Nitrate question?

[snakeman2198]

Hi gang,
I have a 120g mixed reef and my nitrates were @ 40ppm. I did a 30g water change on Sunday and it brought it down to 20ppm. My question is, how often can I do a 25% water changes to get it down without causing problems?
I don't know if I do too much or too often if it will trigger a cycle change. The tank has been running 18 months since it crashed. Prior to the crash it was up for over 5 years.
Thanks for any advice

 

[oscarreef]

You can do as many water changes as you want as long as the temp, salinity and ph levels match your current water. The cycleing bacteria is on the rocks and sand so no need to worry too much about that. My tank was 50% water changes once a week. Some nano tanks do 80% just make sure the levels match.

 

[DRThompson]

Oscarref is correct; nitrifying bacteria live on surfaces (i.e.: glass, rocks, sand...etc). You can do large, frequent water changes without worrying about killing off the bacteria. Frequent changes in pH, salinity and temperatures can be stressful to your fish so take care to match up those readings at each water change.

If you experience a "bacteria bloom"( i.e.: cloudy water with ammonia spike that seems to happen overnight) this is not caused by the nitrifying bacteria. This can be caused by a high concentration of organic matter in the water. It can be triggered after a water change if you stirred up a lot of detritus during a water change. Frequent water changes, protein skimmer, chemical filtration, filter socks or floss will all help prevent it.

 

[snakeman2198]

Thanks for the helpful info ��

 

[mpfeiffer1]

As Dr T and Oscar mentioned -Water changes can lower trates but I would suggest you look at the "why are they high". Usually the cause is a large bioload, over-feeding or lack of nutrient export from frequent water changes, large skimmer or macro algae. My suggestion is to feed less with the highest quality food (no flakes), check your bioload, and get the largest skimmer you can. You may also want to look into carbon dosing. Good luck!