Backyard Aquaponics
A place to discuss aquaponics

Do you have any compost worms you could throw in your media beds? I don't remember, are you running your beds constant flood, or flood and drain?

Are they flood and drain? Or Constant flood?

Black and slimy and especially stink are bad signs.

Yes, if you think that more filtration is needed, you are probably right!
I personally like to have twice as much gravel bed as I have fish tank. That isn't necessarily needed to provide nitrification but it is a good starting place to be sure you will have enough solids filtration without having to add solids removal. If your system has a heavy load of leaves and gunk beyond just the fish waste, some sort of filter that can remove some of that might be of use.

thanks TCL, I have spent a fair bit of time cleaning out the FT of leaves and stuff, but there is a fair amount of fine muck (fish poo I guess) which is hard to remove as it is very fine.

I have ran the pool pump and sand filter (a few times) which cleans it up quite well, but it tends to also suck up some fish or yabbies so I've not used it for a while.

if more grow bed / filter area is required I need to onto it.

The problem is a lack of room! possibly a set of 25 zip towers or similar is the answer?

It's flood and drain 15 min on 45 min off.

I was promised some worms by a "friend" but they have not delivered yet

So I urgently need a lot of extra bio filtration.

as a temporary measure until some more GB's can be organised would this work:-

a large tube ( maybe a soak well ) with slots around the top filled with a media like bird netting or such,

under it an air stone bubbling and inducing flow from under the lower edge and out the slots around the top?

If you are working in a confined space greenhouse with some temperature control, the Zipgrow towers are a really good way to get more filtration and also utilize limited light in a High Latitude region.

For JUST filtration purposes. If you have an overabundance of solids and can't provide enough plants to use the nutrients anyway. Look into setting up a radial filter to collect and remove the solids. Depending on system size, this might be done is something as small as a 5 gallon bucket or 55 gallon barrel. I've actually set one up in a 100 gallon stock tank even. Then you let the solids settle out for a while and can periodically remove them and feed them to the compost or worm bins to reduce the load on your system.

My system is a pool conversion and is very restricted space wise, I have used the deep end of the pool as the FT (7000L) and have grow beds in the “shallow end” (1750L) the back fence is my only available planting area with sunlight left to use (thus towers).
I have used the pool pump and the old sand filter, but thou it cleared the water well the plant growth didn’t improve?
Also the pump struggles with the extra 1.5m of suction head and I was advised not to use the sand filter? So it’s not been used for a few weeks.
There seem to be a number of systems on this forum with large water volumes albeit with low stocking densities which suffer from poor plant growth. I was thinking that the ratio of water volume to bio filter was affecting the nitrification.

With really large water volumes (often not shaded and not easy to keep leaves/debris out) it can be hard to keep algae and debris from fouling the system to keep the water nice. It isn't so much that the VOLUME of water is a problem since Raft aquaponics works and they have a huge volume of water. But that it is hard to get the bio-filtration, solids filtration, plants, and circulation all balanced for a functional system.

With basic standard back yard aquaponic design the rules of thumb are things like
a-circulate at least the volume of your fish tank each hour.
b-have at least equal volume of media bed to fish tank if not twice as much media bed as fish tank for max stocking.
c-have extra aeration some how.
d-cover your fish tank to avoid algae problems, keep fish in and debris, small animals and children out.

with a pool or pond size system, some of these things are hard or impossible and the rules are almost never followed.

As to the sand filter, they take pressure and if you leave them shut down and then turn them on again, you are likely to be injecting anaerobic bacteria into your system from what has happened in the sand filter while it was shut down (it only takes a few days for what is left in a sand filter to become really nasty.)

Yea, most in ground pool pumps are only designed for a suction head of perhaps 30-90 cm.

You might be able to use an airlift sort of thing to try and filter out algae and debris from the pool without the problem of clogging fouling that sort of just sometimes causes with submersible pumps.

Yes I was thinking of a combined filter and air lift.

Could the sand filter be managed by back washing before using to filter FT?

or maybe running it every day or so?

If you manage to get enough filtration, you really don't need the sand filter. And the fact that the sand filter is going to put more stress on your pump trying to pump enough through it when it is already over it's suction limit. But if you ARE going to use the sand filter, when you first use it, there is no help some of the nasty bacteria are going to get flushed through your system even if you backwash first but once you put it back online, I would say you need to use it for at least several hours every single day. If it doesn't get used every day it will go septic.

I have been looking for instructions on making a Radial Flow Filter and or a Swirl filter and am more confused than ever after dozens of different ideas.

Is the RFF better than a SF for fine fish waste etc

So a swirl filter creates a swirl from the bottom of the bucket and the RFF the water goes up and down and up again?

is there a formula for flow rate / filter volume required to give ideal filtration or is it trial and error?

For swirl filters and regular settling tanks there are definitely formula for figuring out how big the tank as to be to handle the flow rate of water to allow the solids to settle etc.

The radial filters might have ideal flow rates for BEST operation but they seem pretty effective for knocking down the solids and allowing primarily clear water to pass with the least attention to the fine details and formula of size/flow rates.

So if you are not going to be spending a lot of time/money getting specialized cone bottom tanks of exactly the right size for your flow rate, then I would say go with the radial filter.

Or I'm sure it is possible to do a combination.

thanks TCL, I will start building a RFF.

anybody have uniseals in Perth?

Slowboat, feel free to pm me with your uniseal requirement.