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Category: Aquaponics | Posted: Sat Mar 12, 2011 4:26 pm

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After sleeping on the flow problem I came up with a simple solution which I thought should work, restrict the flow at the throat before the outlet. Instead of adding regulating valves on each and every outlet which will attract and increase cost, I guess the simplest way to achieve this is to reduce the diameter at the throat by inserting a sleeves. Got hold of tubing of different diameters and cut short section of it to make sleeves. Inserted it into the throat of the outlet with the fastest flow rate and the result was encouraging. I had turned the flow regulator valve to feed the grow tank at the most minimal rate as possible in order to see the effect of the flow.


Sleeving ( photo / image / picture from KK Ng's Garden )
After lots of trial and error in establishing the diameter of each throat with all sorts of tubing and even plastic drinking straws, I managed to get the almost best even flow rate for all the 5 outlets. Once this is established, I can then adjust the cycle time . While adjusting the cycle time, I noticed that the drain did not stop and continue trickling at a steady pace. Oh no not another problem! Could it be the draining rate equals the feed rate? Checked the siphon hose one by one and confirmed that the two grow tanks that is the furthest away from the fish tank is the culprit. If the feed rate is equal to the drain rate then increasing the feed rate would solve the problem so I thought. Tried increasing the feed rate but problem is still there!


Version 1.0 ( photo / image / picture from KK Ng's Garden )

Version 1.1 ( photo / image / picture from KK Ng's Garden )

Insurance ( photo / image / picture from KK Ng's Garden )
It was getting late and decided to pack it in for the day and surfed the net till late at night looking for a solution but there was none. The next day I thought could be the air access hole being too small to break the siphon must be the problem and decided to make them bigger. It was a tedious task having to remove the pebbles from the two tanks but it was done after nearly 4 hours. Since I had all the pebbles removed from the tank, I decided to add a cage to the opening of the siphon tube to reduce the possibility of getting blocked in future. All the siphon system have the same size air access hole when I made them so I decided to redo the other three tanks as well. Even though it is tedious, if it must be done, it must be done - better safe than sorry or is it better now than later? Anyway cages were also installed as well to be on the safe side


Pho bo - yummy ( photo / image / picture from KK Ng's Garden )
The next day got all the components and pebbles back in the grow tank and got the pump running again and ...... no, no...oh NO!!! it was still not working. Ah well, decided to help Becky with the very delicious "pho bo" or Vietnamese beef noodle soup preparation for lunch. This was the very first time we were making it and it was really yummy. After satisfying my tummy and rested, I headed to the aquaponic area to look at it again. Hmm ...... this maybe if I can just see what was happening under the pebbles maybe I would be able to find a solution.


Siphon 5 ( photo / image / picture from KK Ng's Garden )
OK I decided just to make an opening in the pebbles until I can see the cage and observe the whole process from fill to siphon to break siphon to fill again. It was a long wait before the siphon started and again a very very long wait for the siphon to break because it did not. The siphon just slowed down when it reached a certain level and equal out to the feed, when I push the siphon loop lower the siphon speed increases. This must be the culprit, remove the hoses of the two problem tanks and compared them with the others and confirmed that they were shorter. Guess what, this problem was self inflicted, remember when some of the water was purging out during the very first run I cut the hose shorter to ease the flow, guess I cut a bit too much.

Now to set the cycle time.






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Jerry Sullivan wrote on Sat Mar 12, 2011 11:22 pm:

Hi KK,

The trials and tribulations of designing a water system seem to have plagued your aquaponics project as they did the engineers of ancient Rome and Angkor Wat. I could ask a lot of questions about calibration, water pressure and flow volume but you appear to have things well in hand. Except for loading and unloading all those pebbles!! KK, you are making me tired just thinking about it.
Question: would a bleed tap on the supply line back into the fish tank allow for easier volume regulation than a on/off valve?

Just a thought,

Jerry

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KK Ng wrote on Sun Mar 13, 2011 4:47 am:

Thanks for the compliments Jerry, I am flattered.

Bleed tap, I guess it is just a matter of preference.

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