Todclaret1882 Todclaret1882
  • Just popping in
  • Just popping in
  • Joined: 2017/7/16 8:06
  • From Lancashire
  • Group: Registered Users Basic Membership
  • Posts: 2
  • Posted on: 2017/7/16 8:14
Help with high nitrites but falling nitrates #1
Hello All,

About a month into my fishless cycle all was gong well. However, it's been over two weeks since nitrates appeared and the nitrites are still of the chart. The problem i now have is that nitrates are also falling but no budge in the nitrite.

I have water changed and have been seeding within the FK guidance on fishless cycle however nothing seems to be working. I was being patient but now nitrates are falling I'm concerned as I don't want to have to start all over again.

Any advice?
Fishlady Fishlady
  • Tropical Moderator
  • Tropical Moderator
  • Joined: 2010/7/6 18:26
  • From Worcestershire
  • Group: Moderators Image Admin Caresheets FK Supporter Registered Users Advisers
  • Posts: 12559
  • Posted on: 2017/7/16 9:45
Re: Help with high nitrites but falling nitrates #2
Nitrates shouldn't be falling as there is no mechanism for that to happen. It's more likely that the high nitrite level is interfering with the nitrate test.

Nitrites can climb very high, usually well above the limit of the test so they can be falling again but you can't detect the drop as it takes a while to fall low enough to be within the range of the test kit.

Check your pH and also kH if you have a kH test. It's likely that kH has depleted (it is used by the bacteria) which will have caused a pH drop and will have stalled the cycle. The filter bacteria can't function without carbonates (kH). If this is the case then do a large water change to replenish kH and reduce the nitrite level, then carry on dosing as before.
Todclaret1882 Todclaret1882
  • Just popping in
  • Just popping in
  • Joined: 2017/7/16 8:06
  • From Lancashire
  • Group: Registered Users Basic Membership
  • Posts: 2
  • Posted on: 2017/7/16 10:36
Re: Help with high nitrites but falling nitrates #3
Thanks for the reply. Ph has remain bed at advised levels when I've tested. Erik check again. What would be a good kh level?
Fishlady Fishlady
  • Tropical Moderator
  • Tropical Moderator
  • Joined: 2010/7/6 18:26
  • From Worcestershire
  • Group: Moderators Image Admin Caresheets FK Supporter Registered Users Advisers
  • Posts: 12559
  • Posted on: 2017/7/16 16:02
Re: Help with high nitrites but falling nitrates #4
During cycling kH 3 or more, the higher the better, as the large doses of ammonia need a good amount of kH to be processed. After that it depends on the fish you keep.....soft water fish will need the minimum that allows the filter bacteria to function (2kH or so) ; hard water fish considerably more