High Nitrate

Forgot to mention above. Tank is 2 years old with no previous problems since set up. I have several plants and they all look healthy

Hello Steven,

I have had a similar problem in my 7 months old 125L. It has loads of plants, which will be eating some nitrate, but I still found myself doing a w/c every 4-5 days, to keep the nitrate level less than 40ppm. (tap water is 5-10 ppm). Also, the algae, which the oto's had dispensed with, was re-appearing. I eventually came to the conclusion that I was overfeeding, even though my fish were consuming everything immediately. My stocking level is about 85%. I have since reduced my feeding gradually by about 75%, and at last, the water changes are becoming less frequent. The reduction did take a while to show, but it is there.

Also, in the early days, before the tank was cycled, I had very high nitrate levels (160ppm+). I believe that this was due to all the new plants I had added "melting", particularly the cryptocorynes.

Hope this helps,

                                             Skittler

The usual causes of high nitrate, some of which you have already eliminated, are;
high level in tap water
too many fish
too much food
water changes not often enough
water changes not big enough
plant fertiliser

Nitrate testers are the least accurate. But just to check - is yours still in date? The instructions will say to shake one bottle and the test tube very well, are you doing this?


One thing you could try is 50% water changes every day for 3 or 4 days. That should get it down to pretty near the tap level. Then test every day to see how fast it goes back up, if at all.