Backyard Aquaponics
A place to discuss aquaponics

Hi All,

I'm currently plannning a refurb of my existing system. I'm going to ditch the IBC's and go with 2mx1m beds like the BYAP growbeds.

Does anyone have any alternatives that are not so expensive? I'll be needing 10.. nearly $4,000 if i bought those.

Thanks

Some sort of liner based approach is the cheapest way I've found to do gbs.

Checjout TClynx's system thread for some ideas

Thanks, I really dont wanna go down the liner route.. I'm using red scoria so it will have a tear risk

I think you need to do some more research on liners.

There are plenty of options that can be used with scoria which as rocks go not that sharp.

How would you shovel out the rock safely when its time to clean the GB..

At the risk of kicking off an oft repeated debate....

If you have sized you GBs to a size appropriate to your waste load from your fish you shouldn't ever have to clean out your GB.

The are a large number of longtime APers on this forum that do not clean their GBs and they have not had any problems. What is common to them is that they have relatively low stocking rates of fish relative to their systems GB size. In other words they have an appropriate ratio of GB volume to their stocking rate.

The only exception to this that I know of is F&F who noted a decrease in GB productivity after 5 years.

Others will chime in on this but everything I have read, seen and experienced is that as long as the ratio of GB size is massive relative to the waste load that is fed to them you shouldn't have a problem.

With the possible exception of F&F everyone who has problems is because they are over stocked relative to the amount of waste that is being delivered to the GBs.

This is not just a matter of how many fish per L of GB volume but rather the size of the fish and how much they are being fed and the protein content of the feed. For example Trout being grown under ideal conditions fed an appropriate feed (~45% protein) may consume 6% of their body mass per day will need masses more GB volume than tilapia being fed a feed containing only ~35% protein 1-3% body mass per day.

All that crap has to go somewhere..

This is why i now run a radial flow filter.

Yes you are right it does have to go some where but once it has gone to a gravel bed it doesn't stay there.

Either way, im actually coming around to the idea of making them myself using liner - Primarily because i do have the filter in place, it should minimise any need to clean the beds.

Ive got an 8M x 3M greenhouse so i'm thinking of running 3 (2Mx1Mx0.350) grow beds down each side
1 (3Mx1Mx0.350) across the end

I've got a 4,000 litre fish tank - so i'd like to get to a 100 to 150 fish stocking level.

My 2 X 1m GBs cost me $250 each, although freight to Vic from Newcastle might be a bit expensive.

I have 8 mostly full GBs and a 4000l tank with 77 only half grown trout, and my nitrates are running a bit too high ATM, so I probably need more GB area, although Wilson Lennard's calaculator says I dont.

Have a look at my system grow beds pond liner. That is the cheapest in the world. If you like them, I will explain.

Here is how I build my grow beds using standard dimensional lumber:



Legs:

4 - 2x4x36"
4 - 2x6x36"

Sides:

2 - 2x8x51"
2 - 2x10x51"
2 - 2x8x96"
2 - 2x10x96"

Floor:

1 - 4'x8' plywood sheet
2 - 2x4x96"
7 - 2x4x45"
10 - 2x4 galvanized hangers

How much does that timber etc + liner cost you Jeff?

I have used a similar layout as Jeff, except using pine sleepers for the bottom as well. Cost using treated sleepers and high quality liner was around $180 for bed with volume of 0.4m3.


timber = $100
screws and glue = $10
liner = $50
odd & ends = $10


gabe

If its simply stocking levels for the fish, put inline a more efficient biofilter and increase your mechanical filtration.