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RFF Biology Question
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Author:  moiz [ Apr 7th, '18, 19:38 ]
Post subject:  RFF Biology Question
I want to have a clearer understanding of whats happening in my RFF.

this is my understanding of it so far - please correct me where i'm wrong...

the solids in rff give out ammonia (which goes into the water?)
the ammonia-rich water travels onto the gravel beds where bacteria living on the gravel convert it to nitrites and nitrates.

if above is true, should the solids in rff eventually stop giving out ammonia and become dormant/harmless?
Author:  Mr Damage [ Apr 7th, '18, 20:01 ]
Post subject:  Re: RFF Biology Question
moiz wrote:
the solids in rff give out ammonia (which goes into the water?)?
Some, but very little in the scheme of things. Most Ammonia is given off by the fish through urination and respiration.

More importantly, the fish waste solids contain all the mineral elements that are essential for good plant growth. The solids should be regularly collected from the RFF and treated in a bio-digester to liberate as much of the mineral elements as possible. This nutrient rich water is then added back into the main system.

If these mineral elements aren't liberated from the fish waste solids and simply discarded, then you will definitely run into nutrient imbalances (ie: Too much Nitrogen in ratio to mineral elements) and general deficiency issues.

Quote:
if above is true, should the solids in rff eventually stop giving out ammonia and become dormant/harmless
The opposite... If left to accumulate in the bottom of the RFF for too long they can become anaerobic and if disturbed they will give off Hydrogen sulphide, which can kill fish very quickly.

I had a customer disrupt and anaerobic pocket in the GB of his system while removing a long established plant, the water was still flowing through his system at the time and his fish started dying within 20 minutes.
Author:  boss [ Apr 7th, '18, 20:07 ]
Post subject:  Re: RFF Biology Question
Mr Damage beat me to the answer, lol!
Good question: While it's true solids in the RFF (radial flow filter) give off ammonia that isn't the purpose of this device. The RFF separates solids and they fall out in the bottom. The idea being that these are excess solids which produce excess ammonia. There is still plenty of ammonia in the water which will be transformed by bacteria in the media beds to nitrites and then nitrates.
Here are couple of drawings off the Web that show how the solids fall out.
Attachment:
Internet-RFF.jpg
Internet-RFF.jpg [ 35.62 KiB | Viewed 3547 times ]

Coincidentally the above drawing shows bioballs around the top of the stilling well (that cylinder which separates the waste water moving up from the bottom from the clear water which will move on to the media beds.)
Attachment:
Internet-RFF-SLO.jpg
Internet-RFF-SLO.jpg [ 106.38 KiB | Viewed 3547 times ]

I hope this helps
Brian
Author:  moiz [ Apr 9th, '18, 06:52 ]
Post subject:  Re: RFF Biology Question
I currently have a conventional blue barrel solids filtee but im thinking to put a seperation mesh into it, some bio balls into the water above the mesh and then run an air stone into it
Will this prevent the anearobic problems damage mentioned and allow me to clean my rff less frequently?
Author:  scotty435 [ Apr 10th, '18, 04:00 ]
Post subject:  Re: RFF Biology Question
Probably not.
Author:  skeggley [ Apr 15th, '18, 07:54 ]
Post subject:  Re: RFF Biology Question
I decommissioned my filter because I couldn't be bothered cleaning it as often as I should have. Letting the solids sit will, as mentioned earlier, cause anaerobic issues. One is that the pH will be driven higher.
Author:  Know expert [ Apr 16th, '18, 04:48 ]
Post subject:  Re: RFF Biology Question
Hi Moiz, unless I misunderstood, I think that adding an air stone would cause any solids to be disturbed and therefore it would defeat the object.
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