How Bad Will My Tank Cycle?

[H2oH2o]

I have a 75 gallon tank, its about 12 months old, i have 2 inches of crushed coral that is just packed with nitrates and waste. I did a test on my nitrate level and its over 160 ppm, which it should be 0!!!!

This weekend i want to take everything out and removes all the crushed coral and put down live sand, I know there will be a massive cycle involved with this?

So my question is, is this safe to do, since i have about 15 pieces of coral and 5 fish, that have already adapted. Also if it is, what steps should i take to go about doing this without causing a massive cycle?

[Jens Kallmeyer]

Don't take all the crushed coral out at once, this is asking for trouble. If you change everything at once, the system may become unstable.
Start by taking a small powerhead and blow as much detritus out of the rocks than possible, there is usually a lot of junk hanging in there. Take a gravel cleaner and suck out as much the detritus from the crushed coral as you can. Do a good 30 % waterchange and let things settle for a week.
Repeat this 3 or 4 times with one week in between to allow things to settle. After this period your nitrates should already be somewhat lower. Replacing the crushed coral should be done in several steps as well, take out a max of 20 to 25% every week and replace it with new substrate.
We had enough cases in our German board where people did the whole change at once, in about 3/4 of all cases this resulted in a complete tank crash. 160 ppm NItrate is really high, but the animals have adjusted to it, give them a chance to adjust to better levels.

Good luck and patience

Jens