Backyard Aquaponics
A place to discuss aquaponics

Is there a lifespan for the grow bed? Assuming the grow bed is made out of something like pea gravel, and is acting as a particulate filter as well as a biological filter, it will eventually become clogged up with solid waste right? Does this mean the beds have a limited life and should be routinely renewed?

Interesting question OzV... From what I have seen, heard and experiences so far, it will depend on the type of system you have.

My continuous flow system has had the bed cleaned out once before about 18 months ago, and it's almost due for another clean now as it's starting to clog up a bit in places.

The flood and drain system has been going for a couple of years now and the gravel is still good there seems to be very little build up, and what build up there is in a few places doesn't seem to effect things much. There are worms in the beds, perhaps they are helping to keep things clean and flowing..

The Speraneos, who have done a lot of experimenting for many years have never cleaned their gravel beds to my knowledge, they say that the growbeds act as 'fluidized bioreactors' that break down any solids. No solids = no problems... I'm yet to experience any in the flood and drain...

Maybe a plantless smaller prefilter might help avoid clogging in a continuous flow system????

Yep, a settling tank to let the particles drop out of suspension... But then this is part of the reason why I like the flood and drain, your not taking anything out of the system, nothing is wasted...

Where do solids go then if they don't end up in the grown beds (to clog it up I mean) in the flood and drain system?

They do go in there, but they are broken down into finer particles and nutrients that are absorbed by the plants or continue flowing through the system untill such time as they are broken down further.

Ok - makes sense - I guess the flushing action of the drain cycle is enough to 'suck' the solids through the media too and help 'pulverise' them into small useable portions.

Do you use something like a toilet cistern for the flushing mechanism?

No there's no real hard flush, the growbeds are filled with water and any suspended solids. Then the water slowly drains from the growbed over about an hour. The solids seem to break down due to microbal activity within the gravel, they literally tend to just disapear...

The Speraeos I mentioned earlier have had gravel growbeds for well over 10 years now, and all they ever do is give them a quick rake over between crops to remove bits of roots and plant matter left from the previous crop. Roots left behind from previous crops is more of a problem than the solids suspended in the water, and mostly any roots tend to slowly break down and get eaten by the worms.

Yeah - I have looked at the two pump flood and drain setup you've got on your website and I am having trouble seeing how it works. Are the two pumps on all the time? Is their flow rate matched or do they come on alternately from timer swicthes? I had been playing with a flood flow design like this (please excuse the Dr Seus fish lol Kids! lol):





where the pump is on a timer that gets switched on an off at regular intervals and when it's off the water syphons back through the pump into the main tank but I was concerned about the strain switching on and off might put on the pump. I guess the cycles are not that short so it wouldn't be fast switching *shrugs*. I like how the pipes in yours stand up and out of the way so if you could explain it that would be great.

This is gunna need a new topic.... and probably a couple of diagrams as well to try and explain....

OzV, I bought "The Book"and it is all in there. I would strongly recommend buying Joel's book - It's worth every penny if you are serious about Aquaponics..... This is not a paid advert for the book, but I really recommend it....not everything is in there, re looking after fish etc, (as is evidenced by my skills in killing perfectly good fish after reading the ""book")
But as far as systems go it is worth the money
Murray

Murray,

As my first post, I must say that the more people get onto this the better because it is ovious that everyone knows bits and pieces about all different areas of aquaponics that we can all get heaps out of. I was reading your post on the dead fish and felt really bad for you .
Have ordered the book, just waiting for the mail, and someone to give me a hand cleaning out my garage...

Monya

How are you Monya..? Good to see you here.....

Couldn't agree more with you about the fact that more people should be getting into aquaponics, and you've come to the right place for info and help...