Is more really better? Filter turnover.

[ewurm]

So a wet/dry @250gph vs. one @500gph over the same volume of media is more effective, because of the longer dwell time?

No, the dwell time is the same in wet dry.

 

[Danyal]

i don't think that the UV sterilizer/filter flow is a very good comparison. in a UV filter you have to make sure that the flow won't carry the organism past the bulb before it has recieved enough UV light to kill it. in a bio filter you're trying to carry more oxygen to the bacteria. the bacteria act like sponges and absorb the nutrients and oxygen from the water. because the nutrient levels are going to be the same in every part of the tank(you won't get nirtates in one corner and no nitrates in the opposite corner, not enough volume) except coming out of the filter. the more oxygen in the water the more bacteria it can support and the water entering the filter will have more oxygen than the water exiting the filter, except with wet/dry filters, so more flow means more oxygen being carried to the bacteria. in sunpoe's example filter A will be able to support more bacteria in an equal amout of volume than filter B because it is providing more oxygen than filter B, living organisms will multiply until they reach the limits of the ability of their enviroment to support them. so if filter A provides 20% more oxygen then it will have an equivalent amount more bacteria than filter B regardless of volume and will be more efficent than filter B.

 

[vanimate]

No, the dwell time is the same in wet dry.

wurm, if the water flows twice as fast over the media and bacteria , than isnt the dwell time halved?

 

[aquanaut]

wurm, if the water flows twice as fast over the media and bacteria , than isnt the dwell time halved?

It will also pass through the media twice as often.

Any flow above the rate to keep the parameters at 0 is simply a waste of energy(electricity) JM2C

 

[rottbo]

I usually go on turnover rate but how much depends on the size if the tank and the inhabitants.. some tanks I turn over 3 times an hour some I turn over 12

 

[marcos]

man this is really interesting I never thought about this, on my 90 gallon I have 3 filters 2 of them are piped into fluidized bed filters at a flow rate of about 150 gph because if I turn it up the sand will get pushed out and I also have another small filter to power my uv @ 100 gph this is only a turn over rate of this is only a turn over rate of 3.8 x ph but this tank is lightly stocked and I have never had a problem with water quality so does anyone think that the above setup is better then if I had different filters with a much higher flow rate?

 

[Danyal]

if your parameters are where you want them then why spend more money on a better filter when you've already got good water quality? unless you're upgrading to a filter that will use less energy or are getting ready to increase your bioload or have a fish that needs a tank with lots of water flow(i.e. something that comes from shallow fast flowing water) some reefers use sumps or filters that only have a turnover of 2 or 3x but because their corals need more flow and to keep the waste suspended in the water so it can be removed they add powerheads that are cheap and use little engergy or even mod a powerhead(even heard of a maxi-jet mod? aprox. 2,000gph, uses only 21w and costs about $40)
in my 29g i've got a fluval 3plus(internal filter) that does a great job but because all my fish, danios loaches and white clouds, come from fast moving streams i'm going to change to a sump and aim for a 12~20x turnover. in my 10g BW tank i've got about 300gph because i have roughly 15lbs of live rock that traps debris and creates dead spots.

 

[Dr Joe]

So a wet/dry @250gph vs. one @500gph over the same volume of media is more effective, because of the longer dwell time?

Yes

.

This is a very interesting topic. I personally believe a filter is not the only thing harboring beneficial bacteria, thus the turnover rate is not as important as the overall water circulation in the tank. I have recently completely cycled a 55 gallon community tank using no filters at all. I have two power heads for water circulation and two old pieces of driftwood and gravel. In less than 6 weeks this tank did everything that my well filtered tanks do except they dont have any type of mechanical filtration. The ammonia, nitrites, and nitrate all came and went as if done with usual filters. I currently have 6 tri-color sharks, 6 tin-foil barbs,4 convicts,4 assorted little catfish,redtail shark, and 10 giant danios. All these fish are small. I just completed my first water change and all is well. Aside from needing to vacuum the gravel often the water quality is excellent.


I agree that you generally cannot have to much filtration and flow, but i also have proven you can go filter-less and still achieve good water conditions as long as your not overstocked and over fed.


I think the best of both worlds is moderate filtration and moderate flow, and more importantly keep up on those water changes.

JMO

bob

Welcome to the 1920's.

.

No, the dwell time is the same in wet dry.

No

.

i don't think that the UV sterilizer/filter flow is a very good comparison. in a UV filter you have to make sure that the flow won't carry the organism past the bulb before it has recieved enough UV light to kill it. in a bio filter you're trying to carry more oxygen to the bacteria. the bacteria act like sponges and absorb the nutrients and oxygen from the water. because the nutrient levels are going to be the same in every part of the tank(you won't get nirtates in one corner and no nitrates in the opposite corner, not enough volume) except coming out of the filter. the more oxygen in the water the more bacteria it can support and the water entering the filter will have more oxygen than the water exiting the filter, except with wet/dry filters, so more flow means more oxygen being carried to the bacteria. in sunpoe's example filter A will be able to support more bacteria in an equal amout of volume than filter B because it is providing more oxygen than filter B, living organisms will multiply until they reach the limits of the ability of their enviroment to support them. so if filter A provides 20% more oxygen then it will have an equivalent amount more bacteria than filter B regardless of volume and will be more efficent than filter B.

The comparison wasn't between UV's an dfilters, just stating that they both need dwell time.

Yes more flow means more nutrients (ammonia is what we are concerned with for this conversation) to the bacteria.

'B' is more efficient...more area for bacteria to populate, longer dwell time for bacteria to break down ammonia...All ammonia is not used up with each pass thru the biological material and a higher flow rate increases this factor (by shortening dwell time)

If bacteria have enough 'food' they will increase their population to the area provided and stop growth, if bacteria starts growing on top of other bacteria the bottom bacteria will die off for lack of 'food & oxygen'.

.

wurm, if the water flows twice as fast over the media and bacteria , than isnt the dwell time halved?

Yes

.

It will also pass through the media twice as often.

JM2C

The bacteria have a set time it takes to break down the ammonia, decreasing dwell time (higher flow rates or passing it thru twice as ofter) is a waste of time and power (unless you have very high detrious levels).

.

Dr Joe

.

 

[Bgonz]

.



Welcome to the 1920's.

.

{Quote}



I'm a little behind the times



bob

 

[WeeNe858]

the only reason your tank "cycled" Bgonz is because of the surface area in your tank. but if you broke it down and thought about it.. your tank would only be able to hold about 1/3 or less of what your tank was inteneded with a filter because of the lack in bacteria. filters are ushually dedicated to hosting the bacteria and the media use for that contains alot of surface area thus keeping the tank stable

Bacteria without filter |------------------|
Bacteria with filter |---------------------------------------------|
(note graph is not drawn to scale)