Quick question about 90% water change after cycling...

[Water Wiggler]

I've been following this cycling process: http://www.aquariumadvice.com/forum...guide-and-faq-to-fishless-cycling-148283.html

Do I have to do the 90% water change the night before I get fish? I'm asking this for two reasons. One reason is that the person who helps me carry the pails of water isn't here. The 2nd reason is that the fish store told me that my fish would be available either tomorrow OR the following day. If it's possible to skip doing it the night before, how much time should I give it before I add my fish?

Thanks in advance for the advice!

 

[dalto]

You are doing the change to remove all the nitrates that build up during the cycle. I would do more than 90% if possible.

How before you add fish really depends on your water. If your water is pretty stable out of the tap than you can do it right before. If the pH shifts over time like many people see than you would probably want to do it 12 or so hours ahead of time.

 

[Water Wiggler]

Thanks for responding! I will definitely do more than 90% if need be. I learned that is necessary the first time I did the big water change.

I tested my PH just now. The API PH reading straight from the tap is a definite 7.6 and the tank water with all the nitrates in it appears to be a 7.4. I have three small pieces of cholla wood, which might be lowering the PH a bit or it lowered over time. I don't know.

 

[Masha]

Water Wiggler, remember when testing your tap ph, to let it stand for 24 hours before doing that test. There are all kinds of gasses (possibly chlorine, carbon dioxide etc) that may outgas during that time and this will change the ph. Typically the ph will drop a bit after 24 hours as these gasses leave the water.

 

[dalto]

7.6 to 7.4 is a pretty small variance.

 

[PB_Smith]

yeah, 12-24 hours before adding fish just to allow everything to reach equilibrium and 7.4-7.6 ph is nice sweet spot for the vast majority of freshwater fish, except African cichlids of course.

 

[Water Wiggler]

Yep. I know that. The lower reading is probably because the tank water has been allowed to sit. It looks like my fish can't be ordered for another two weeks, so I get to have an empty tank of high nitrates until then. It'll give my frogbit and java moss a chance to fill in, I guess. I will definitely do the big water change the night before. Thanks!

 

[Water Wiggler]

Will do! I'm so glad that my PH has finally decided to behave itself. I guess that means I'm truly cycled. Yay! It's also nice to know that my PH is sweet. Ha, ha! Alas, I have to wait another two weeks for my celestial pearl danios. My LFS was unable to find any this week. I will be staring at an empty tank very full of nitrates for a bit longer. I'm trying to be optimistic and thinking that my frogbit and java moss will fill in a bit more, I hope. Thank so much for the advice!