Water changes

[bwitchn]

My tank is currently cycling. It has been a week since start up and my Nitrites are 5.0. Ammonia is at 0. Salinity at 1.024. Silicates 1.0, Phosphate 0.5. It is a biocube 29gal HQI. When do I do the first water change? Do I wait until the cycling completes? Should I do a water now mid-cycle? What about the carbon/filter that sits in the refuge, do I rinse it out? Tank currently is going thru a diatom bloom. I used a shrimp to cycle the tank and it was decomposing and I went to remove it yesterday and it disintegrated in pieces that floated everywhere. Any recommendations?

[dunc101]

Is your nitrites at 0?
Whenever your ammonia and nitrites are 0 and you detect nitrates, your cycle is complete. If you used mainly live rock, I have heard of a complete cycle happening in a week. If you used 100% dry rock, it should take around 4-8 weeks for a complete cycle (took 6 weeks for me with 100% dry rock).

In any case, I would wait 1 week after detecting 0 ammonia, 0 nitrites and some nitrates and verify daily that you don't see any ammonia spike over the course of the week. After that you want to do a very large water change to get your nitrates down under 20 ppm and then add a minimal clean up crew (I wouldn't worry about doing a water change before this during the cycle).

Hope this helps.

[haftafish]

If you used live rock that has stuff growing on it already like i did, then i would do water changes as your tank cycles so that the ammonia doesn't kill everything on the rocks.

[MHG]

well it can take quite a long time for any nitrates to show up at all if you have enough rock.


If the ammonia starts to spike from that shrimp then I would do a WC. If not the bacteria will continue to grow and consume most of it. A simple water change cant really hurt. There would be enough of the shrimp left to keep the cycle going.

[bwitchn]

Thanks. I used all Live Rock and Live Sand. I think I had an undetected ammonia cycle, because my ammonia has registered at 0 with the dead shrimp in the tank that is now disintegrated. My Nitrites are high 5.0. Nitrates are 0 right now. So, when the Nitrites are at 0 and there are some Nitrates, i should do a water change before I add the cleaning crew?