Backyard Aquaponics
A place to discuss aquaponics

Interesting. Perhaps if you want to avoid having to top water them so much early on, you might be able to use a bit of fabric or felt that will wick the water up sandwiched between the to pieces of foam. Then maybe you can just sprinkle the seeds in the little V cut at the top edge of the fabric.

I would have thought that the capillery action would have got enough water up to them in the early days.

+- 7 days and not caring for them...they the seed did their own thing...

Looks like the capillary action works with just the foam then.

Thanks for the feedback francois,

My efforts at raising seeds in the past have been next to hopeless. I shall give this a try, floating on top of my fish tank.
Should be good for baby spinach, sprouts and lettuce. Can then trasplant if I get the mood, or eat them as youngies.

cut and pasted of.................
yes this can be what's happening...when the word Capillary was mentioned you had me .......
Google and now I believe this is the process happening

I cleared 2 raft today to make space for new plants
took some lettuce and beans out.
the beans were doing very well but....space for basil and celery

this is a bigger system i want to build

more

THE SYSTEM CYCLE:
FROM THE CENTER OUTLET OF THE DAM THE WATER FLOWS GRAVITY INTO THE SOLID REMOVAL TANK.
FROM THE SOLID REMOVAL TANK THE WATER FLOWS GRAVITY INTO THE BIO/WORM FILTER
FROM THE BIO/WORM FILTER THE WATER FLOWS GRAVITY INTO THE GROW TRAY
FROM THE GROW TRAY THE WATER FLOWS GRAVITY INTO THE DUCWEED SUMP
FROM DUCKWEED SUMP THE WATER FLOWS GRAVITY INTO THE PUMP SUMP
FROM THE PUMP SUMP THE WATER IS PUMPED BACK INTO THE FISH DAM
THE PUMP WILL BE ON A TIMER OR LEVEL SWITCH

please advise...
what would not work and why not and what you will change to the system
thanks

Hum,
Depends on how much you are wanting to grow duckweed. I would probably place duckweed right after the solids filter if wanting to get the most duckweed possible since duckweed likes to use ammonia directly if it can.
If the duckweed is just a throw in, then you can leave it where ever you like.

What are you going to use for the media in the Bio/worm filter?

How about an exploded view of the sump where the pump is? It it looks small since everything else is flowing by gravity toward it, hopefully you've planned an automatic top up valve or you'll be doing a lot of manual top ups because of evaporation and transpiration. I haven't really thought through how an automatic top up and a pump with level switch can coexist in the same location, can they work together or would you wind up with one or the other always running? I know you can do this with Constant Flood because you don't need a float switch and actually this whole system would work CF pretty well. Wouldn't really be CF if you put the pump on a timer but short periods without flow should be OK, especially if you're aerating some other way too.

I would say the system should run constantly. Raft beds like a continuous flow of water and I don't like float switches to control pumps.
But that is just me.

As to a top up valve, you could just have to make sure that there is space between the normal low water level and the pump sucking air level to install a float valve so that I can add water to the system well before the pump starts sucking air.

To have a float switch involved would just mean you set it to turn on the pump before the sump overflows and turn off the pump before the normal low water level but that could get tricky with a top up valve involved and float switches are so easily fouled or failure prone that I don't like to use them.

Hi TC
I have always had the approach that duckweed is my last line of defence before water back to fish?????

OOOOOOps forgot to mention ...the system will flood and drain via 3 bell siphons at the end of the grow bed??
questionI don't know if this is possible using 2 or 3 siphons????? to empty 1 grow bed... not what I would use I believe in keeping it simple constant flow
I have never used a flood and drain with bell siphon....my first system was constant flow and the system I have now is the same very simple no problems, no indexing valves, nothing fancy...runs 27/7 with minimal problems and cost. The grow beds in this system will be filled with media...20mmm washed quarry stone. The pipe work will all be Ø50 mm and the system will be designed to add more pipes in places needed it be????My approach is that management will tell you what you change and improve....I think any system will give different result with different management.....management the critical factor... Oooops i told a lie, this system is not for me but more somebody else's idea ...he approached me with his idea. His grow bed size, the length and depth, the area covered was the constrains of the design....
not any more info...I designed around his idea but I also don't want him to fail?????
not the way I would do but he is adamant, but I think with one or 2 changes you can make it work
2007/8 he came and viewed my pilot system and today still humming and thinking about the idea....
never grown fish before and needs to make money from day 1?????
i needed your input and thanks