Poly cover as raft liner

[Jovan Johnson]

Greetings All
Im in Jamaica and shipping the dura-schrim raft liner here is quite expensive however greenhouse poly cover is available locally, so could i use a double layer of the 6 mil poly cover and line the rafts?
thanks in advance  :)

[Wayne Hall]

Hi Jovan

 

I live in the Bahamas and like you have the same issues with cost. I was going to try using 6 mil polyethylene liner for the trough liners as this is the only thing that is available locally for me. Not sure how its going to work but hopefully it will be find.

 

[Nigel Clement]

Jovan, do you have a skybox. E Zone is a company offering freight forwarding services and I use them regularly to bring in my purchases. I've actually purchased dura skrimm about three days ago and I'm expecting it tomorrow or Monday. I also notices you speak about lining the rafts, did you mean lining the troughs?

[Two Jay]

We may be trying 6 mil gh poly for our troughs as well.  Cost and size are both issues for us.

 

[Nigel Clement]

I've seen a discussion, I believe on this forum, where persons may be using old billboard material as well.

[Harold Sukhbir]

Hi Jovan,

I'm using 12mm greenhouse poly(single layer)and its been in use for about one year so far with no problems. What you need is to fix it taught and not allow it to flap in the wind, this flapping reduces its life span. I also use as raft liner going on 8 months with no issues. I think you'll loose nitrification surface area with poly as its surface is smooth compared to Duraskirm liners, so i would figure in more liner surface area than the recommended standard ratios.

[Kate Mink]

Hi,

I'm in Hawaii and shipping here is also dreadful. I've used the 6 mil poly for tank (not trough) liner twice - once it lasted a year, once only a few weeks before leaking. I won't try that again!  It's uneven in quality, sometimes even within the same roll. My big concern with troughs, though, is that it degrades very quickly in the sun. If you use it, be ready to do a fast replacement at any time - also be sure your system design is such that an empty trough doesn't make a pump run dry, or allow your fish tank to drain.

[Jovan Johnson]

thanks all :D

as to Harolds Concerns would it make sense to put some pea gravel in the troughs for nitrification purposes?

PICS WILL ARRIVE SOON   :D

[Harold Sukhbir]

Hi Jovan,

I really don't think its a particularly huge concern but irregular surfaces do offer more suitable area for bacteria to populate rather than smooth ones. Gravel in troughs could turn out to be risky business at some point.

[Jovan Johnson]

i see what u mean

i guess installing a small gravel area out of a half 55 gallon drum would make more sense since it would also help filter out solids and can house worms. or jus do a integrated system. By the way im clearing the site saturday and installing troughs and fish tanks next saturday, so u can look out for it on my profile(ceteris paribus) :S 

[Kate Mink]

there are a lot of good systems out there with plenty of bacteria and no gravel, just smooth surfaces. As soon as you get any plants in, their roots will provide lots of surface area, too. Roots that look all clean and sterile are nonetheless totally filmed with organic compounds and bacteria - just as in the soil.

A recent Friendly Aquaponics newsletter warns against the use of worms that have been in compost that might have contained any animal manure. Deadly strains of E. coli can grow in the guts of warm-blooded animals (like cows), the contamination of crops like spinach with manure has killed people. It's not a problem with fish manure at all, they're cold-blooded and don't harbor those bad bacteria. So, if you want to run worms in your aqua system, get them from someone who's been doing that for a while.

[Harold Sukhbir]

Hi Kate,

Great points all!. Raft systems rely heavily on the presence of roots to provide the growing surface area for bacteria. So we have to ensure that raft are never without plants for too long and maintain proper plant rotation to provide adequate ammonia conversion.

If we maintain high water turnover, adequate oxygen levels, and close to neutral PH in our AP we can establish an environment which is not conducive for these gram negative bacteria to flourish and eventually so eliminate them altogether.

[Kate Mink]

True. I just don't think there's any margin for error with the virulent strains of E coli. Fortunately, it's easy to make aquaponics systems pretty much bulletproof on that. I love the fact that I never have to supplement anything except minerals, the fish do all the manuring i need.

Harold Sukhbir said:

Hi Kate,

Great points all!. Raft systems rely heavily on the presence of roots to provide the growing surface area for bacteria. So we have to ensure that raft are never without plants for too long and maintain proper plant rotation to provide adequate ammonia conversion.

If we maintain high water turnover, adequate oxygen levels, and close to neutral PH in our AP we can establish an environment which is not conducive for these gram negative bacteria to flourish and eventually so eliminate them altogether.