[Shades9323]

Tank is cycled and ready to go. 18 fish arriving tomorrow morning. Should I do a big water change tonight or tomorrow morning? Or a small one? I don't even know!

 

[Gibbs]

If you can test your water parameters to see exactly were they are that would be a big indicator of whether you should or shouldn't.
Another question to ask yourself is when the last water change was performed.

Personaly if my parameters were good and i hadn't done a water change for a few days i would do 25%.

Good luck

 

[dielikemoviestars]

Tank size? Water parameters? Fish being added (size, species, number of each)?

 

[Shades9323]

Tank size? Water parameters? Fish being added (size, species, number of each)?

30 gallon long(3 foot). am=0,nitrite=0,nitrate=20ppm. 15 demasoni, 3 yellow lab, 1-2"

Did a water change this morning and got the new fish in. A-ok so far. :thumb:

 

[bmills]

Sounds like your water is good but I'm still with my fellow Aussie Gibbs in suggesting that you do say 10-20% change every couple of days for the first week. This will assist your tank in ramping up to the new bioload. 18 fish is a whole lotta new stuff going into that little ecosystem!