Nitrates wont go down even after 4 water changes!!!


I added 5 new fish to my tank within a 2 week timespan(1st mistake). I notice now my trates are about 80... i have done 4 30% water changes since noticing and no drop !!! I have a 125 fowlr setup running a wetdry, skimmer, ls and 80lbs of lr. tank has been running for years!!! I have stopped my skimmer from running for the past 2 weeks and also removed alll carbon,, and chemipure from the wet dry since im treating the whole tank with melafix!!! Do u think the discontinued use of carbon and skimmer caused the spike------- if so would 4 water changes knock it down,,,,,, since 4 30 gallon water changes = the complete copacity of the tank!
Thanks in advance with any feedback!!


I would put fresh carbon back in restart your skimmer don't do anymore water changes you just shocked the whole system I would also top off with store bought water ( 10 Gallons) wait overnight and check your parameters


Well-Known Member
As I understand it you have a tank that has been running for years and recently added fish and got a nitrate spike in a couple of weeks or so?
Actually there may be a highly technical and known only to advanced phd reef geeks with minors in astro physica and nuclear engineering.
it's call
ta da
wait for it
----- Normal!!!!!!
What may be happening is your mature tank (with algae on live rock or in a refugium) is consuming the increased ammonia directly and forgoing nitrates for nitrogen. Hence no ammonia spike but an initial and temporary nitrate spike.
if that is true it is actually a good sign of a stable tank doing it's thing. And in a few weeks as bacteria build up, nitrates will drop down when the algae is ammonia starved and starts consuming nitrates again.
So to me as long as the tanks looks healthy and the fish are active. I would just wait it out.
But that's just my .02


Active Member
bob said it perfect.80 nitrate though it seems high wont kill fish.imo around 150+ then start to worry.i have always had 20-40 on test and dont drive myself nuts to get it to zero.never had a fish or coral die over it.perfection keeping the ocean in a little cube is damn near imposable