Ok here is my math on Bio Media - Argument against pot scrubbies.

[VLDesign]

There's also no value in the formula for the substrate, plumbing, etc ... that is also a factor in the total biological filtration.

Yes you are correct, but at the moment this is being factored in as negliable as to try to get a good basis for a solid formula as to how much media would be considered enough.

After that can be established I am sure the substrate (Sand in my case) and the plumbing will only add to the effiency of the overall system.

 

[cchhcc]

Regarding the last two posts:

LiquidWare: Good post..... In central systems, the "wet/dry" effect of water in the main drain lines (that are only partially filled) contributes a great deal to the overall nitrification process.

johnptc: Yes, less water is moved through the filter at one time, but the bacteria is able to more completely nitrify the waste. Think of it like a mechanical filter. A lot of flow through a porous mechanical filter would eventually capture most of the particulate material, but a slower flow through a nearly non-porous filter would only need one pass for each particulate.

 

[VLDesign]

I disagree. You cannot post an accurate and specific calculation when the primary variable is not calculable. Therefore, it seems there is no "starting point" for your hypothesis.

In your second example (1 to 3 waste production ratio), you must account for the types of waste and their degradation times. For instance, fish do not produce anything near to 1:3 in solid waste, but they do produce ammonia, etc. from respiration and other metabolic processes.

Also, there is no value assigned to various filtration methods (e.g. wet/dry is more effective in the same area as submerged), dwell time, etc. In your example of 4000 GPH, you will not achieve high nitrification rates unless the biomedia takes up a great deal of space. A lower flow, and longer dwell time, would produce better results.

Interesting discussion...

After finding this new formula I would now agree with you and would like to retract my media/gallon opinion.

Yes on that site is a forumla for determining ammonia rates and how fast the media can handle it. For sheer simplification of trying to do the right thing I am trying to focus on one aspect for now. Perhaps I will apply my logic to all of their formula and see what I come up with.

And wet/dry, submerged is all part of the question.... I am still looking for something that does a side by side comparrision of a true wet/dry vs submerged (Same media) test and proves one is better then the other.

As for interesting? Oh yeah it is. Good to see so many people getting in on this with valid points and new methods of looking at the same problems we all have. How big should I go.. lol

John already asked about the flow/dwell time. So I will stick with him on that question.

 

[cchhcc]

As far as the wet/dry vs. submerged study goes, I can't think of one. Anecdotally, though, I do know that a given amount of media in a wet/dry will support more fish than that same amount in a canister.

I bet if you search long enough, you'll find a study..... Heck, you can find just about anything on the net if you look long enough!