Unclogging a Growbed

Occasionally I will have problem of growbed clogging, this mostly due to pebbles that is small in size was use in my set. This smaller pebbles will cause fish solids to get trapped and eventually compromise the siphon water supply.

A quick way of rectifying this is by making a "Brick Barrier" and filling the inner part of it with larger pebbles and finally top it up till full growbed height.

Above is a temporary measure if time or situation did not permit full growbed overhaul. There is also occasion where I use this Brick barrier as a replacement for the strainer itself, arranging it more tightly using the narrower part of the brick or less number of brick used.

Growbed Layers

How deep is a growbed ?

This is a highly debated subject, to me the deeper the better. Not to say you cannot grow in shallow growbed, you can. I did use 6" deep growbed to save cost and weight of pebbles and I also use 12" growbed lately for hydroton and pebbles. If you have deep growbed, there will be more surface area for bacteria to interact and produce more nutrient and as the result will clean water better.

Plants benefit from this too since they will have deeper root zones and better support, deeper root zones will equal to more food for plants.

Aquaponics Growbed have 3 distinct layers.

1st layer, the top most is the dry or barrier layer that expose to sunlight. This Dry layer or zone is necessary to reduce evaporation and algae growth. This layer in a way provide a barrier from sunlight directly having contact to water, apart from already mentioned effect it also reduce direct heat which is important at sunny area.

2nd layer, the middle layer this is where in flood and drain system water constantly rise and fall, air and wetting the media for biofilter action converting amonia to nitrites and then nitrates for plant use. This also the Root Zone where most plant roots are found. The thicker this zones the better it is.

3rd and final layer is where water may not be able to drain, stays and where sludge accumulates, this zone are called by various names, I just call it Sludge Zones. At this zones breakdown of fish solids occur by bacteria and worm. It is crucial to have a good drainage in this final layer. Recommended to use larger pebbles to ensure it does not easily clog up.

The thicker the growbed means the thicker the 2nd layer where most plant roots are concentrated for nutrient, therefore shallow growbed although it work. It will be less root zones for plants.

Having said that, pebbles growbed can be shallow due to weight issue and also they are able to provide support to plants even at 6" of depth.

As long as you know what you are doing, its not much of an issue with regards to growbed depth. I recommend nothing less than 6".

Apart from above layers, growbed drainage is most important to ensure trouble free aquaponics set and good plant growth.

Putting larger pebbles or stones up to about 2 to 3 inches for the first few inches of growbed dependent on gb height is highly recommended. It is then follows by smaller pebbles or hydroton to top of growbed.

The larger pebbles is to ensure good drainage and the smaller for easy planting of seedlings and sufficient area for bacteria growth.

Update : 4th. August 2015

It is recommended to use pebbles or rock larger than above picture to ensure they are easily separated if the media need to be replace. With better designed siphon or SilosGrowbed method those pebbles at the sludge zone  are no longer necessary.

Hydroton Growbed Redo

One of the hydroton growbed giving me problem with its siphon. As I recall this particular growbed was the first that I tried with hydroton in my set.

Emptied the growbed and what needed to be done is to redo the siphon strainer. It was a quickie job few months back while I am trying out the hydroton. The strainer from start I know will eventually give problem.

During that time I was using 10 mm drill to make the strainer, but it was too big and letting hydroton through. As a temporary measure I glued plastic netting to make sure no hydroton  pass. Current design is 8 mm holes and no netting required.

Above the complete trouble siphon assembly, what needed to be done is to make 8 mm holes on the top and strainer holder as in current design.

Siphon removed from growbed to rework.

Smaller holes drilled and strainer holder is also drilled for water drainage. It was not done earlier, adding problem to the siphon operation.

Stand pipe and reworked strainer holder installed.

Completed siphon, bigger holes on top is not required. It is there because I reuse the same strainer to make smaller holes on the other side and just flip it over.

Old and new side by side for comparison, inner parts not change.

I decided to put first 2 ~ 3 inches with pebbles, they are better at drainage. Took me about 2 hours to redo and get it back operating. Hope it doesn't cause any problem to growbed nutrient level.

Growbed Period and Tilapia Cycle.

I had been doing these for quite some times and decided to put it to paper, what I practiced in relation to Growbed Maturing Period and Tilapia Cycle.

This is for backyard and not intended as a guide for commercial venture where they will need faster Tilapia Harvesting and Growbed Maturity.

Above graphic representing the number of months in a year and at a location where sunshine is year round, no fertilizer or supplements except Iron in the form of few metal rods.

Growbed Maturing Period.

Stage 1 - Basic Maturity
Growbed bed maturity as most cases states at 6 to 8 weeks same as in normal aquarium, however in real situation this period can be longer depending on how well the water is controlled and other factor like aeration and sunlight exposure. At about 2 months there will be a sure sign of maturing.

During this period its best to try out simple plants to keep Nitrate in check.

