I agree with Tiger15, that your test kit may be off. Many chemicals have an effective "shelf life", and there is no telling how long they are stored before we buy them. I tend to buy mine from stores that I know sell alot of these items (I feel I get fresh stock more frequently). My suggestion would be to get another test kit and cross-check, possibly using a different brand.
I also agree with JamisonBWolsh, that 150 ppm to 20 ppm in a small water change sounds WIERD to me! Even a 50% change I can't see altering water quality that much. I feel that I understand the nitrogen cycle, and it's effects pretty clearly, and this just doesn't "jive" with what I've learned.
Also, Jamison, you said in a post above that you do weekly 50% waterchanges and still have 80ppm nitrates? Is this right? Could I suggest that you may want to keep an eye on that more closely. I know that tanks stabilize once you have them established, but 80 ppm is getting pretty stressful for long-term exposure. I have done alot of reading on the subject, and anything over 20ppm (or 50ppm by less conservative standards) is stressful, in the long-term for your fish. It's not going to kill them outright, but It MAY BE something like smoking cigarettes is for humans. I understand that you have your own experiences, and I can appreciate that. I am just bringing to light something I thought I'd pass on. The nitrate test kits I use (Red Sea and currently Salifert) both max out at 100ppm on their charts ....that's BAD. Just as a rule, I do about 50% water changes weekly and nitrates go from around 5 ppm (after change) to about 15 ppm (7th day). I have NO PLANTS, just for the record.
From all that you have said, Weasel, I'd suggest:
1) not adding any more fish
2) feed half what you currently do (at least temporarily)
3) do weekly 50% water changes
4) talk to water company (about nitrates in H2O supply)
5) get another Nitrate test kit
Also, your problem will not be affected by adding back tank decorations (fake plants), because all that COULD happen is the bacteria on them will convert ammonia and nitrite to NITRATE.....which is your problem! But removing these things won't help either, mind you
I hope everything clears up for ya!
I also agree with JamisonBWolsh, that 150 ppm to 20 ppm in a small water change sounds WIERD to me! Even a 50% change I can't see altering water quality that much. I feel that I understand the nitrogen cycle, and it's effects pretty clearly, and this just doesn't "jive" with what I've learned.
Also, Jamison, you said in a post above that you do weekly 50% waterchanges and still have 80ppm nitrates? Is this right? Could I suggest that you may want to keep an eye on that more closely. I know that tanks stabilize once you have them established, but 80 ppm is getting pretty stressful for long-term exposure. I have done alot of reading on the subject, and anything over 20ppm (or 50ppm by less conservative standards) is stressful, in the long-term for your fish. It's not going to kill them outright, but It MAY BE something like smoking cigarettes is for humans. I understand that you have your own experiences, and I can appreciate that. I am just bringing to light something I thought I'd pass on. The nitrate test kits I use (Red Sea and currently Salifert) both max out at 100ppm on their charts ....that's BAD. Just as a rule, I do about 50% water changes weekly and nitrates go from around 5 ppm (after change) to about 15 ppm (7th day). I have NO PLANTS, just for the record.
From all that you have said, Weasel, I'd suggest:
1) not adding any more fish
2) feed half what you currently do (at least temporarily)
3) do weekly 50% water changes
4) talk to water company (about nitrates in H2O supply)
5) get another Nitrate test kit
Also, your problem will not be affected by adding back tank decorations (fake plants), because all that COULD happen is the bacteria on them will convert ammonia and nitrite to NITRATE.....which is your problem! But removing these things won't help either, mind you
I hope everything clears up for ya!