Polystyrene floats in DWC

[Josie]

I love Aquaponics but have yet to start my own set up. I'm still trying to fill in my knowledge gaps.

I am concerned about Styrene leaching into food from Polystyrene floats used in DWC, Anyone know anything that will stop me being concerned? Everyone seems to think it's only a matter of time before Aquaponically grown food is classed as organic but this will not be the case for DWC using Polystyrene floats.

Hope someone Knows more than me (should be easy!)

 

 

 

[TCLynx]

Now we all have to keep an eye on your rafts for several years to see how your experiment mixture turns out Vlad.

Let us know what % mixture you finally decide on.

[David]

I've opted to forego the painting myself as I've not had sufficient time to research it further. But hopefully I won't have to wait a few years before making a decision.

[Vlad Jovanovic]

@TC...Yeah, I'll be keeping an eye on them too. And I'll let everyone know what % mixture I use and why (might not be the best ratio for everyone in every situation...heck, it might even not be the "best" for me in my situation, but I can surely at least explain the what/how/why behind my decision if anyone cares to know)...

@David...Just don't take too long deciding :) The rafts that I've been using since this past Oct/Nov have already started to be affected by the suns UV rays. (They've been exposed pretty constantly since then). All exposed surfaces have 'yellowed' a bit and if I run (scrape) my fingernail down them, a chalking fine dust falls off. The portions of polystyrene that were blocked off even with duct-tape are fine underneath the tape.

I was surprised how quickly the UV light compromised the surface of the raft material. I 'thought' it would take a good while longer. Polystyrene is not real cheap, and I don't want to spend another $500-600 on replacements all that soon...Not too mention the PITA of drilling out all those holes...There may or may not be better options available to you than what I'm going with (UV resistant polyurethane resin, UV resistant film that you could lay over the rafts, etc..?), but at any rate it seems worthwhile to protect your investment and avoid all that polystyrene dust falling into everything...

[TCLynx]

I've never really used the normal Rafts with holes type thing.  What I have used, I'm simply covering the polystyrene board with capillary matting or wicking mats and I set my seedling trays on that.  The mat protects the foam and the foam supports the mat and the mat wicks the moisture to the seed starting media.

I've thought about perhaps laying the mylar over the foam and just cutting an x at the plant holes.  I wonder how well the cheap mylar emergency blankets hold up out in the sun?  I've only used them indoors around grow lights and stuff as curtains.   Of course if your rafts were that shiny, you would really need sunglasses to work in the system.  I have enough problems with the glare off the white liner and towers giving me a headache.

[Vlad Jovanovic]

Yeah, I bet the glare off of those things can get pretty intense...See if you can get Nate to make you some in a nice soothing green hehe...

I thought about different materials to line the rafts, but most of it is more expensive/hassle here that the paint (with the exception of maybe tin foil)...

I'm usually not a big fan of wikipedia, but boy-oh-boy could I have saved myself a bunch of 'snooping' with this "latex-acrylic" thing...turns out that "Latex paint" never had any latex in it, it was always vinyl, PVA, or acrylic/acrylic co-polymer. With the most expensive and top quality "Latex Exterior paints" always having used 100% acrylic...From as far back as they were invented/existed. I wonder how the hell it got to be called "latex paint" in the US to begin with.

What a releif...now just to come up with a ratio that will get me what I need for the least amount of money (or close enough for hand grenades...though I'd rather err on the side of quality with this one)...

Man, building this AP-GH in Serbia has been one phenomenally monstrous pain in the ass that just never seems to end...talk about headaches...sheesh

[Jon Parr]

How about epoxy? Make your rafts into surfboards. Some white (or pale yellow) pigment thrown in would make them colorfast, and epoxy adheres excellent to EPS. When Clark Foam quit making foam surfboard blanks a few years ago (gosh I think it's been more like 15 yrs ago), it left shapers here scrambling for an alternative. EPS and epoxy was the answer, and produced some stronger/lighter boards than the old Clark/polyester method, and apparently easier on the environment. I can get epoxy here for $30/gal, and the added strength would let you get away with thinner/cheaper Blue Board, and the things would last forever.

