So I'll just jump in. I agree that you are getting close to completing the cycle but you have some work to do. You now know the proper way so lets move on.
First, I really don't know if a biowheel filter is the best way to maintain a SW
tank. Yes, it can be done but it is usually in addition to live rock. You mentioned going and buying some but is that what you want? If you want a fish only tank then there may be other ways to get you there instead of just getting live rock. IMO
live rock is the way to go, and highly recommend it myself, but you shouldn't be pushed in a direction you don't want to go.
You really need to do a water change ASAP to get those nitrates down. 160 ppm
is really high. I would start doing 3 15-20% water changes every 3-4 days and then once a week to get that down. Are you using RO
water or treated tap? RO
is going to be the best because treated tap will just end up causing algae. The water changes will also help with the nitrite because 10 ppm
is also high and can cause problems for your existing fish.
What are you plans for this tank? Are you planing on getting rid of the damsels once the cycle is done or keeping them? They are pretty aggressive fish and will limit what you can have in the tank.