Backyard Aquaponics
A place to discuss aquaponics

I am working on a design for a seed starting chamber. I spend way too much time babysitting my starts in the spring. They are too cold, too hot, too wet or too dry. This will be a natural light setup attached to the widow from house to GH. Here is a pic of the window from inside.



From outside



Here is a basic sketch of what I have in mind.



The heat tape is Flexwatt. It comes in 11 in rolls sold by the ft. There is a +/- clamp with teeth that go to each side of the tape. It is plugged into a thermostat with a soil temp prob to set temp range. Regular 1020's trays with saran wrap or clear domes for germination. This is what reptile breeders use on their breeding racks under tanks.

The 2 troughs will be 1/4 luan bottom with 1x2 sides lined with EPDM. I have most of the scraps for this but it only allows 1 1/2 in of water until over flow. I am figuring a 1/2 to 1 in of water flow. Water will pump up from a container inside through window opening to the bucket with siphon outside. I want to drain everything back inside at night to keep water warm.

The GH will keep it warm during the day. At night I can open the windows to regulate heat. The sides of the box will be foam for insulating. The front will have a plastic curtain to hold in humidity.


Things I need to figure out.

1) Will a 1 1/2 side be enough to get good watering at 1/2 to 1 in deep.
2) Media...rock wool, coarse sand, foam, sand/penlite/peat mix. Starts will go into AP and dirt.
3) Getting too hot. Possibly a fan/thermostat blowing inside the house to draw cool air through box

A couple of suggestions you may or may not want to think about RairdogAP -

Sounds like the bottom support will be provided mostly by shelving or the insulation because you won't get much from the 1/4 inch Luan (it's known for it's bend-ability). I'd be tempted to skip the Luan and just have some sort of hanger around the edge of the EPDM to raise the sides and just clamp it in place. Dave Donley's threads might give you some ideas if you are interested in trying something like this.

Another option, if you have a safe way to saw, you could just take some plastic rain gutter and rip it in half lengthwise and cut to length for the sides of you troughs. Then drill through and use cable ties or just use mini clamps to attach in position on the some wire shelves. Basically just making a rectangular frame where EPDM bottom would just rest on the wire shelving. Might not look as good as you want but would be enough to support the EPDM and would be inexpensive.

Cheers

I'd be concerned about the constant-immersion of seedlings... what kind of media will you use? If sticking with peat pellets, they'll damp-off for sure. Like rockwool, they retain a ton of water and shouldn't be in standing water but watered as needed. Might be possible with perlite? Or run the pump once a day for a minute or less, depending on how they wick it up? Though that changes quickly with seedling growth.

Scotty, I planned on using wire shelves for support/adjustable/removable.

Ben, I am still working on the media and trying to get away from peat. I'm leaning towards a coarse sand/vermiculite mix. Rock wool is to expensive and wasteful. Most seedlings will be for dirt but the greens. The pump will only run for a few minutes in the morning and then maybe around noon. I just need some way to keep them from drying out until I get home in the afternoon.

This topic really needs more attention. If you live in a warm climate seed starting is not and issue. There are lots of us in the colder climates that struggle with starting seeds and keeping the proper watering and heat requirements. If we don't get a proper start before the warm weather arrives it can lead to a smaller harvest. We end up losing starts and resorting to buying them. The local greenhouses have it down to a science with controlled heat and watering but we end up with undesirable ferts and chemicals that are not good for fish. We also spend way to much time rinsing roots for transplanting and deal with the shock.

Hydroponics have it down to a science. Why can't we?

Unfortunately, they do. They use rockwool. Like you said, they are wasteful. I guess I just don't mind rinsing roots.

Rinsing isn't that bad. It's more of a heat/watering problem which is why this project started. Peat/soiless mixtures are easy to come buy and can be dumped in the garden or compost. Dampening off poses a problem sometimes.

For the media I'm picturing small biodegradable bags like what holds the peat pellets filled with smaller hydroton or expanded shale. Something that can be broken apart and re-used at the end of the plants cycle or anytime. Easier rinsing and not detrimental to the system.

The first components of the proposed system have arrived. It is pretty economical for a 6 foot heat mat compared to several heat mats. The Flewatt heat mat is sold by the ft. You simply crimp a connector to each side and plug it into a heat controlled thermostat which can be set to desired temp. A 6 ft strip will heat 3 - 1020 trays.



The temp probe which is under the green tape can be placed under the trays or directly into the soil. Set it at 80 deg or desired temp and it is done. This is a proven system that has been used by reptile breeders for years.

I have a 4 tray seed starter but haven't tried it with water (as opposed to soil) in the 1020 trays so far. I've been starting the seeds in seedling mix and then transferring either to the wicking beds or AP. Now having DWC channels, I might try it with the heater below 1020 trays (with water in the bottom), with 2" net pot holders (using scoria for the DWC). I'll probably use a smart valve (from an autopot) for the water level control. Not sure if this is a legitimate use of these tray heaters but it shouldn't take much water for wicking once the seeds have started growing.

Plan B is to use an old flood and drain tray to grow the seedlings and just warm the water going into the tray. Don't know exactly how this would work yet though.

Scootty, I'm trying to avoid heaters under water trays. The top rack will be heated to 80f for spouting. With domes there is little water needed. The bottom trays will have water stored inside so it should stay around 70.

I am now leaning towards using Ultrasorb for the media. It's basically 100% DE granules used for cat litter or oil absorbent. I have been reading about the HP guys using it. It has great wicking power and is ph neutral. Side by experiments (tomatoville) against jiffy mixes(peat/perlite) showed better root development, rinsed easier and less damaged roots. There was also less dampening off. There is no organic matter to grow the bad stuff and is widely used as a topping to prevent dampening off. It can be reused and sterilized in the oven.

I like the idea of using Ultrasorb. Anything to keep slugs and snails out

Interesting and cheap...

I planted some cool weather greens in Optisorb today. 14 bucks for a 25 lb bag at Fastenal. It is a coarser grade than the Ultrasorb. I filled the 1020 trays and added 8 cups of water. The water wicks to the top and turns the media dark. Light weight and easy media to work with planting seeds.

Any observations on the pH using the Optisorb Rairdog? Maybe just check the pH of any excess water in the tray after 24 hours vs the pH when it's added.

Just a couple of comments

Normally a heat mat would be at the bottom (heated air rises)

A sealed container to water the seedlings with either a wicking mat or straight water filled tray (saves pumping)