Stage 2 - Intermediate (Medium) Maturity
Post Basic Maturity to roughly double the time needed as Stage 1. This is where bacteria and fish reaches an equilibrium and start to build up more and more nutrient toward sustaining full growth of plants and fish.

During this period, try various plants to ensure suitability in term of location, climatic conditions and whether suitable for Aquaponics planting.

Stage 3 - Full Maturity
This is at 6 months and onwards, this where system has reach its full potential and planting should be base on Stage 2 trial. Plants are grown to make it possible to harvest adequate quantity for household needs.

Tilapia Cycle

1 ~ 6 Months: Initial start of a system, fingerling are added and rear for 6 months with starter and grower feed.

7 ~ 8 Months : Fattening Period for Harvest, Normally Finisher are feed to these fishes.
Tilapia can be harvested after 8 months as in backyard setup, but I usually done it at end of the year after about 10 months due to slower growth that I wanted.

8 ~ 10.5 Months : Select few breeder like 2 males and about 5 females and keep them separate, watch closely, they could breed after 1 months. Separate those fry once detected and grow them in separate area and return breeder to stock for harvest.

10.5 ~ 12 Months : Once fry large enough at about 2 inches fingerling, you can start harvest those big tilapia for dinner.

Above are base on what I practice for household consumption and at a backyard environment.

Aquaponics Tips - Water Loss Compensation

Water loss is a big issue over here in hot equatorial weather especially during dry spell. It will affect more on smaller system, and to be away for a week or so then it could be a disaster waiting to happen.

To  compensate during this period of hot spell or unattended system running I decided to make a trickle water compensation into my fish tank. I saw it was done by Zulhairi in his blog site and it's a good idea.

I use a small tap and hose that commonly use for water filter and just metered the flow rate by adjusting tap position. I need about 5 ~ 6 liter per hour flow rate. The measuring container above was use to check how much water flow after about 15 minutes. The rest is just adjusting tap to get the approximate correct flow.

Update 22/7/2013 : After 2 days of operation, I readjust water to 4 Liter/hour flow rate. Will be monitoring these next two weeks.

Once I had obtain the correct flow, the small tap handle is removed and safe-keep, this to ensure no accidental closing or opening of this tap that could cause major problem to my set. Basically to keep off "small fingers" from messing with it. Full water shut off is by closing that water cock on the wall below the tap if trickle flow is not needed.

Water trickling into fish tank. Chlorine is not a major concern since the flow is too small.

Update : 11 August 2013

I left my Aquaponics set unattended for 5 days during a festive holiday, no problem at all with water level. It maintain just nice throughout the period running by itself. Water level sufficient and no sign of over spilling or too much water. Adjusted rate is 4 liter per hour drip. Total water volume in system is about 1200 liter and at 4 liter its will be about 96 Liter daily @ 8% compensation.

Siphon Overhaul

Original Home Kit that I made few years back was send to a relative house a short distance from where I stayed and it has been running all this while without any maintenance. So must be close to a year already running on its own.

Its in very bad shape however still able to produce those simple vegetable yam and Tilapia. Pump not in a good working order, aeration pump leak and since water inlet inconsistent siphon operation is at its maximum disruption.

Its shows how hardy these system is even without much care its still going on and on. This set is the first home kit that I made. Its big compared to my current design that I posted few pages back. 

Proven, those Tilapia was breed in house and now they had grown. I am sure those smaller Tilapia are from this set itself. Since a few had been harvested for consumption. 

Those that are curious, these Tilapia do not has that unpleasant smell from being breed in such a small space and the water too do not smell. We rely purely on rain water to replenish.

Siphon in a bad state too,  strainer has been dislodge from growbed that silastic glue don't seems to hold. It may be due to movement made by the current taker and roots invading the enclosed area.

Stand pipe remove and will be reuse, no problem just dirty that's all.

All parts of siphon removed to redo, I inspected all parts nothing damaged. After some cleaning its all set to be reinstalled.

Strainer, bell and down spout above and pump below. This pump need to be replace, or at the minimum the impeller change since its spindle already worn to critical level making pump starting difficult.

This time I use hot glue to hold strainer to growbed, they are much stronger. You can forget those silastics, just use that hot glue gun with its glue stick. They are much cheaper for me in the long run and harden in a short time.

Original bell installed, this siphon was made for 8 inches growbed, but should be able to do 12 inched.

It is shorter that all my current siphon which made for 12 inched growbed. It works so why bother to change.

Siphon completed all needed are those pebbles and at more water to the Tilapia tank.

No Pain No Gain

Another growbed need replacing its lumber support, its rotting. This is one problem that I very much afraid that would happen when I least expect it.


Little choice did I have except replacing it with fresh lumber, I seriously have to think of something else other than lumber to make these growbed support maybe I'll try concrete beam next.


