Comment

Comment by Francois Lemmer on February 27, 2011 at 7:47am

My system was gravity fed and my electricity was min.

 
Going to bigger systems there is a must for min cost.

My 0.75 kW pool pump pumped in cycles of...

My dam had a centre outlet and a ball valve that would close as a water level reached a certain level.


The valve was there for emergencies (power breaks).

From my dam the water flowed with gravity directly into my grow trays. (500mm lower)
In this Ø50 mm water line from the dam I had a tap to control the flow into my grow trays.
Very useful always have this setting tool in the out flow line available flexibility.
After the tap in the water line I split my pipes into 8 x Ø50 mm outflows into my grow trays.
This is also where I would add my makeup water into system allowing a very slow constant adjustable feeding back into to the system.
This also helped as a breather. On the far end of this pipe I had to add another breather and that was how I got my flow equal to each grow tray. And I had a tap for maintenance access to cleaning pipes easy.


The other tap was also for maintenance/direct from dam outlet.


In my grow trays I ended up with 25+mm stones.
From my grow trays my water flowed through the grow beds and into my duckweed dam that was a level lower. (800 mm)
From my duckweed sump into a 210 litre drum sunken into the ground.
This gave me the advantage of having an extra level.
This was my pump sump and using a level control in this sump I circulated my water back to the dam under pumping pressure in cycles of 10 min of and 18 min pumping. (Piping from pump to dam Ø40 mm)
Pipes from grow trays into duckweed sump and into pump sump Ø50 mm pipes

.........free..... Oxygen.

So in short my water flow through my system had 19 let’s call them waterfalls and using the pumping of the water under pressure.... from my thinking solved part of oxygen problems in my system.
In the water line from my pump.
I had a tap and a y split of the water. The water into the dam stayed in Ø40 pies but on the end I blocked it off and drilled some 2 mm holes. In this section of pipe I y split again into hosepipe diameter and this was used to circulate the dam water anticlockwise in my dam.


At the bottom split to normal hose fitting this water went to my makeup tank which was a 210 l blue plastic drum. From this drum gravity kicked in once again and running this water back into the system line after the tap and before entering the system.


OPTION 1 24 HR. CYCLE CONSTAND FLOW
KEEP WATER IN DAM TO KEEP BALL VALVE OPEN ALWAYS
THE VALVE USED FOR SAFETY FOR POWER BREAK/

OPTION 2 FLOOD DRAIN CYCLE
WATER LEVEL MUST BE MAINTAINED IN DAM
OUTFLOW CYCLE 10 MIN
PUMP CYCLE +-17 MINS
THE SYSTEM SEQ. WILL BE.......
1 PUMP STOPPED / DAM FULL / BALL VALVE OPEN
2 PUMP OFF / WATER LEVEL IN DAM DROPS / WATER RUNNING INTO GROW TRAYS
3 PUMP OFF / WATER LEVEL DROPS AND BALL VALVE CLOSES IN DAM
4 PUMP OFF / VALVE CLOSED IN DAM / THE WATER VOLUME IN MY GROWTRAYS THEN RUN TO
MY DUCKWEED / PUMP SUMP
5 RISING LEVELS IN MY PUMP SUMP START THE PUMPING (CYCLE) BACK INTO DAM
6 PUMP PUMPING / DAM FILLING / BALL VALVE CLOSED
7 PUMP PUMPING / DAM FILLING / BALL VALVE OPENS
8 PUMP STOPPED / DAM FULL / BALL VALVE OPEN
9 PUMP OFF / WATER LEVEL IN DAM DROPS / WATER RUNNING INTO GROW TRAYS
.............. HOPE THIS EXPLAINS WORKED WELL AND EASY TO RUN AND MAINTAIN

In my system if 100 mm WATER LEVEL DROP’s IN DAM THAT WOULD = 1500 litres (water out of dam)
My dam water level dropped +-70 mm ... so the pumping cycle of water into dam = 17 min. = 1050 litres water back up to level. (Very simple but to me close enough.)
Pump pumps for +-17 min. To replace water in dam