ok now that I am rested, back on topic. I was exhausted last night and could form coherent thoughts. except to laugh at the frodoness of the conversation....
keep in mind I'm not fully awake yet coffee is still brewing in the pot. I may overlook a fact of two in my coming post, be gentle.
I have noted an increase in skimmate during dosing vodka, this is apparantly in relation to the increase in heterotrophic bacteria which requires nitrate and phosphate to sustain itself along with carbon. the skimming then removes a portion of the bacteria which is the goal, get it to form trapping the nitrate and phosphate in its structure, then remove it via skimming. (the basic principals of vodka dosing) a very similar line to useing macro algae, grow the algae so it utilizes nitrate and phosphate in growth then when the mass gets large harvest thus physicly removing the consumed nitrate and phosphate providing room for the macro algae to grow again. if you remove too much mass though you may not have enough macro algae to consume incoming nitrates and see an elevation of nitrates untill the biomass and growth rate again catches up to the influx.
about the only methods that differs from these types of "grow and remove" nitrate reduction would be DSB's because there is no physical harvesting involved. the DSBs provide an area for anaerobic bacteria to grow, which completes the often incomplete nitrogen cycle in our tanks. its amazing to see how often hobbyests even expirienced hobbyests say the nitrogen cycle is: organic material to Ammonia to nitrite to nitrate. and thats it. thats actually not it. it just happens to be where it ends (incompolete I might add) in most tanks that arent set up to denitrify.when in fact the complete cycle is: organic matter to ammonia to nitrite to nitrate to nitrogen gas (this is simplified a bit as it pretty much skips the stages various stages of anaerobic digestion) but the nitrogen gass then bubbles up through the DSB to then rise to the surface of the tank and off gass into the atmopshere. the rising nitrogen actually displaces water moving it from the lower regions of the aerobnic layer where almost all the oxygen has been depleted further down into the anaerobic layer feeding fresh nitrate from the aerobic layer. thus the cycle is completed. at this point IMO a DSB is one of the best methods of nitrate removal available to hobbyest as its pretty much maintinence free, once you set it up as long as your aerobic layer stays aerobic the cycle will complete itself. with less effort by the hobbyest.
water changes: pretty straight forward, when done correctly water changes remove both the by-products (nitrate, amino acids etc) and some of the source the organic waste before it breaks down along with the gelbstoff. the relation of amount of nitrate remeoved is in direct relation to the amount of water changed. AKA a 25% water change will reduce existing nitrates by 25% IT WILL NOT however necessarily remove the same amount of source organic matter so in a very short time the nitrates can re-elevate to the same level IF the source isnt removed as well.
skimming: this comes in handy for helping to remove the source. foam fractionators (skimmers) use microbubbles to attract hydrophobic materials to the bubbles and transport them to a cup to be deposited. such hydrophobic materials include, protiens, bacteria, calcium and various other elements, particles of foods, microfauna and more. getting some of these out before they get to break down through the nitrogen cycle reduces the influx, thus reducing the end results. IMO a skimmer should be consideredd a staandard piece of equipment on a tank.
algal filters: this is similar to macro algaes but a different set up, same concept, grow algae, harvest algae nitrate removed. you can have hours long converstations on how to set these up but the function couldnt be more basic.
