Backyard Aquaponics
A place to discuss aquaponics

Collum - thanks for the info on the plug hole covers, I'll try without first.

Dave - The grow type plugs would be great but I'll probably use volcanic rock since it's cheap and re-useable out here. Hadn't thought of Grow Grips..



Thanks for the info on floating the raft.

I think this is what I'll do although I'm thinking spa jets which are based on the venturi principle. I'm either going to have to up size the pump I have (which I'd have to do anyway just to pump out to the DWC) or use a second pump on a timer. The question really becomes how many jets or bakki showers would I need. While the bakki showers would be easier, I rarely need the cooling effect they create so I'm thinking these aren't the best method for me.

MW, good question regarding the pump size. If all else fails with suspending the rafts over the trough and spa jets, I'll be heading that way so it's good to know.

Cheers

Collum, I noticed in another thread you had some uniseal problems. Was this on a DWC bed and are there any pictures. I'm planning on using Uniseals for the DWC but haven't decided which side to come through (thinking top down) but read about your problem of the ground pushing the uniseal out. Suggestions are welcome.

Thought this paper had some interesting information - http://ag.arizona.edu/ceac/sites/ag.arizona.edu.ceac/files/Deep%20flow%20hydroponics%20merle%20jensen.pdf

Observations from my DWCs.
1. 1 1/2 is fine providing your pots don’t sit to far into the water,saturating your media,just touching with young plants is good,an air gap with established plants is better,I use 2 inch poly this has my pots just touching the water surface as the roots come through these pots go into floats with a 1/2 inch spacer as part of the float.
2. I leave empty pots in the holes to give the mosses less places to lay there eggs.
3. Media is important,to heavy and if you have to lift the float with media and established plants it could cause a problem,cracking breaking etc,i Trailed a float with the pots filled with small washed river gravel,surprising even in my small pots how much extra weight this was,i am currently trying the pot a third full of gravel,then as the roots come through the sponge just placing it on top of the gravel,anyway how often do you need to lift a float ?
4. Without an air gap you will need extra oxygenation,how about simple airlifts,very good oxygenation can be achieved from a small air pump,i want to try these in mine.
5.Here in Thailand the hydro guys growing lettuce and leafy greens just use the one inch foam cube in a inch hole in one inch poly float,as the plant grows so it grips tighter in the hole thus supporting it.
6. If you are using the same water in your DWC as you are in your media beds to many flowing plants will rob the system of nutrients,not giving you the growth you would like in the DWC.

It was the DWC beds that failed, I don't think the media beds would have the problem, the gravel weighs it down.

If the uniseal has enough bite, they should be pretty safe, I don't think mine had enough bite. I tried to route back the hole for the uniseal, but it might not be strong enough, and with slight moisture, or the ground below moving, or the bed sinking slightly.

It's easy enough to fix, just involved me pulling the bed apart and stuffing around with it. Draining the DWC again, pulling back all the pond liner, and stuffing around with it...

I'm not great at paint, but this should give you an idea of how to make it work:


It's also gives you the ability to move the bed around slightly if your pipes are buried like mine. My GB's are frickening heavy. And when the bed is in place, and the pipes don't line up perfectly (even out by 3cm will throw it out), you end up with weird angles, and way too much glue to stop it from leaking, and when the bed starts sinking, and you need to move the whole thing to reinforce the legs, it's very hard to move 2 tonnes to the exact same position.

I can take a few photos of mine if you want, it's nothing special though, just a uniseal going through a piece of wood.

Makes sense Collum. I'm not sure if I'll apply this to my setup, I have some thick acrylic that should work without the extra support and I have to line up the pipe underneath anyway (or there are going to be problems). I'll have to think about it before I do any drilling to set these up. Thanks.

Dasboot, thanks, I'll have to take along one of the net pots and hold it up against the raft to figure which has the best depth for doing the floating version. As with most things 1" isn't really an inch anymore so hard to say without comparing directly. The DWC will be fed by the RAS system I just finished and will only have one media bed from an IBC and a couple of small trees hooked in (but they won't get the flow any sooner than the DWC). I was thinking about using scoria but it sounds like hydroton might be better or just partially filling the cups to keep the weight down if I have to float the plants instead of using an air gap.

Fed from the RAS should be perfect,here is a couple of pics to show how i configure my floats,my starter float has no spacer then as the roots push through they are moved on to a raft with a spacer,this gives a air gap of half an inch to the water surface.

Interesting way to do it Dasboot. I'm thinking along similar lines but in order to avoid having to do the spacer, I'll start plants in net cups outside of the system then transfer them to a raft suspended over the water. I'm thinking of using 1020 propagation trays like this http://www.novoselenterprises.com/products/single.asp?ID=725602C

I'm not sure that tray is the exact one but the idea is to set the 2" net cups into the propagation tray and have this sitting in water that comes part way up the net cup (probably using an old ebb and flow tray I have). I'll let the roots get started and then shift them to the raft beds rather than give up raft space to seedlings and starts.

Hope that explanation makes sense. I think this will work and allow me to heat the water to get the seedlings and starts off well.

I like the air channels in your rafts, did you add those or did they come that way?

That should work ok,my foam cubes are done in a similar way,once they have germinated they are just floated on water supported in a tray with a mesh base,then as the roots come through they are place in a starter float with the spacings close together,then as they start crowding they are moved to a float with wider spacings and a spacer to lift the pot from the water.
The slots were put in with a piece of 3/4 plastic pipe with 80 grit emery cloth wrapped around it,then just sanded them in,as i got to depth if i took it steady i could get a smooth finish.

Looks very well done but sounds like it would be tough going to get it done. Thanks for the feedback on my plant starting idea.