[Vlad Jovanovic]

Crap Jon, that's a whole 'nother can-o-worms...I suppose if one could find epoxy resin that is devoid of TBBPA (tertrabromobisphenol-A) it might be worth a shot... I'm not saying it will leach or is dangerous in that sort of app, just that people may want to avoid it (til more can be known) for the same reason the HBCD flame retardants might be smart to avoid in foam-core. 

Speaking of which, did you ever check with Beaver Plastics on that one? There may be some folks in the US who would be interested to hear what pans out...Turns out you all may have some funky regulations regarding construction grade foam core in the US...necessitating the need for flame retardant additives to be used in all foam core...and HBCD (hexabromocyclododecane) is still the cheapest to use...and in the fine and long-standing tradition of US Corporate denial concerning health hazards/issues (particularly if a bit of profit is at stake), Canada's Beaver Plastics may provide just the alternative that raft seeking-health-conscious-american-aquapons-who-give-a-flying-fuck may want/need to know about...

[David]

I started noticing the boards turning pale blue on their way to another color.  That's quick (a month) but the sun is apparently bigger here in Texas.  I applied one light coat of Kilz water based exterior on the topsides to help keep them from deteriorating. I will be looking at the surfboard option mentioned previously but using epoxy paint instead. 

As and aside, there is a saltwater bait shop near here that has success using epoxy paint for reinforced wooden tanks and he builds 4 x 4 x 8 with integrated fingerling/bait tanks for about $400 delivered.  The only downside is that they are not easily moveable without forklift,crane,ufo technology etc etc.  He mentioned sealing the DBB with epoxy paint which is where I got the idea.

[Norm Eldreth]

I have found a great source from White Cap Construction Material, they have many locations in the US, as of today in Charlotte NC it is $38 a sheet for 4x8 2" board.  The blue box store wanted $48 and had to order, my guess they were waiting on White Cap to deliver to them.

Miles Perryman said:

What thickness is most common in DWC raft system? 2" ? and how do I get the Blue Board, Lowes and HD dont carry over 1" thickness.

[TCLynx]

Don't bother with 2" foam.  It costs twice as much AND you have to go to more extreme lengths to get good holes in it.

UVI uses 1" foam and it works just fine and if you do a 1 7/8" hole it will be enough smaller than the 2" net pot that you don't have to worry about the net pot starting to fall through as the hole wears and it sticks up above the surface of the foam so it is easier to pull out anyway.

Look up insulation suppliers in your area and start phoning them up to see if they carry 1" dow blueboard.  I expect you will find it for closer to $20 a sheet.  Tip, I actually like the score board since it makes it easy to break the boards into 16" wide pieces which is a convenient for me to lift up when full of lettuce.

[marie]

Jon Parr said:

How about epoxy? Make your rafts into surfboards. Some white (or pale yellow) pigment thrown in would make them colorfast, and epoxy adheres excellent to EPS. When Clark Foam quit making foam surfboard blanks a few years ago (gosh I think it's been more like 15 yrs ago), it left shapers here scrambling for an alternative. EPS and epoxy was the answer, and produced some stronger/lighter boards than the old Clark/polyester method, and apparently easier on the environment. I can get epoxy here for $30/gal, and the added strength would let you get away with thinner/cheaper Blue Board, and the things would last forever.

Hi Jon, are you talking about fiberglass? Like they use on boats and vehicles or something else. marie

[Jon Parr]

Not exactly, Marie, but close. Boats and old surfboards uses polyester resin and fiberglass matting for strength and waterproofing. However, the new surfboards are made from a different foam (now EPS), and the polyester resin melts the EPS. So, we use epoxy now in place of resin, and it is superior in every way. It is stronger, more predictable working time, and doesn't leach. I have considered coating my EPS rafts with it, but they are pretty sturdy and paint seams to do the trick to block UV. I paint mine light brown, to break the god-awful glare of white rafts.