W/D vs Sump

[X24]

Well i've heard contridicting stories about which is the best. I always thought W/D is better, but lately people have been telling me how they've had better results with a plain sump and really it makes some sense since with a w/d bacteria has less water contact time and a lot of the surface area of the biological filtration might not even come in contact with the water.

So whats your opinion?

EDIT: wasn't sure where to put this....i'm thinking setup and filtration would have been a much better option, but i guess its up to the mods to move it now.

 

[Dr Joe]

This doesn't go up for opinion, you have to compare apples to apples. I'ts all science.

Water flow is usually similar in both systems so most water is contacting bio-media with a properly designed drip plate. Not all water contacts the bio-media on every pass no matter what system you have.

W/D systems better aerate the water and allow offgassing over all the unsubmerged media, whereas a standard sump only has the surface area of the water to work with.

Dr Joe

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[X24]

W/D systems better aerate the water and allow offgassing over all the unsubmerged media, whereas a standard sump only has the surface area of the water to work with.

Dr Joe

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Could you better explain? I know it allows an air contact time, but the bacteria don't need that much oxygen to do their job, plain levels work perfectly for them, so why does adding more air to it along with long periods of only air contact make w/d so much better?

 

[Wolf3101]

Actully bieng exposed to the air makes the BB FAR more efficiant. They also react a lot faster to changes in the tanks bio-load.

Theres another factor you have to concider as well.... submerged BB draw O2 from the limited amount available in the water...thus reducing the amount available for the fish. With a true wet dry system they draw O2 directly from the air leaving the water better saturated for the fish.

 

[fishdance]

I made a flushing sump which does both but as long as your getting the water quality you need then use the one you like best.

 

[Dr Joe]

and I was speaking of aerating for both bacteria and the fish.

 

[Dr Joe]

I made a flushing sump which does both but as long as your getting the water quality you need then use the one you like best.

For F/W or S/W?

 

[X24]

Actully bieng exposed to the air makes the BB FAR more efficiant. They also react a lot faster to changes in the tanks bio-load.

Theres another factor you have to concider as well.... submerged BB draw O2 from the limited amount available in the water...thus reducing the amount available for the fish. With a true wet dry system they draw O2 directly from the air leaving the water better saturated for the fish.

hmmm any source for the first part?

All of this data is nice, but i've seen results of people submerging their media and making a w/d into a normal sump and coming out with better results (as in they had measurable amounts of ammonia and nitrite and afterwards they had unmeasurable amounts)

I'm really leaning towards just making a sump for my 150 when i get it and loading it up with a section of poly fiber, a section of scrubbies, a section of ceramic rings, a section of duckweed and hornwort and finally one for heaters and the pump.

It seems it should be quiter and unless i see the scientific data in my opinion it might work just as well if not better.

(no offense to either you are joe, but i've just seen results and i can't think of any other reason for them then maybe w/d's aren't as good as once thought)

 

[Wolf3101]

And I can post results to show that a sealed pressure system with no air contact other than the serface of the tank works extremly well....

Its a question of designing the system properly to take advantage of its strengths while reducing it's weaknecess. In general a true wet dry system will require a larger amount of media in a free flowing configuration. They work best in a tower arangement. If you converted a wet/dry sump to a wet sump of the same size it would hold more media of a smaller type and have a larger serface area.

That said...you can never HAVE any more BB than your fish load can support so if the readings in the tank improved it was because the former wet/dry system was inadiquate for the tank...not because it's less efficiant or not as good. Wet systems will still draw O2 from the collective pool in the water unless it's a wet/dry system.

 

[Dr Joe]

No offense taken, but without the data being pure (systems you saw and and a test system plus a control unit all set up in a controlled environment) it's hard to say why the system you saw started working better.

Your example just raised the water level in the sump to cover the bio-media right? Nothing else was changed, right?

The system your suggesting will work, don't put a thick layer of poly-fil as it will compact and not flow, just clean regularly.