So, after MANY water changes the nitrates are around 30 PPM according to the API test. The Salifert reads between the 25 and 50 PPM which confirms the API reading.
I think I will do a couple more changes and I'll be ready to add some fish.
It's been a long battle, but I almost have it under control and my corals have been responding well, except for one colony of Zoos. I see reproduction in my green star polyps and my pulsing Xenia are looking healthier than ever.
Through this I came to the conclusion that the previous owner did not change the water and the nitrates reached more than 300PPM. The livestock got used to those parameters but during the move, when fresh SW was added, the fish couldn't handle the change but the corals and inverts fared just fine. Now, everyone will soon have an ideal environment. I just need to get rid of this hair and bubble algae and a huge bristleworm and I'll be content for a while.