Backyard Aquaponics
A place to discuss aquaponics

Hi to all,

When i designed my system i wanted to believe that media filled growbeds, if properly dimensioned (and with systems with low stocking density), act as filters and that filtering of the water coming from the fish tank is unnecessary. I've read many times that growbed cleaning in these type of system could be needed only after a long time, 4 to 5 years or even more.

But sad to say this is not true to me. I've been running my system for two years and my expanded clay filled growbeds are totally clogged. Water is not circulating properly (filling and draining very quickly), there is a thick layer of mud on the bottom of them. Also, since a couple of month my pH is not lowering, it's been two month since i haven't added any buffer and my pH is at 7.2/7.4.
Cleaning the bed is a pain, and it will force me to start over some crops that are adult already and will not survive the transplantation. Two years is coming too quick for me.

I should have listened to Wilson Lennard who warns that without filtration growbeds must be cleaned of a very regular basis.

So i've made my decision and will clean the beds and add a fliter to collect solids (and mineralize them offline).

My system is on a tropical climate, so fish are eating and crops are grown all year round. Maybe that explains why the beds got clogged so quick.
Just for info, my stocking density is 40 plate size tilapias for a 250 gallons fish tank, and two 35 sqare feet growbeds. Feeding is low : about 60 grams per day.

Hope my experience helps some new aquaponicists.

IMHO your grow bed volume is not enough for 40 tilapia at plate size.

Tilapia is one of the most pooping fish. With tilapia, it is almost compulsory to have both RFF and an MBBR to remove all sort of solids so that your GBs can stay clean longer.

I think you need to lower the density of fish.

Do you have red composting worms in your grow beds?

I agree system is overloaded

I'm shifting my systems soon and will build in a solids removing filter so I can use it or bypass it as required.

Of course fish load changes as they grow or are replaced with little ones or we eat some ect ect .

So its a bit of a balancing act .

And yes in your climate the load is all year round , here the fish feeding slows 90% through the cold months

So sounds like your on to it have fun with your modifications .

Coming up to 5 years and the beds here are not clogging up at all. I had a filter but have isolated it as I've realised I'm too lazy to clean it on a regular basis.
I've found that if a gb shows signs of too much organic matter in the media, leaving the patch barren for a couple of weeks after harvest seems to clean it up. My system is timed f&d and I occasionally like to remove the standpipe overnight to totally drain the gb. I also like to flood it over night too... I find it amazing the way the worms clean up the beds so well. I have found the plant matter more of a problem than the poop.
But then I'm not overstocked.

That is the secret

Oh it ain't no secret mate.
It's just ignored. But then there is a lot of misinformation out there.
I'd be surprised if I ever will need to clean the beds. I think the day I do I'll pull the plug.

Or convert to DWC

After 4 years of running I had a system upgrade, a total dismantle and re-build, moved the fish tank out of the sun and cleaned all the grow beds and clay balls.

I was surprised that there was no build up of solids in the bottom of any of the grows beds at all and nothing needed cleaning at all.

The filters were a different story so they were doing their job OK.

Hello,

My aquaponics has been running for about 4 years with no filter but now it is clogged with mud and roots (thanks to sweet potato roots clogging everything).

I am just wondering how to clean it? I have expanded clay in the grow bed.

Last weekend I took all the expanded clay out and tried to wash out the mud and roots but that did not work as the mud had nowhere to run off too. I also cannot filter it through shade mesh as the mud is in chunks and doesn't wash away. It sticks to the expanded clay.

Is there a quick way to clean expanded clay as it seems like I have to scrub handfuls at a time, which will take me days and days to do.

Cheers,
Quinny

A quick way? Probably not.
Removing the clay and drying it out may work, shouldn’t take too long to dry at the moment though.
Or, a big bucket rinse and remove perhaps.
Neither easy ways though.
8 years now and I’ve not cleaned mine out.
Probably should though.....

Let us know your best method Quinny, when you’re finished...

I set up two empty grow beds to clean my media. I use a mesh planter basket (for pond plants) to scoop out dirty media and wash it in the first empty bin, then when enough is cleaned I scoop it into the 2nd grow bed. If needed I repeat the process a 2nd time, replacing the clean media in the original grow bed, then move onto the next. I cleaned two of nine grow beds last year, and at least two more need it this year. I did notice an improvement in plant health after cleaning.