Nitrate Vs Phophate

[maroun.c]

Which would you think is the more harmfull one to SPS?
AFAIK Po4 will stunt growth and might cause corals to brown out. is nitrates the same or is it more harmfull what are the effects of nitrates and at what levels do phosphates and nitrates become lethal to SPS?
Thanks

[serpentman]

IMO both are important in very low concentrations. However in higher levels, they each have negative side effects.

High PO4 levels will promote overproduction of zooxanthellae which will effect color resulting in browning. It will also encourage algae which can adversely effect SPS. I am guessing that lethal levels of PO4 wouldn't necessary kill corals directly but cause algae blooms and associated anoxic conditions aka red tide, etc.

However, NO3 in higher concentrations can actually adversely effect the coral's growth directly and eventually kill some specimens.

Therefore, I would say in aquarium conditions, PO4 is the lesser of 2 evils. However, on an actual reef, PO4 via pollution, etc. would be the element more likely to cause widespread deaths.

[ReefTECK]

PO4 is an active inhibitor of calcification and as shown by studies (I don't have time to find the reference) is known to be inhibbitive at .05ppm.

NO3 can actually increase the rate of coral growth (there is some debate about this)....up to a point, these should not exceed 10ppm in a SPS tank IMO

Originally Posted by serpentman

I am guessing that lethal levels of PO4 wouldn't necessary kill corals directly but cause algae blooms and associated anoxic conditions aka red tide, etc.

PO4 is the lesser of 2 evils.

I respectfully disagree, based upon the fact that PO4 is a KNOWN inhibitor of the calcification process and leads directly to the death of SPS corals, and that is the context in which we are speaking. I think most will support PO4 is a much greater threat.