Backyard Aquaponics
A place to discuss aquaponics

Sorry Rupert you're right. This is info that is stuck in my head from my aquatic plant days. It is aquatic plants that prefer ammonia and nitrites to nitrates.




Totally forgot about the plants here. Good point. However, Live Rock and Deep Sand Beds are both filtration techniques that promote anaerobic areas that deal with nitrate removal. There are also Algae Turf Scrubbers and Macroalgae filters that are essentially saltwater AP systems that do a good job dealing with nitrates.




The trickle towers I am used to from aquariums and aquaculture are known for oxygenating the system as an additional benefit because of their 'trickling' effect. Of course large scale enclosed filters may be different. But as far as aquaria go people do usually refer to trickle towers/ wet-dry filters as nitrate factories.

No... IMO... turnover is important... for bio-filtration and oxygenation...

Higher flow rate/turnover may assist with oxygenation... and may acheive a "slight" increase in bio-filtration...

But ultimately the bio-filtration capacity is limited to the surface area inhabitable by the bacteria... in order to convert to nitrates...

High flow rate filters... such as Bakki Showers do acheive significant results in bio-filtration...

Or more correctly ... in terms of nitrification/de-nitrification... in as much as the highly oxygenated, high flow... effectively de-nitrifies the nitrates into NO2...

Hence their huge popularity amongst Koi keepers, and large aquaria enthusiasts... where the removal of nitrate is as much of a problem as ammonia conversion...

As above... one of the reasons many are abandoning "trickle towers"... is that they're pretty in-effective at nitrate removal... and not much better than other methods at bio-filtration..

You beat me to it Rupert. Right when I was ready to post you answered my question. So in your opinion it is the amount of media which limits the amount of bacteria (and in turn the amount of wastes used) as opposed to the flow rates and the 'feeding' of the bacteria?

Pretty much.... think enclosed RAS... or even aquaria... bead type filters... they're limited...or sized... to process according to the amount of media used... or more correctly the surface area available...

Other factor to consider with flood & drain growbeds... would be that flow rates are limited to the abilty to drain the growbed.. whether that be by siphon or overflow standpipe...

Either, but certainly in relation to siphons... are dependant on flow rate, both for drainage and flood level in the growbed...

Of course you could up-size your piping... but to what point... i.e how much of the growbed area are you prepared to devote to actually just having a drainage mechanism... and for what benefit...

Thanks for the help Rupert. You're really helping me make up my mind as I was thinking of changing my system (again). If I were to do it I would go with the bigger pump, bigger standpipe, bigger drain holes for quicker fill or more flow thru and for quicker draining.

The reason I don't want to just add growbeds (as would be the obvious solution) is that I'm trying to keep my system as small as possible. Right now I can't hold too many fish in my 110 gallon FT and the GB is sitting right on top of the FT. If I had to add on I would be taking up more space.

Your stocking density is going to be limited by the amount of bio-filter you have. Increasing flow through will only minimally increase your bio-filter and expecting such an undersized amount of grow bed to support twice it's volume is likely to overload the grow bed with solids and you probably won't have enough plants growing to pull out enough of the nitrates. If you stock heavily for the size of the fish tank, you will likely be teetering on disaster. You might manage more fish by adding additional alternative types of filters and removing solids but you will be increasing complexity in order to do it.

If you are wanting to stock a 110 gallon tank heavily, then you actually want 4 of those 55 gallon grow beds and a sump tank to do it the flood and drain grow bed way. Currently you are running 1:2 while max stocking wants 2:1
grow bed:fish tank.