Massive pwcs and the cycle

[ManannanMacLir]

I have been cycling my tank for at least five weeks. Today I did a 50% water change after one of my zebra danios died. The week before, I had done a 30% water change. Today, before the water change, the nitrites were at 1.00 ppm, and the nitrates at 5.00 ppm. (Ammonia was at zero). I was wondering, how do massive partial water changes affect the cycle? Will it slow the cycle down? By the way, I did not use the gravel vacuum on the whole substrate, just one small spot.

 

[justrelax]

you can do a pwc as often as your parameters require without effecting your cycle. the vast majority of the bacteria colonies you're trying to grow will do so on the filter media, substrate, walls of the tank and decorations. so try to avoid gravel cleaning or scrubbing anything in the tank until the cycle is complete. which is when ammonia and nitrite equal 0, and you see nitrate forming. how many fish are in the tank still?

 

[ManannanMacLir]

Thank you for the advice. To answer your question, there are still five zebra danios in the tank. It is a 55 gallon tank. Don't worry, I only vacuumed a small spot in the substrate.

 

[src]

Keep the Nitrites below 0.5ppm, and don't let the Nitrates creep up too high (20-30 max). You may need to do more frequent water changes for a while.

 

[justrelax]

another thing... five danios really aren't going to produce that much waste. so when your cycle is complete, keep in mind the bio-filter you just grew is probably only capable of handling the waste of those five fish. when you add more fish don't think all will be roses and butterflies... you will need to keep a close eye on those parameters to deal with the mini-cycle you will potentially have. like src said, your goal should be to keep nitrites and ammonia below .05, so pwc's will be a good friend for a while

 

[ManannanMacLir]

After doing the partial water change, I did another test of the water. These are the following results:

Ammonia: 0.00 ppm
Nitrite: between 0.25 and 0.50 ppm
Nitrate: 0.00 ppm

Before the water change these were the readings:

Ammonia: 0.00 ppm
Nitrite: 1.00 ppm
Nitrate: 5.00 ppm

Should I be worried that the Nitrates dropped down to zero after the water change? It seems like I blocked or slowed down the progress of the cycle.

 

[rich311k]

No you just diluted them so much your test cant pick them up. Nothing to worry about.

 

[justrelax]

what kind of test kit are you using, strips or liquid reagent? after a pwc you're parameters should reflect the amount of water you replaced. for example, starting with 40ppm nitrates and doing a 75% pwc would leave you with 10ppm. most likely the test was wrong, or done incorrectly. not trying to be critical here, i screw up tests all the time just make sure you follow the instructions to a T. and it doesn't hurt to do a control test on your tapwater. let it sit out for twenty-four hours then test it, preferably with a liquid test kit as strips are notoriously inaccurate.
oh, and you didn't block or slowdown your cycle, you provided good care for your fish! nice job.

 

[Lonewolfblue]

You are just fine. You might even want to do one more PWC just to get the nitrites down a little more. .5 should be the max. But overall, looks like things are progressing pretty well for you.

 

[Zagz]

Remember when testing after water changes to wait at least 2 hours to get accurate readings. Testing immediately after a water change give very inaccurate reading. Your tank is progressing fine. Not totally cycled but definately getting there.