oscars and high nitrate

[moneywastedonfish]

hey guys,
My 5 ft 150 gallon is swimming in nitrates ~80 ppm, the other readings are zero and pH is 6.8
Why is my tank so high in nitrates, my tap water has almost zero nitrate, i do plenty of water changes one sometimes two 35% per week. The tank has two oscars and a pleco plus two silver dollars (i know they shoal but these two were in a tank as a pair for ages and i got the two for less then the price of one).
Please help, should i think along the chemical filtration route or just do more water changes. How many water changes would you do on my tank a) to reduce nitrates and B) as a general routine.
Thanks peoples

 

[pnyklr3]

I have battled high nitrates before (much, much higher than 80). Are you overfeeding? THis is usually the number one cause of high nitrates. The only way to get rid of the nitrates is by doing water changes. For now, try doing water changes every other day. Also limit your feeding to about every other day. This should help to bring it down. Watch your fish to make sure they are eating everything. You can leave algae tabs (or whatever you are feeding the plecs) at night when you turn off the lights.

As for the chemical filtration: are you talking about adding in some carbon? I don't think carbon will pull out any nitrates. If you are talking about chemicals themselves, I would just stick to the water changes. No use mucking up the water.

 

[freddyk]

Overfeeding is usually my first guess as well, especially with Oscars. Make sure they're eating everything, but also make sure they don't eat too much. Oscars are pigs, they'll eat and beg and eat and beg until it just starts to mess the tank and decline the fishes health. Because of how much they are capable of eating, and how much they beg, Oscars have got to be one of the most overfed fish around - most people overfeed them, so make sure you aren't one of them.