[Witfull]

I have noticed a bit of pendulum swinging lately regarding substrate use. FWIW I still like sandbeds used as biological filters. The one point that Dr. Mathews missed (and it is just a brief mention in the margin in TRA3) is that biological filtration in sandbeds is not just nitrogen cycle management. It also involves the destruction (by microorganisms, including bacteria) of toxic substances produced as chemical warfare by various corals, other invertebrates, plants, and bacteria. This function is what helps PREVENT old tank syndrome. It is the failure of this function (when the sandbed becomes plugged up) that leads to problems. Ah yes, I know you are waiting for that article- coming soon!

Julian Sprung

Julian discussed this at IMAC 2005. unfortunately i ddint attend. hopefully i will be able to talk to him about this at MACNA. (or possibly sooner)

in other conversations with reefers, they have been doing what they always have, but have seen a "decline" in their tanks.

thoughts, DSB care, build up of mulm deep in the bed slowly preventing biological processes. loss of varied micro organisms. clogged rock with mulm.

i think it is possible that OTS is not triggered by any one thing. but multiple factors that in the right condititions cause OTS. you cannot deny that PO4 gets bound in rocks, and it can leach back into the system. water can test perfect yet, problems occur.

anyone who has "cooked" LR has seen the amount of mulm and diterus thats shed. having had BB tanks for many yrs i know my rocks would shed, but when cooking the amount is far more than than normal sloughing.

DSB's are not the wonder tool they were originally made to be, they need attention. and i would hypothisize that sands need a vigorous cleaning as well. this may not be easily accomplish and partial sand replacement may be the better option. systematically removing a fraction of the bed and adding new to that area, then move on to a new section at a later date.