is the such a thing as too low NO3 and PO4?

[cunry]

Ive been doing some reading and have been coming across contradictory statements. Everyone says you want NO3 and PO4 as close to 0 as possible but then I read if these two nutrients are 0 then the zooxanthele cant make food. so what is it? Im at 0 for both using salifert, should I start over feeding?

[tanked37]

Depends on the type of system you're trying to run, but NO3 and PO4 exists in every system and are just used up but things in the tank (ie algae, corals, bacteria etc). I would say from a detectable level especially for an SPS tank testing 0, 0 would be good. Just like there IS ammonia in the system that is consumed by bacteria rapidly and thus your test reports 0 the same is true for nitrates and phosphates.

[dkeller_nc]

In a nutshell, the answer to your question is "yes". You can read a number of threads in the SPS section about folks that have bleached/pale corals, and the general consensus is that one big cause of this problem is driving inorganic nutrients very low with carbon dosing/GFO/GAC/zeolites.