Doing a 50% to 75% water change at this point is beneficial for the following reasons.
- It replenishes essential sea water trace elements.
- It helps to correct and return changes in pH, alkalinity and other important parameters of the water to their ideal settings.
- It improves the overall quality of the water.
Once the aquarium is cleaned up and refilled, it's time to rinse out or replace any type of mechanical water filtering materials, such as prefilter flosses, cartridges, sponges or pads.
Now let the system run for a few days to allow the filter(s) to polish up the water. If at this point any prefiltering materials appear to be dirty, clean them up again.
- Tip: No water changes should be performed, or any kind of ammonia destroying products added to the water while the tank is cycling, as this only delays and drags out the completion of the cycling process.

