Nitrate rant

[betta4me]

Some of you may have seen my post yesterday about my cycle being complete.
I did about a 75% water change, waited a couple hours, tested nitrates and they were at 40 or more...okay, need more water changed. Did another 50%, waited a couple hours went down a smidge....what gives? Waited for my husband to get home so he could carry some buckets Did another 75% which should have pretty much gotten rid of all of them, waited to test this morning and now they're right around 20ish.
The nitrates in my 10Gal are right between 5-10 and my tap water has nearly zero. I don't want to move my GBR from my 10 in to the new tank until the parameters are identical or pretty darn close to it.
Now I'm afraid that waiting too long to add fish is going to start killing off my bacteria. BAH, guess I'm just ranting but would like to know if anyone else has had this experience?

 

[HooKooDooKu]

I recently had a similar situation.

I was fishless cycling a 5 gallon tank at my office. I had tested Nitrate levels with the API liquid test kit, and as best as I could match the color chart (and I have excellent color vision) the best I could tell was that the Nitrate levels were about 40. I did a 50% water change and the next morning the levels were STILL 40. So a few days later, I bring in some API 5-in-1 test strips I had. The test strips gave me a Nitrate level of 140.

So I came to the conclusion that while the liquid tests are accurate for low levels, the strips are better for high levels.

If I'm right (and your experience lends more evidence that I am), when you THOUGHT your levels were about 40, they were more likely around 160. At that level, a 90% PWC is required to bring levels below 20.

As for killing off the bacteria, why are you worried? Just keep feeding the tank a few drops of ammonia each day just like if you were feeding fish. The only difference is that the bacteria are getting the ammonia strait from you rather than from fish food processed by a fish. If your tank is properly cycled, then all the ammonia should be converted to nitrate in about 24 hours, and you just have to keep doing PWC to get the nitrate levels you want.