Should I be concerned?

[pmdonnelly]

Started a new tank nearly a month ago. Thought I was near the end of cycling.

Readings 02/05 pH = 7.2, Ammonia NH3/NH4 = .25 ppm, Nitrate NO3 = 5.0 ppm

Readings 02/09 pH = 6.8, Ammonia NH3/NH4 = 0 ppm, Nitrate NO3 = 10.0 ppm

Are these fairly normal readings? Should I be concerned about any of these? I could be slightly off since I am trying to match colors to a card...

Thanks

 

[jsoong]

Looks like your are cycled. <Assuming that you are adding an ammonia source & it remains at zero.> Although to be absolutely sure, you should test that nitrites are zero as well.

The pH drift may be a problem. It is fairly normal to see the pH drop during cycling, and with a large water change, you should be able to get that back to the 7.2 before you add fish.

Water at pH of 7.2 has relatively low buffering capacity. <You can test for the KH, the theoretical KH is ~2 degrees.> You prob can keep it stable when you have fish & are doing weekly pwc's. I would be monitoring that closely for the first few weeks. If it start to drift down, you might consider adding some crushed coral/shells/limestone to increase the buffering capacity & prevent a pH crash.

 

[pmdonnelly]

Just to be clear, at this point I have six fish, 1 platy, 2 mollies, and 3 guppies.

 

[jsoong]

Ah, you are doing a fishy cycle ....

In that case, I would worry about the pH drift. <That is assuming that the reading is accurate ... I can never tell the color too well to be 100% sure.>

I think you should check the pH of your tap & see where you are starting from & compare that to the tank. <Since I can't be too precise with the color card, I usu. run the tests in two separate test-tubes & compare the test tubes side by side.> Also, it would be useful to test the tap water after it had sat out overnight (preferably aerated in a bowl) to see if the tap water has a tendency to drift.

Also, what is the water change history. That might give a clue as to what is going on.

If the pH is indeed drifting downwards, it is an indication of inadequate buffering capacity and you should consider adding a buffer to maintain pH stability. <Crushed coral is prob the most fool-proof way of doing this.>

 

[Mark Hewitt]

What about the nitrites?