Hello everyone,
Thank you all for talking about this topic so openly - I truely appreciate it. When I try to discuss this topic with Aquascaper types they get angry and wag their fingers in my face and shout; "This stuff doesn't matter! Nobody cares about this!" So, from the bottom of my heart, thank you all for caring about a topic that is so vitaly important.
I created this thread in answer to a basic question I recieved on another thread about what is SSA? So my anwsers were basic questions of what SSA is. I am happy to see that the discussion has expaned to included methods of measurement and what effects SSA and biofilm growth.
I never fake injuries. If ever there are "holes" in my data, I want to know about them and correct them. My love for learning will never end, and I'm never ashamed to admit that I don't know everything. I'm always will to learn. I never run, I never hide, and I never fake injuries. I learned how to swim by falling into the "deep end" of the pool - and even though I was in "water over my head" - I soon learned how to swim.
SSA is vitaly important to all aquaculture systems, but sadly there is a lack of information about it and virtually all web sites gloss over its importance. For example on this web site:
http://www.pskoi.com/about_koi_ponds.htm 6th bullet down. The only referance to filtration states:
Use the appropriate amount of filtration, based on water volume and keeping in mind the amount of Koi you would like to stock - more Koi=more filter (there are many types of mechanical & biological filtration systems)
This is a highly respected web site of a highly respect company that provides the highest quality of service and products - but a person reading this web site would not know how to size a filtration system based on the information provided. This is common all across the internet and in koi shops, and ponds shop around the country. SSA is a critical number that helps answer the questions about filter size.
I had a request asked of me on another thread to shed some light on what SSA is. My thread here was a basic description of what SSA is and why it is important in figuring filter size. I see now that the thread has been expanded to include measuring methods and what can effect SSA. Fantastic!
For the discussion I listed a handful of the most common types of biomedia. Pads are popular, and bulk types is popular - but pads are typically listed in square feet per square foot at their thickness. Bulk media like beads and honeycombs are usually listed in cubic feet. So I could have converted pads to cubic feet, or convert bulk media to square feet - I simply chose the latter.
The world market is primarily metric, the US is not. So for the sake of the discussion all metric measurements where converted to US standards. Also, all objects with mass have measurable surface areas - including 3 dimensional items. This link is an example of geometic equations for calculating surface areas of 3 dimensional objects:
http://www.math.com/tables/geometry/surfareas.htm
Most filter pad SSA is typically measured at 2" thickness. So a filter pad SSA is measured per square foot at 2" thick. Bulk media is typically measured in cubic feet. To compare the SSA of bulk media to filter pads - simply divide a cubic foot by 6 to get 2" thick. This allows "apples to apples" comparison of nothing more that SSA.
Kaldness. Great product. I listed the SSA of Kaldness at 41. That is 41 square feet of this bulk media per square foot 2" deep.
http://www.evolutionaquaculture.com/p_kaldness.html publishes Kaldness SSA of 800 meters square per cubic meter. Here is how I converted it.
The following link is a conversion calculator:
http://www.metric-conversions.org/ar...quare-feet.htm
1 square meter = 10.76 square feet
800 square meters = 8,611.13 square feet
http://www.metric-conversions.org/vo...cubic-feet.htm
1 cubic meter = 35.31 cubic feet
8,611.13 square feet per 35.31 cubic feet.
Divide each by 35.31 to convert to one cubic foot.
8,611.13 / 35.31 = 243.87 square feet per cubic foot.
Divide 243.87 cubic feet by 6 to convert to 2" deep square foot.
243.87 / 6 = 40.65
For the discussion I rounded up to 41. Kaldness has approximaely 41 square feet of surface area per square foot block 2" thick. This enables us to compare the surface area of Kaldness to the surface area of 2" thick filter pads. You can also mutliply the SSA of 2" filter pads by 6 to convert their SSA to cubic feet. A filter pad with SSA of 49 at 2" thick per square foot would have an SSA of 294 per cubic foot.
Steve is 100% correct on detritus being a biofilm growth inhibiter. The primary nitrifiers are Nitrosonomas and Nitrobacter bacterias. These strains consume chemical compounds only (ammonian and nitrite). These are slow growing bacteria that reproduce by seperating or "dividing". They double in size, on average, every 15 hours and require chemical rich, highly oxygenated water to stay alive and multiply.
Heterotrophic bacteria strains are carbon eaters. The dominate strains are of the Bacillus family that primarily include subtillis, licheniformis, amyloliquefaceans, megaterium, and brevis. These bacteria strains produce enzymes including Protease, Amylase, Lipase, Esterase, Cellulase, Xylanase, and Urease that break a variety of protiens, fats, and carbohydrates down - but are not effiecient at ammonia.nitrite removal. These strains rapidly reproduce by spoaring and double in size every hour. They too rely on heavy amounts of oxygen.
Detritus is a carbon-based organic waste byproduct of the nitrification cycle in biofilters. Detritus inside biofilters provides food sources for the rapid-growing heterotrophic bacteria strains. Doubling in size every hour, they quickly out pace the growth of the nitrifiers that are in the biofilter and out compete for the available disolved oxygen - thus lowering the effiency at which a biofilter can metabolize the chemical compounts - ammonia and nitrite - which is the primary function of biofilters.
