Floating raft bed alternatives

[Juniper Rivers]

Hello friends,

 

I am trying to find an alternative to polystyrene floating raft beds and am curious if anybody on here can point me in the right direction.  I remember seeing a youtube video months ago where some people were using raft beds that appeared to be made out of plastic and fit together almost like a puzzle in an interlocking fashion.  These seem ideal and I would love to find some for a closer inspection.   Any information or help would be greatly appreciated.  Thanks!

[Chris Carr]

Glen Martinez uses plywood for this. Cheap, renewable, long'ish lasting and easily paintable. Since it is thin, you also get good exposure and circulation around the net cups with the humid air.

[TCLynx]

If you use boards, you simply make them big enough to support on the edges of the trough.  They have to be thick enough/strong enough to support across the span and not sag too much when heavy plants grow large.

Then again another option might be to do rafts with "pontoons" to provide some air space.  However I've found that such things tend to sink down as the plants get bigger/heavier and so the problem is when the plants are small, they don't touch the water and need wicks or top watering and as the plants grow the whole thing tends to sink down until it is essentially covering the water surface again.  So far I haven't found a easy way to deal with this.

[Ron]

 Yes keeping the material light and keeping the work as easy on my back and joints as possible!  If the water level is high could the trays be supported by a frame?that hangs on the edge of the tank?

   Along with that is how deep is your water?i first considered a film method,but im trying to avoid powering bigger pumps running 24/7. So smaller dc  pumps that just keep the water slowly flowing in shallow tanks is what im thinking of. I havent found any good tray and shallow tank combos for sale(think smokin deal),i keep looking around.

[Chris Carr]

Great point on high value real estate and not wanting huge walkways too and of course considering which method to employ would be situational for sure. I was more referring to Vlad testing it out on his system before making a larger change. I agree as well one large issue is harvesting from one side of the raft and getting it out of the system. With some creative thinking that should be easily enough to overcome.

For example if you are already committed to two people to lift a raft anyway, and the rafts were on the ground then a frame on wheels that straddles the trough to raise a tray at a time to a comfortable working height would effective.

[TCLynx]

More water is more temperature stable, especially if you are not pumping continuously.

Don't make it more complex trying to use some sort of frame to suspend the trays down below the rim of the DWC trough.  Plumb it with big plumbing so you can set the water height with minimal fluctuation and use bigger net pots so the bottoms of the net pots can reach down to the water and just place the boards on the rim of the trough and then hook that to a separate sump tank with top up valve to make sure the water level doesn't drop too low or rise too high.

I've seen people do something like this using mortar tubs like they sell at lowes or home depot though I think they are kinda shallow for most aquaponics but they work ok for small stuff.  Tip, you have to support the sides of the mortar tubs some because they will start to bow out over time full of water and or gravel.

[Vlad Jovanovic]

Ron, with extruded polystyrene, there are no "small beads that (could come) off"...you might be thinking of expanded polystyrene...anyways...

Yeah the whole assembly line thing is hardly an absolute requirement...but greenhouse space is premium real-estate, so it might help to have seeding tables, nursery troughs etc...at one end and a 'harvest station' at the other. You can do some of this stuff outside when it's nice out, but when the weather is crappy it sure seems good to be able to do it in the GH...

Also, lifting up rafts and moving them around (carrying) them above other plants tends to drip quite a bit of water on the plants below...wet leaves are something I try to avoid (without using some sort of anti-fungal agent...worm tea, potassium bi-carb etc...Almost all fungal diseases that I know of with the exception of powdery mildew require free water on a leaf surface to take hold and infect, so I'm a real faciast about not getting leaves un-unnecessarilly wet . Harvesting at one end avoids this little quirk of mine. I suppose if you had a huge expanse of space to work with this kind of thing wouldn't be a problem, but my GH is only 2100+ sq.feet...there's enough space to comfortably walk between the troughs, but using that space as a "mobile harvest station" is out of the question unfortunately.

The money I'd spend on the materials to make rails/rollers is about in line with what air pump(s), PVC air lines mains, the 1/4" tubing that goes from the header to the air stones, the plastic nipples that connect them etc would cost...not to mention the electricity...I'm pretty sure that this is one of those things that I actually will end up doing, but I've just got too much on my plate right now to fabricate all that stuff at the moment...Maybe by spring before DO actually becomes a big problem...

[Ron]

  I had imagined the tank for the fish being rather large but what the trays are on being shallow. Otherwise you sound about right.I thought about stock tanks for the fish,or something similar.This is all part of looking around here for ideas on tanks and trays. 

 

[Vlad Jovanovic]

Ron, I've posted this elsewhere on this site, but you might get some ideas from this very interesting man and his work ...http://www.ctahr.hawaii.edu/hawaii/downloads/Three_Non-circulating_...

[TCLynx]

Ron, it all depends on the scale you are dealing with and the goals of the system as well as the climate you are trying to do it in.

[Ron]

  Vlad i checked that out.It reminds me of what i did in the past.Im going to avoid the pricey chemicals and go with fish this time.Thanks for the good info though.

TC,your right.Ill just keep reading the many articles here.

[TCLynx]

Yep lots of research.  But don't let it stop you from getting started in a small way and learning a little hands on while you keep researching the "bigger system".  Because Aquaponics is addictive and there always seems to be a next system.

And that paper you posted the link to Vlad, it has me thinking, dangerous.  Good article though.

[Vlad Jovanovic]

Um...Ron, the point wasn't plant nutrient source, I figured you'd ignore all that, as well as the non-recirculating part, but rather sub system methodology and potential construction...

You don't really think that the flood and drain media bed method was invented for and by AP do ya? Or that either DWC raft, or NFT came out of aquaponics? Those are all old hydroponic techniques adopted to AP. These (the raceway techniques anyways) are just some more that can potentially be modified and be put into practice in an AP setting by someone who wanted to avoid some "carved in AP stone" stuff that currently most everybody uses/does. (Like say, use polystyrene, or a raft system that has to float, or air stones in the troughs etc)...

Yeah, lots and lots of research (and then trying to figure out how to modify those tidbits to suit your AP purpose/goals, set and setting)...Waste water treatment papers for the bacteria, RAS for the fish, hydroponic literature for the plants...all of those areas are goldmines of AP related info.