Maybe I can muddy up the Phosphate thing for a few folks. P is in everything, so it is a very key player in the game of life. It is also a nutrient and a food for alot of things. As it relates to our tanks, Our test kits can only measure inorganic forms of P. Call it food that has not been eaten yet. The vast majority of P inour tank are in the form of organic. Call it food that is part of some type of critter, (bacteria/algae,nematodes, bound to argonite sand, everything really). Your reef tank is a very aggressive in regards to eating. bacteria/algae and so on will have massive population increase to keep up with the food surplus. If you get a reading of PO4 inorganic phosphate, it is telling you that your p is saturated to the point where in can not be bound by anything any more and thus it stays soluable in your water. To much P can cause all sorts of problems from algae blooms to not allowing corals to calcify (cant make skelitons) and so on. so we dont want to go thier.
Ok how does this work with a DSB. with a DSB you get hit 2 ways. One is that the sand itself comes into your tank fully bound with P, from its previous life. You put it in. Now as your anaerobic zone builds up, the ph level in the lower reaches of the bed goes down, as it goes down it melts the sand and thus unbinds the P that was once locked in it. The P upwells and is jumped on by both bacteria and algae. Which leads us to the second problem. Now if you take this P that is being freed with i the bed and then add the P we get from AS mixes, and foods and additives and so much more, we end up with a lot. Now what you end up with is a biological cycle. the bacteria that bind up the P have a population explosion, but as the P deminishes the bacteria end up starting to die plus they dont really have a long life span anyway (sometimes only 12 hours). anyway as they perish they release all the P and N that they have absorbed or eaten, this is immediately bound up by Vegitation, Usually Cyanobacteria, hair algae, and most other pest forms of algae. Now the same thing happens all over again, the algae blooms as the food source is available, until it begin to use it all up, them it begins to die and rot, when this happens the bacteria once again take advantage of the situation and begin to once again bloom. Anyway it is a never ending cycle, that only gets worse with the addition of foods everyday.
On Rob Toonans tank you must keep one thing in mind, his tank has a very very low bioload and only contains corals that love a nutrient rich enviroment. Also from what I understand, it was broken down in the middle of that run of time.
Hope it helped
Mike
:smoking: :LOL: 
