Backyard Aquaponics
A place to discuss aquaponics

They might not have been much help to you CTree but pictures would have been handy for us.

I'm not sure if anyone has mentioned it but you said the RFF would go back to the fish tank? This is not the best way. A RFF is designed to capture the large solids. Thats means that there are still a few fine solids plus all the ammonia. Standard way to do things is to send the flow from RFF to the GBs where the remaining solids will get captured.

On how much you are feeding...

225g divided by 6750g is 3.3% per day. Since the feeding rate is rather high, especially for silver perch is it possible your beds are not being clogged with fish poo but rather uneaten fish food? Un eaten fish food counts for about 5 times the same amount of solid waste.

and if the grow beds clog, that too could be a bigger problem..

Remember that you could fit a pressure bypass to the filter.. ie.. a "T" on input and output, that rise into the air and connect together.. with another raised (OPEN) pipe for breathing.. (all, depending on your complete design)

Have not got to the comments but WORMS - do you have lots.. they would reduce the bulk of the solids..

+1 to the feed rate - more that twice the recommendations via Rufus
10cm fish = 40gms x 90fush >> 3600gm @ 3% = 108gms

and where are you in Sydney.. I'm near Hurstville..
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Hi,

Yes, it is possible that that is what is clogging up the GBs.

The thing is that the fish appear to eat all the food. It's floating food and after I feed them then it's all gone. In the past perhaps it wasn't and that is what is clogging the beds.

The question I have is:

With the 1 to 2% number, is that the best amount to feed even though the fish will eat more? Should I not feed as much as they will eat?

As long as they are eating the food is that not good? After all the fish weight is an estimate. Especially as I can't see how big they really are .

I'm in Burwood.

Not sure if the pressure bypass would work as the filter is pressurized because water flows from ft through filter then on to GB.

Have quite a few worms.

+1 on Stuart's comment. A Radial flow filter would go a long way in your system. And looking at the designs for them, there is no reason that you could not run it besides your pressurized filter. You would just have to buy the proper 55gal drum(s). The ones with a locking ring type lid (or screw on). For your flow rate I would split the flow from your pump and run through 2 separate 55gal RFFs. So the particles have enough time to drop out of the water. Here is a link to a discussion on Kiophen that shows the dimensions of commercial units and flow rates. Pretty informative. http://www.koiphen.com/forums/showthrea ... ow-Settler
Here is a quick sketch of what I mean. It is a decent amount of piping and ball valves. But the upside is you would never have to shut your pump off to work on or clean out any of you filters. Besides that you could keep money in your pocket by not having to replace the costly canister filters. As you would only run it when you needed to. Hopefully never again

You could also Just copy Ryans version. From his backyard thread. viewtopic.php?f=18&t=8754

For some species yes. For fish of a particular age yes, well maybe. For others no.

If you over feed your fish they will store the excess energy as fat. When you gut the fish a large proportion of this fat is wasted when you remove it with the intestines and all the other organs.

If you over feed them too much then they can get sick from being too fat.

Crazy,
After thinking about it some more. You would not have to use a drum with a lockable lid. But you would have to either run the RFFs or the canister filter at different times. As the backpressure in the line might back up to the RFF and render it less efficient.

Stu,
Any information on Tilapia? Which category of feed that you listed do they fall into? Blue if it makes a difference.

My knowledge of tilapia is only theoretical and even that is limited because they are illegal here. I've got a bit of an idea but there are others on here that have more knowledge when it comes to tilapia.

Stu,
Thanks for the reply, and honest answer

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In case some one were to search and find this thread, I thought it best to share my experience with CANISTER type POOL filters..

Love them - in their place.. IMHO

First off - they are great, but you must know your planned system and plan the filter process..

eg.. I started with three GB's and a timed Flood and Drain..
FLOOD for X minutes, DRAIN for Y minutes..
The canister filter did it's job perfectly, keeping all solids from the GB's.. ( except for the constant clay powder shedding )
BUT - then I changed to simple auto siphons, to cause more of a RUSH of water into the FT's..
I found that after a time the siphons failed to activate.. the water flow had slowed below the critical minimum needed for siphoning.. clean the filter and all good again - NOT a satisfactory solution, because you could never be sure of WHEN the filter needed cleaning..

In my second system I still have a canister filter, but this time I used two smaller pumps..
One for circulation to the MEDIA bed (Unfiltered), and the other pump to the
canister filter > to the Bio Filter > to the FT, thence SLO to two swirl filters and back to the Sump..

Bottom line - Mechanical filters do their job but you do need to understand the issues when they need cleaning..
Keeping solids OUT of my Bio-Filter, is my goal..
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