Cheap and Small Aquaponic Auto Siphon (Growbed Space Saving)

Dear everybody,

This project will be useful for whose space within growbed is a problem, or have only a "small" growbed.

Just like my problem, I intended to "start practicing" in aquaponic world using smaller scale growbed. Searched around reference from internet, mostly recommend BELL SIPHON.

Unfortunately this kind of siphon occupies too much space within growbed. This is not so kind for my small growbed :) Because we want to grow as many plantation as possible :)

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Step 1: Make Your Solid (Grow Media) Filter Using Small Bottle!

OK, this is important point since effective growing space in growbed is to be made as much as possible.

  • Search for small unused plastic bottle (I recycled ex. cajuput oil bottle - made in Indonesia). Wash it thoroughly to ensure no harmful chemical left to your fishes and plants!
  • if you do not have small plastic bottle, you can use long bottle then cut the mouth and the bottom from the body (see above 2nd - 4th photos), then join them together using glue.
  • once you select the plastic bottle, drill some hole (5th photo). I found punching holes using heated nail (6th photo) is neater than using hand drill. And it was also faster.

Step 2: Install Your Solid Media Filter

  1. Drill a hole at the water lowest level of your growbed. Mine is around 3cm from growbed base. Enlarge the hole using your drill by moving it around until close to your bottle Outer Diameter (tight-fit is better/stronger, Photo 1)
  2. Insert your small bottle (Solid Media/Gravel Filter) to the hole, apply glue at the interior and exterior

note: I found small water leakage on this gluing process is not critical. This siphon is still working fine even with small leakage.

Step 3: Build Your External Siphon

  1. Shape PVC tube as per Figure 1 (U Siphon). You can use elbow for more beautiful look (Figure 2). However I prefer using “heat and bend” method, using what I have on hand to minimise cost and shopping time.
  2. Join the “Water Lowest Level” end to your “Solid Media Filter” using glue. If both diameters are tight-fit, you can skip glue. Small water leakage is fine. My siphon is still working fine though it has small leakage.


  • There is one other good thing about tight-fit mechanism; you can rotate the siphon tube to adjust “water highest level”. It is feasible though the cycle is running.
  • 90° bend at outlet is optional, to ease the auto siphon to start. I removed this in my 2nd siphon. If you remove it, ensure the “outlet” is kept below “Water Lowest Level”. Otherwise, your siphon will not stop at intended lowest level.
  • “Water Highest Level” determines the maximum level of water in your growbed. It shall be around 5-10 cm below media for good aquaponic result: avoiding invasive algae growth. Good indication for this is when you can see growbed media top is dry, then algae will never grow on it.
  • “Water Lowest Level” determines the minimum level of water in your growbed. I set mine around 4 cm from bottom of growbed. This space is for nitrification bacteria to live in.
  • Best minimum grow media depth for all kind of veg is 30 cm (ref: FAO).
  • ½” PVC tube is actually too big for small growbed. The “ebb and flow” cycle become too short for my small growbed. You can use smaller tube if it is available in your country. Other non-degradable material is OK to use (e.g.: stainless steel, brass, anodised aluminum tube)

Step 4: Test and Use It!

  • Flow water into your growbed tank before adding media (Figure 1).
  • Ensure the “ebb and flow” cycle is running correctly at intended highest and lowest level. If no, adjust the inlet water flow using ball valve.

Too fast inlet water flow will cause siphon never stop, too slow will cause siphon never start.

  • Once you are sure the cycle is consistently running, you can add media. My siphon is still working fine till today (6th day: Figure 2). You can see the sprouts are growing (Figure 3).

Finally, feel free to leave a comment or post a question of any problem you have with your siphon. I can also barely answer a question about “bell siphon” :) .



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    7 Discussions


    Reply 2 years ago

    Hi Fernando, thanks fot the very smart question :)
    I observed this individual u-siphon sometime failed when the inlet water flow from pump is not stable (e.g. when the pump started being clogged by the fish feces, or when the pump electricity voltage was dropped).
    Therefore I joined both growbed outlet/siphon together (using PVC T-Joint) to be one u-siphon only. It is still running well till today. As you can see I have green vegetable growing :)
    My aquaponic is indoor, under the terrace. It has limited sunlight. Therefore the salad, kale, mustard failed growing after the sprout stage.
    The vegetable you saw in the following photos is katuk leaf (in Indonesia known as daun katu/katuk). It can grow well with limited sunlight.


    3 years ago

    what are u using for grow media? And what kind of fish do u hav? Just got a greenhouse and really like the no electric idea !

    3 replies

    Reply 3 years ago

    My grow media is splitted (hammered) brick-stone (burnt soil). it is cheap version to hydroton. Same benefit (porous, organic, did not alter PH: good for nitrification bacteria and fish and plant).

    But even better because it is weighter. our plant will not be collapsed easily as when we use hydroton.

    Fish: koi, comet, oranda goldfishes, guppies, mollies


    Reply 3 years ago

    Thanks ! I found 275 gallon "totes" that have a metal frame around them for my tank and people are cutting them in half for grow many great people sharing ideas ! Thankyou again


    Reply 3 years ago

    that's a good volume of "big filtration media" to your big fish tank :)


    3 years ago

    what are u using for grow media? And what kind of fish do u hav? Just got a greenhouse and really like the no electric idea !