The fish like a higher pH which is a result of leaching, but high pH will lock out nutrients to the plants and they will show signs of deficiencies shortly.

Paraffin will actually be absorbed into the concrete if you heat it with a heat gun after painting on. It is cheap and does not contain toxic chemicals or require special cleanup. No need for masks or gloves. It is widely available since it is a primary ingredient in candles. It is a by product of oil production and is more readily available in places that produce oil. Food grade paraffin can be purchased at a higher cost if you are worried about any impurities. Surf wax can be used in a pinch since it contains all food grade ingredients(because so many kids chew on it) but I do not recommend it since there are fragrances added.