Since I have to empty the growbed, might as well redo it to make it better. So, I decide to put 2x4 lumber bigger than previous 1x2 so that I could do 12" growbed... yeaaaaa... !!!

2x4 in place, next would be fresh set of siphon. I decide to go small, its a 25mm siphon except the bell and outer strainer is reduce in size. This siphon is the normal 25mm stand pipe but I use 32 ~ 25 reducer making it small enough to use the 50mm bell with 82mm uPVC as the strainer.

This siphon above use the same strainer as my mini 20mm siphon. So the bell and strainer pipe is same size, this will make it easier to fabricate. My only reservation is roots growth, being a smaller strainer its would be difficult to get access inside it. However from my previous experiences roots don't really did much harm in the setup.

All cover up, its not exactly 12" but close, this blue tub height is 12" so there a bit left to fill but not that critical.


One by one I am planning to upgrade to 12" growbed, it does takes time. Normally I wait for something major to happen only then I do it. Its a hard work to do it all in one evening after work,  I'll sleep like a log tonight.


Update 4th May


Plant Turmeric in this bed, I'm redoing this plant to see how it grow in thicker growbed. This is a good cash crop since its leaves is use for flavouring. Matured leaves fetch about USD 0.10, and this plant can provide cash flow if grown in higher quantity.

These Turmeric are from growbed next to this.

Growbed Lumber Support Break

One of the support for the growbed broke, its probably rotten by water and sun. Its sagging to one side, no other choice but to replace it.

Its going to be hard work today.

All 200 kilo of gravel need to be removed before I could lift up the growbed. Luckily most of the cherry tomatoes already towards the end of their life cycle.

Few container ready to receive the gravel, I need to do this fast to prevent drying of gravel killing those bacteria resulting in longer time for growbed to cycle.

Once all gravel removed, blue growbed out and need to put fresh lumber as support.

I have a few used lumber standing by, for this situation. Next time I better use steel beams to support its will last longer.

On goes the growbed and water inlet done to make it heavier for me to adjust. Its higher than growbed next to it due bigger lumber used.

Before gravel in, this is a good time for me to redo those hexagonal brick arrangement for the siphon cage, I decide to arrange it side ways to make it smaller as compare to previous in following picture.

Previous arrangement below.

Gravel in... almost done...

Finished ... two hours of hard work..  :)

Lemon Grass Growbed - Redo

Lemon Grass is a hardy plant, well grass actually its able to grow in horrid condition and tolerate low fertility and low moisture content soil.


In order for it to grow in these condition, lemon grass has a very active root system and its very much intrusive most of the time. In Aquaponics where we have siphon, intrusive rooting plants or grass is a nightmare to upkeep.


I would recommend if you want to try Lemon Grass, plant it as far as possible from the siphon and its best to have it on a large growbed.


So in short it has to go.

I tried Lemon Grass to see whether they can be grown in Aquaponics. They thrive very well thank you, however the size of their bush and value to the kitchen don't justified this grass to be grown in Aquaponics. Due to my acute limitation of growing space I need to keep only those plant that will give maximum yield or usefulness to my setup.

Lemon grass and Okra removed from this bed, that Pandan is next. I will need to trim this Pandan to its minimum. Below what's left of Okra plant.

Pandan and Lemon grass in bucket of water, I will give these away.

Once all unwanted plants removed the dirty job starts. Roots matter need to be remove and how else to be done. Hand pick is still the preferred method.

This is the dirty job part of Aquaponics, those Lemon Grass sure have lots of roots. Plants like Okra is easy, pulled them out and most of the roots follow. 

That growbed in the far end also need a minor redo, I do that next month. We can't do all growbed at once its bad for the system balance, you may get Ammonia spike and problem to the fish.


Its not as bad as it looks.

Once all rooting matter out , I redo this growbed. I am trying out using brick arranged vertically to form a hexagon cage around the siphon. Hexagon shape arrangement make the brick able to support growbed material around it.

Below at high water level. This growbed is about 1 brick length high about 7.5 inches, its not optimum for growbed. Its best to have it like 12 inches, however I am using pebbles for growth media its going to be very heavy if I make it 12 inches. A compromise at about 8 inches so far so good.

Below siphon at lowest water level. The strainer pipe is not needed with this arrangement but I decide to just leave it there and see how its goes.

I like to make things as flexible as possible so that we could expand as and when required, so if I need to increase the growbed heigh to 12 inches I just need to put few brick on top of existing, lengthen the siphon standpipe and add more pebbles.

A circular open ended porcelain or clay cylinders also will do the job. I will try to look for something like that next time I do the siphon.

Its about time that I redo the water feed, so 20mm pvc feeding water to growbed on two sides, and below is my make shift water flow indicator.

I will try Cherry Tomato on this bed, I already sown theirs seed three days ago.


Update : 19th Sept

I covered the hexagon cage with pot tray so that algae do not grow within the cage.