Sunday, 21 October 2012

The Flood and Drain Timing

I didn't do much on my system last weekend. As you might already know, my plants are not doing very well....yet. So I decided to experiment with the flood and drain timing. Since my current setup is using the pump at minimum setting, my maximum timing is fixed at about a minute or so. From my last post, I've shown how I increased the timing by drilling tiny holes on the pump outlet pipe. I managed to get 2.5 minutes out of that.

So last weekend I make the holes a bit bigger and manages to get 4 minutes for flood and drain, about 50 seconds of that is the drain cycle. Not satisfied, I drilled 2 new holes using a 5mm drill bit and the inevitable happened. The syphon action didn't happen and the equilibrium flow is achieved. This is not good. From this experience I learned that to get a positive syphon kicking in every time, the water rate flowing in must ALWAYS be more than the water rate flowing out. Otherwise the water will just flow continuously from the the stand pipe without the syphon action.

I was lucky because my pump has the variable flow setting. So I increased the flow rate to about a quarter and the syphon is back in action again. This time I get 1 minute for drain and 6 minutes for flood, a total of 7 minutes duty cycle. I just leave it at that for now and see how the plants doing in the next couple of weeks.

I also forgot to mention that I sown 4 pak choys and 4 lettuces in a soil in a separate seeding pot last week. The pak choys are already sprouting but not the lettuces. So I did a bit of googling and found that lettuce will have small to no chances at all to grow at temperature above 27 degree Celsius. At 27C, it will flower faster so less leafy. Ideal temperature would be from 22 to 25C. As from my previous post, the ambient temperature around my grow bed at noon is about 34C! So it is not going to happen. I was thinking probably I can grow lettuce inside my house where it is colder or wait for monsoon season where temperature will drop to between 24 to 30C. I'm sceptical that it will grow but I'm going to try anyway when the time is right.

Sorry no picture this time folks!

UPDATE: Last night I heard the water flowing continuously into the fish tank. So I checked it in the morning and found that the water is flowing in equilibrium again. It seems that the water inlet flow rate is slower than before. I don't have time to check why, so I just increased the pump flow rate a bit and the problem is gone. Will check it again tonight.

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