Foamboard and Paint

I have finished first-coating the stands, and the lower ramps.  The upper ramps are almost completely second-coated.  See below:

 The paint is going on well enough, but I fear one gallon will not be sufficient once I get to the upper growbed.  The stands are extremely annoying with all their nooks and crannies.  But once painted, it will be done.  I am a bit concerned about the feet of the stands, and the lower slants.  For the former, the notion of water intrusion (as the porch gets wet during storms), and for the latter, I fear they'll "glue" themselves down to the floor after being there for 6 months.

I returned the two undamaged 1/2" foam panels to the home improvement store today, and procured two "blue board" foam sheets.  The key difference is: this foam board is extruded polystyrene (XPS), rather than the white expanded stuff I had purchased previously.  The foam is much denser, doesn't flake, and is reportedly waterproof.

I tried to get the store to order the 2" thick foam I needed, but to no avail.  It seems no one carries it.  I even tried looking for DWC suppliers, but again came up dry.  I'm really at a loss to know what people use, if they don't use completely inert Styrofoam.

Not all is lost, though.  I purchased enough XPS to experiment, and ordered a specific adhesive from the local box store's website.  The adhesive is called Eco-Bond, and reportedly (for the "Farm-Safe" variety) is completely non-toxic, hypo-allergenic, etc etc etc, no evil chemicals, no distillates, waterproof, etc etc etc.  Certifications abound.  Seems too good to be true, but we're gonna give it a try.  Worst-case, I'm out $13.  The goal will be to laminate two or three (or maybe even four) sheets of XPS together, to form a decent DWC raft.  I'm still undecided whether or not I should pre-drill or pre-mark the hole locations, and then glue around them, or else just clue the whole board with lots of beads of glue, and hope I got good enough coverage to avoid splitting during use.
 

Paintwork and Rafts

Painting

I have begun painting the various assemblies for the project.  I managed to find a good exterior-grade latex paint with low-VOC and relatively waterproof.  I'm putting two coats on for the serious wear-areas (any place that will be subject to the occasional water splash or mechanical interaction.

So far, I have only mostly completed the DWC tank.  It's one coat on the top-facing surfaces away from completion, and I will probably only double-coat the sections that won't otherwise be covered by or in contact with other materials.  Due to limited space on the porch, I'm playing musical-components in an attempt to avoid running out of room while painting and assembling.  Thus, the DWC is now sitting roughly where it will stay.

The color white was chosen arbitrarily....and partly to save time in the paint department.  To date, I've gone through nearly half of my one and only gallon.  The second coat does require less paint, luckily, and the GB will be less area to paint as well.  I must also paint the stands, the stabilizer boards, and the ramps for the DWC.  I have one coat on the GB ramps already (which I call "slants" in other posts).

Rafts

I was going to also cut apart some of my rafts today.  Then I made an unfortunate discovery.  The FAO manual mentions making sure that the polystyrene one uses for the rafts be of a food-grade (or food-safe) material.  OK, that makes sense, especially for the fishes.  I looked at the 2" thick sheet that I had already hacked up into a non-returnable state: contains flame retardant.  Fuck.

According to 365 Aquaponics, blue board insulation, or extruded polystyrene (XPS), is the best.  I had purchased expanded polystyrene, which is not recommended (it evidently disintegrates, among its other attributes).  I hope the blue board will also be sans chems, as others have reported that any chemicals within the polystyrene will leach out additives and these additives can be harmful to the fish (to say nothing about us humans).

I'm now going to engage in a brief search to locate possible sources of food-grade XPS.  I'm hoping that home-improvement stores will NOT be the only option.  If they are, I'll have to either find 2" stock or figure a way to adhere two or more thinner pieces together...while keeping it food-safe.  Fully cured polyurethane is one possible route, as (reportedly) once it's fully reacted it thereafter becomes inert and safe to handle.  It should also be waterproof.