HELP nitrates spiking

[jimnlee]

I am actually asking this for a friend who is unable to get online right now. He has a 42 gal. bowfront with a wet/dry and skimmer in the sump. His tank has been set up for about a year but for the last half of the year, his nitrates are spiking approximately every 2 months (it's happened 3 times). His ammonia and nitrites always remain at 0 and NORMALLY his nitrates are around 20 ppm. When the spike occurs, it's usually overnight and will go from 20 ppm to as high as 160 ppm.
Any ideas what could cause this? I forgot, his bioload is:
sailfin tang
coal beauty
percula clown (until last night, died due to the nitrate spike)
yellow wrasse
cleaner shrimp (also recently deceased)
cc star (ditto)
emerald crab
When he noticed the spike, he did a water change (25%) but the nitrates remained high.
Thanks in advanc for your help and suggestions.

 

[rbmount]

How often and how much does he feed? Also a sailfin needs at least 100 gal to live comfortably. He needs to cut back on feedings and continue doing water changes, along with cleaning filters and skimmer in the old saltwater.

 

[jimnlee]

Thanks for the reply. I really don't think he's overfeeding. He's very conscientous about that. Can not cleaning the sponge filter in the wet/dry cause a spike like this? I know he did clean it the last time, but I'm not sure about previous times.
Thanks again.

 

[greatfullreefer]

Does he utilize bio-balls in the wet dry? If so this may be the cause, they seem to develop problems after a year if not maintained.

 

[peggy]

If it is only occuring every two months have your friend think about anything (no matter how insignificant it seems) he is doing on a perodic basis to the tank (i.e., adding a chemical, cleaning equipment, etc.). I know he wants to solve the problem right now but if no one has an answer have him keep a daily journel of what he feeds or does with the tank. He should see a pattern developing. Good luck.

 

[jimnlee]

Thanks for your input! Greatful, what specific problems can the bio balls (yes, that's what he has) cause and what can he do to maintain them?
Thanks again.
:help:

 

[rbmount]

Take about a third out and rinse the loose stuff off of them in salt water from a change. If they get particles of uneaten food stuck in them, that will cause high nitrates.

 

[peggy]

Hi Rbmount - People say that dirty bio balls can cause an increase in the nitrate level. Assuming that it can would not the nitrate reading be consistently high and not simply spike every two months? That's why I suspect it's something be added or done to the tank (or even around the tank)