cascading or layering Grow Beds

[Dufflight]

What does everyone think of layering GB's. Filling the top one and letting it drain into another GB's before returning to the FT. Does allowing the water to go through twice the amount of GB's give the bacteria more time to process the water. I installed a 380ltr Gb yesterday on the ground next to the FT. And was thinking of putting the next one on a stand beside it. They are 40cm ish deep, so low profile. Has anyone worked out how long it takes the bacteria to work. I've heard its good to have your FT volume go through the GB per hr but does it only take one pass to convert or does it take a couple of passes for the bacteria to work. And if that is the case then running the water through more media would help cut down on the pumping time.

[Alwyn]

Well I am new to this and have not tried it but was thinking exactly the same thing.

The only concern I had was that maybee the last bed would not recieve enough nutrients.

Thanks for posting the question.:)

[Outbackozzie]

It works fine :)

It requires multiple passes for the water to become nutrient free.

[Murray]

The time is not all that critical. We have systems that cycle every 12 minutes and others that cycle every 50 minutes.
They each do equally as well.
Material that is not processed by the bacteria on the first round will be processed on the next round. All that matters is that the bacteria colony is balanced to the system.
It will take care of its self so long as there is water flow and plenty of oxygen in the system.
Oxygen is added to the grow bed for the benefit of the bacteria really well by the flood and drain action.

[Dufflight]

So with a large FT layering the GB's would save on pumping. And with one pump running all the time you could have the return going through a NFT before it gets to the FT. All this could help with the amount of water that needs to be pumped every hr.

[Murray]

Any water that goes to NFT needs to be free of solids to work really well, so your plan to use the water for NFT right at the end is good. Depending on your individual system the water might be a bit short on nutrients by then.

[Dufflight]

So far I've got 50kl of water with nitrate getting close to the 80 mark. Just waiting for the Nitrite to drop. Will have to see once everything is running better to see what amounts I can run.