Interesting thread folks. I think P is one of the main things folks need to be worried about, more then nitrogen really. The hobby goes where the so called experts and such wish to take it...good or bad.
When you are approaching P you have to understand it comes in various forms and types, some we have a chance on removing some limiting entry and some no chance at all. P as with most related element cycles through the various forms, thier are certain times and instances that we can jump in and break that cycle, if left unchecked it will just grow larger and larger.
Unlike nitrogen (nitrites/nitrates and so on) P is limiting, it can only enter your tank if you put it thier, where as nitrates can be made in the tank. So the best defence on fighting P is to limit its entry. This is all and good but impossible to do completely, so no matter what you are stuck with a small constant entry of it. And thus the battle to remove it begins.
heres a few concepts for ya.
We feed the fish, this puts in Inorganic P into the tank in both soluable and insoluable forms. the fish and bacteria will pounce on it and turn the insouable IP into organic P (gone) the small amount of souable IP we have a chance at by using a P sponge (such as rowa or phosban)so first kick at the can.
Ok back to out IP that turned into organic in a critter or bacteria. once in thier it is locked up until that critter releases it. So in the case of the fish a feww hours until it poops and with bacteri until it dies (which could also be a few hours). Ok the poop, the poop is Particulate Inorganic P (as it is not part of any critters matrix), and some Soluable IP. so another shot at the P can. Now a sponge such as rowa can remove the particulate IP just the dissolved version (so a little more is removed) for the particulate tha is where a product like carbon would come into play if used. it removes particulate matter so a bit more get removes. Ok so back to the journey or the P. the fish poop/detritus/extra food can be removed if any of these forms are removed from the tank (ahhhhh the beauty of a BB,, hehehe sorry I had to) if you remove any of those or all through skimming, carbon, syphoning or what ever you have completely removed the P in all its lovely forms with the exception of the OP which is bound to the matrix of critters and some dissolved forms being constantly pooped out by the critters. the dissolved form can continue to be removed if your sponge is kept running 24/7, (deals with it as it comes into play). the detritus/poop/extra food being removed removes both the IP bound in those materials but also takes the OP out throught he removal of the bacteria that are assoc. with it (sitting on and in it feedinng on it), remember those importal words "thier is nothing good about detritus just get it out". so if you combine the above methods you have a very good chance at limiting the input and maximising the output with out effecting the growth of the critters that need it.
On the products like rowa and phospban. Fluidising them is th best method for doing it (allows more surface area for absobtion) slow constant flow is best. I just made two 24 inch so called fluidised reactors at a DIY cost of 50 bucks for both, so not a big venture. They way they work is that so much of it will remove x ammount of IP from Y ammount of water, so running it fulltime is perfect, remember IP comes out when the critters dictate not you. Having the sponge available when ever that time comes is a good thing.
anyway I am not sure if that confuses things more, but the coffie intake is low at the moment.
Mike