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

[TCLynx]

Only question I had with using paraffin was.... are there any bacteria that are likely to eat it away over time?  I guess it probably doesn't matter too much since by then the concrete should have cured for quite some time and the bioslime would also reduce leaching but I wondered anyway.

 

[Chris Smith]

My concrete tanks have been in opperation with paraffin now for a year with no issues. The water still beads off just fine. There is a layer of bio slime covering the paraffin but there does not seem to be any deterioration or loss.

[TCLynx]

As I say, I do like the idea of paraffin seeing as it is easily available and generally food safe (heck they use it in chocolates and used to use it to seal up jam jars.)  Paraffin dips are also used as a treatment for arthritis and to help make your skin soft.

[ericjf7]

Sorry to have missed out on the discussion, I wasn't anticipating any serious problems with bare (aged) concrete once the water is changed a few times -- I suspect there are similar discussions within the site, is there a simple  way to reference them?  Some pics of my new tanks are in my photos.

[ericjf7]

Three paragraphs of input disappeared at the click of a mouse!   Guess I'm a concrete guy, not a techie!

 

To summarize, I would be leery of any surface application which wasn't designed to be penetrating, particularly if there is any residual moisture in the concrete itself - in this case it may be best to use water based acrylic or epoxy products specifically designed for the application. Additives such as Xypex are designed to  be added to the mix at the time of construction, or applied as a parging mix to the finished product, are waterproofing agents used in municipal drinking water reservoirs , and become impervious - however it is difficult to get a smooth finish with the parging.

 

Properly cured concrete, kept continuously wet for thirty days at the time of construction would be more impervious  to leaching as well as less prone to cracking, avoiding problems later. A mild acid wash may help, my guess would be, several water changes before adding fish should do the trick.

[Michelle Silva]

Chris, that is awesome..love that. What is the size tank that you did? Do you have a good source for the wax that you could recommend and the approx cost?

Chris Smith said:

I used paraffin wax. I warmed it and painted it on. Then I used a propane torch to heat it so that it melted into the concrete. I added a second coat after that. The water beads off the concrete now and there is no more leaching.

[Michelle Silva]

woohoo!

Chris Smith said:

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.

[Michelle Silva]

Do you know how paraffin wax is in terms of safety, ease in application, cost compared to beeswax?

Chris Smith said:

I used paraffin wax. I warmed it and painted it on. Then I used a propane torch to heat it so that it melted into the concrete. I added a second coat after that. The water beads off the concrete now and there is no more leaching.

[Michelle Silva]

I didn't know much about paraffin, just found this .

http://www.britannica.com/EBchecked/topic/442604/paraffin-wax

Chris Smith said:

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.

[Stuart Polkinghorne]