SSA is simply a media surface area mesurement - it is not a biofilter efficiency gauge. When talking about biofilters themsselves - of course keeping the media free of detritus is absouletly essential.
Any biofilter should be backflushable to remove the detritus. Russell Watergardens is the only manufacture of filtration units for the water gardening industry that incorporates this. What all of you have known for years - we put into every one of our filters.
Steve, you are correct again with regards to "open space" within bio-media. As agreed upon above, Nitrifiers require a steady stream of highly oxynenated water. Media that is too dense, while having higher surface area, restricts the passage of oxygenated water - quickly clogs, and water then starts "channeling" around the media. This causes anaerobic zones within the media that can cause aeromonis outbreaks.
We are in agreement so far, if I'm leaving anything out please let me know.
Now, you brought into this thread the dreaded R&G arguement.
So lets address it. Surface area of gravel can be calculated fairly accurately by measuring each piece of gravel the same way you would measure the surface area of individual beads. Going back to the geometry web site:
http://www.math.com/tables/geometry/surfareas.htm we see that we can use the formula of calculating the surface area of a sphere to get pretty close to that of smooth rounded rock. 4 x Pi x radius squared. Let us calculate the surface area of a single 3/8" piece of round pea gravel.
3/8" diameter = .375" diameter
radius is 1/2 diameter. r = .1875"
Pi = 3.14
4 x 3.14 = 12.56
r squared = .0352"
4 x 3.14 x (.1875 x .1875) = .4421 square inches of surface area per 3/8" rounded piece of pea gravel. There are 2.67 individual pieces of 3/8" gravel per inch. There is 144 square inches per square foot. 144 x 2.67 = 384.48 individual pieces of 3/8" gravel per square foot at 3/8" high. There are 2.67 individual pieces per inch, two inches is 5.34 piece deep, so multiply 384.48 pieces x 5.34 high to get how many pieces of 3/8" gravel there are per square foot at 2" thick. 5.34 x 384.48 = 2,053.12 individual pieces. Multiply that total by the square inch surface area of each piece: 2,053.12 x .4421 = 907.68 square inches of surface area per square foot at 2" thick. Convert to square feet by dividing by 144. 907.68 / 144 = 6.3 square feet of surface area per square foot at 2" thick.
Bare liner has a surface area of 1 square feet of surface area per square foot. 3/8" pea gravel has 6.3 square feet of surface area per square foot at 2" thick.
(You can do the above calucutaions with 1/2", through 8" gravel and take averages if you like - but for this discussion we're keeping it to 3/8" gravel)
We have all agreed that a pond should have a skimmer that pulls water out of the pond, and water should be fed back to the pond with jets, fountains, or waterfalls of some type. Ponds without gravel should have bottom drains, ponds with gravel shouldn't because they'll clog with the gravel. We all agree that the pond should have submerged aeration. All the ponds we are discussing have koi in them.
In ponds with the above mentioned features - the water is not stagnent. Water currents are made from the pond skimmer pulling water across the top, water jets, fountains, and/or waterfalls that introduce water currents and ripples. Submerged aerators circulate bottom water upward as the air bubbles pull water upward as they rise. Now add koi swimming around pushing water in all directions. All this leads to water moving across the bare liner, as well as gravel covered liner. Does all the water in the pond pass over the gravel - certainly not, but it is not stagnent. So we possitively can add the surface characteristics - at least partially - to the total surface area of the pond.
(For an easy visual test to prove this - use an eye dropper to place a drop of food coloring anywhere on the pond's surfaces below the water line and watch where the dye goes - it doesn't stay still)
Now in all my threads, you know that I absolutely positively state that if your going to have gravel -
it has to be kept clean - or don't use it. I am consistant on this.
It was also mentioned in this thread that stiring up gravel releases harmful gasses and organics into the water. Yes, you are correct - no arguement there. The
AMOUNT of gasses and organics is extremely small and not harmful when cleaned on a monthly basis - 1/4 of the ponds' gravel every week. I am not talking about doing this to the "once a year cleaned ponds" of the Aquascape variety - I am talking about how aquariums are kept clean without harming the fish inside.
An additional method of protection could be the use of a pond vac for this type of gravel cleaning. "Fluff" the gravel with a water jet infront of the suction hose of a pond vac. The "soiled" water can be removed easily and not introduced into the pond at large.
Once last comment was made regarding show quality koi and rocks & gravel. I am on redord as saying "I, and Russell Watergardens do not recomend koi that are to be grown and raised for the purpose of showing or competing be kept in any pond with objects that could cause physical harm as a result of collision - rocks includled." You have no arguement from me.
Again, thank you all so much for taking an interest in this topic. If I have left anything out, or incorrect data, please tell me so that I may improve my knowledge.
It is my honor and privilage to learn from you all.
Sincerely,
John Russell
President/CEO Russell Watergardens