I have been using the Bio Pellets as well for about a year now. I have a SPS dominated reef tank. The colors are awesome with the bio pellets compared to years of DSB's and Mud Filters. I still use some mud and have a DSB in my connected frag tank. I had a problem with the SPS dieing from the bottom up and found that limiting the buffer to no more than 8dkh stopped the dieing. I keep my tank at just under 8dkh with the calcium around 420 or so. In my experience, I found that the bio-pellets make the tank water much closer to natural seawater as far as nitrates and phosphates are concerned, so the buffer and calcium needs to be in line as well. Natural Sea Water is around 7dkh and 410 calcium balanced. You may consider lowering the buffer down to 7 and see. I bet you will see a stop in the dieing and a clear line where the coral is healing. Also, be carefull with water changes as this will raise the buffer depending on the amount you do. I used to do them once a week at 10-20% and now have cut back to once a month at 15%. Add supps to make up the difference...... Your water changes were most likely changing your alk and thats what led to the dieing in your case. Your addition of any calcium or alk would have added to the problem.
Put a GFO reactor on your tank and run it at a lower amount than you would normaly. You still need phosphate removal, just not as much as before. Check your phosphate levels once a week with a colorimeter and keep it at around .02ppm or lower. Just the pellets alone will not keep them down unless you have no fish and don't feed. Otherwise, put a reactor on it and moderate the flow to keep your tank in line. Speed up the flow if they rise, or slow it down slightly if the test shows 0ppm.
Another thing that you may consider is keeping a balanced ratio in your tank. I never have my calcium unbalanced with the buffer. 450+ calcium breeds a lot of buffer problems with the pellets. Keep things balanced.....7 to 410, or 8 to 430 or so. If your way up there in calcium, then your buffer is just as off. Its not a matter of how much as it is the right amounts. Same with Mg., etc.
Last thing is the most important.....patience. The corals I have had the longest are the easiest to keep. SPS is no exception. Any time you make a change ( like reducing nitrates, reducing phosphates etc., or even increasing them) each coral is affected differently. SPS show the most. Other corals change colors, may not open, etc. Some may not change at all. But your focus should be on stability. Even water changes with a LNS can affect stabilty.
NOTE** If your not running bio-pellets, then discard the above as DSB's and Mud filters, etc. all respond to higher buffer and calcium numbers. 20+ years of it, but never the natural sps colors possible with the LNS that pellets, vodka, or Zeo offer. If you have any questions pm me. I hope this helps as I have no hair left after switching to pellets, but now have a handle on it with an empty wallet.... but its easier than I thought. What you may think you know just might be exactly opposite of what you should be doing with new technology.
thereefranch
210G - Mixed Reef - 50G 'Bio Trac' Sump w/refugium and cheto tumbler - Super Reef Octo 5000 skimmer - 1600w of light - 40G connected frag tank
