Nitrate off the chart, but low Ammonia?

[Tropics]

I have a 25 gallon tank which is moderately well planted and gets over 2 wpg of light for 12 hours a day. I had black colored algae on plants and most surfaces. I used to think I had a high phosphate problem so I used Phoban.
The algae seem to have reduced a bit but stilll look quite unsightly.

I have those hang-in-the-water ammonia and ph test dials. Ammonia has
always shown "low" (safe) readings and pH is slightly acidic (6.8). I used
to think I couldn't possibly have a nitrite/nitrate problem since the
source (ammonia) was low, but testing with Mardel test strips shows nitrate "off the scale". (The highest level of nitrate is supposed to show deep purple but mine shows dark grey!)

Two thoughts came to my mind- either the test is measuring nitrate incorrectly or the nitrate is really off the scale. Is this possible with my setup? I do a third (33%) water change every weekend. I use a
50:50 mixture of tap water and RO water since my tap water is quite
hard and alkaline. I use Flourish Excel supplement every other day.

 

[anshuman]

I highly recommend you to go thru my thread posted just some days ago . http://www.myfishtank.net/forum/fre...high-nitrates-goldfish-tank-why-new-post.html


Edit: now about your ammonia/nitrate/ph levels i dont think you are measuring it rightway, Even spent wrongly on strip test, they give low readings than the actual level due to the way they test, its not reliable. Ammonia Nitrite SHOULD BE ZERO. nitrate safe levels are said to be around 40, Check my thread as i said, I did Liquid-test-kit measuring. see the pic, the way it shows colours , its costly but worth it, and it is said you can do 800 test, so should long last and worth the investment.

I strongly recommend you do a 30-40% water change today , tomorrow and one more day, that should remove the excess nitrate if thats the case as mentioned by you.

Thats it from me. i am sure superfish user can reply you more thoroughly. But a real reading by liquid-test-kit is strongly recommended from me. need actual levels of ammonia/nitrate/nitrite and ph. Good luck.

 

[Flowmsp]

I 2nd the vials for test kits, strips could be old or other problems

 

[OrangeCones]

I have those hang-in-the-water ammonia and ph test dials. Ammonia has always shown "low" (safe) readings and pH is slightly acidic (6.8). I used to think I couldn't possibly have a nitrite/nitrate problem since the source (ammonia) was low, but testing with Mardel test strips shows nitrate "off the scale". (The highest level of nitrate is supposed to show deep purple but mine shows dark grey!)

Two thoughts came to my mind- either the test is measuring nitrate incorrectly or the nitrate is really off the scale. Is this possible with my setup? I do a third (33%) water change every weekend. I use a
50:50 mixture of tap water and RO water since my tap water is quite
hard and alkaline. I use Flourish Excel supplement every other day.

I agree with the suggestion of several large water changes to bring the nitrates down, under 20 would be best.

The test dial for ammonia is measuring free ammonia, and should last a year or more. I believe the center disk will change color when its no longer functioning. They work well from what I've heard.

The high nitrates are a end-product of the bacteria cycle, and need to be removed on a regular basis if your plants aren't able to use the ammonia up before the bacteria gets to it (they compete for ammonia).

If it were me, I'd do the large water changes as suggested, measuring the nitrate level the following day. Once you see it get within the normal range (under 20), then test every 2 or 3 days, to get an idea how quickly they build up. You can then adjust the water change schedule.

 

[Tropics]

Thanks all. I bought a API Nitrate test kit and measured after 50% water change.
To reduce the affect of any other variables, I used only RO water. Sure enough, the
nitrate now reads around 20 ppm.

Clearly the strips were giving incorrect readings. It is also possible that the local
San Jose tap water is high in nitrate. Next time, I will measure nitrate levels before
adding it to the aquarium.