Backyard Aquaponics
A place to discuss aquaponics

I have a 1000l FT and have just picked up my sump which is about 270 litres. I was only gonna do a single GB but not sure how big to do it?

Are you building it, or using an IBC/blue drum as a grow bed?

If you go constant flood, you can make it as big as you want.

Hi Pronga, it also depends on how many fish you want to stock as it is the bacterial colonies on your GB media which convert toxic ammonia that your fish excrete to nitrite (also toxic) and then to nitrate for you plants. Worms in the GB also break down the fish waste solids. The oft repeated rules of thumb thread has some great info on fish stocking rates based on amount of GB biofiltration you have - I recommend you have a good read of the thread and The IBC of Aquaponics before you finalise your design, and post your design to get more advice before you build.

From memory, you will need at least 25 litres of wet GB media (not counting the dry top few centimetres) per plate sized mature fish (~600 grams) that you want to grow out. For example, one IBC growbed cut off at ~400mm will give around 300mm depth of wet media which is around 300 litres, so you could have up to 12 trout. If you want more fish, you need more or bigger growbeds or more sophisticated mechanical filtration which will make your system more complicated and higher maintenance.

Colum has a great video on making GBs to whatever size you want - check out his thread.

I am new to AP this year, and have found that you always want more fish and more planting space especially after seeing other members amazing systems, so make sure your initial design, sump and pipework are big enough for a bit of expansion.

If you have the space, I would suggest you keep the 275 L sump as a growbed, and get another IBC and cut it at around the 300mm mark to give a 700 sump and another growbed. Then your sump has the capacity for 3 or 4 ebb and flood growbeds without running dry or overflowing if they are all filling or dumping at once. As Colum said, with constant flood you don't have this problem.

Welcome to the wonderful world of AP and have fun!

Please help me out I've made a Google sheet based on the bio-filtration from this<br />http://biofilters.com/websize.htm<br />My numbers i calculated from the site are on there im not sure you can view the formulas.<br /><br /><br />https://docs.google.com/a/smithville.k1 ... sp=sharing<br/>