I have been slowly trying to get through this thread for the past couple of days, but decided to go ahead and post about my battle. My first dino bloom was back in March and it was mixed. I had both Osteo and large cell Amphidinium. I opted to remove as much of my sand bed as I could and I stopped water changes for 6 weeks. I added a large UV to help with the Osteo. I also dosed Neo-Phos to keep my P04 numbers above .1. The dinos receded and were mostly gone by the end of May. They were replaced by cyano that I has attempting to fight with just siphoning, water changes, and dosing some MB7. In July I decided it was time to put sand back in the tank. I went with reef grade size and only put a .5-1" well rinsed layer.
Well about 2 weeks ago the large cell Amphidinium returned. I am not sure why as I have kept my nitrates at 10 and P04 has been a little high at 60-70ppb on my hanna. This time I am going to try and fight this without removing my sand. I am committed to siphoning every other day into a 5 micron sock. I have upped my MB7 dosing for now and I will still do small water changes every 2 weeks to keep trace elements for other algae to grow.I have tons of sponge growth in my tank so I tend to believe I have Si coming in despite 3 Di stages on my RO. Because of this I am hesitant to dose Si. My tangs keep anything green from growing on my rocks and I have a large population of snails.
This is frustrating because I was just beginning to repopulate my tank with acros. I lost quite a few in the last battle with dinos. I am doing everything I can to increase the biodiversity of my tank. I added 3 pieces of life rock from my LFS that they have had for serveral months in their curing bin. I added a bunch of pods from Algae Barn back in April and I am wondering if I should get more? This time around the dinos are just on the sand and don't seem toxic. Nothing is bothered by them except me. Some photos from last night before the siphoning:
The 5 micron sock after siphoning
Some of the sponge growth in my tank