GFO and SPS
 

Hey guys, well i recently switched over from biopellets to GFO (had more success with GFO) after rising phosphate levels that reached 0.06ppm. I refilled the TLF reactor with GFO and let'r fly. A few days later i noticed my birdsnet colony (that i almost lost as a frag months ago) had some RTN. I looked at the two frags i made from the same colony and same thing, going white and dying from the inside out? I did several w/c thinking that might help but im wondering if ive stripped the water column so suddenly of phosphate ive 'shocked' these guys? Anyone have any similar experiences? Im sure the cause of why this happened is connected since the colony and two frags all went up at the same time in different areas of the tank.

Yep happened to me when I was using ROWAPHOS. Its because the phosphate is stripped too quickly. ROWAPHOS works really quickly, some other GFO's are slower to remove phosphate which is easier on corals (but some not slow enough especially if your SPS have become used to higher levels of phosphate). Turn down the flow on your phosphate reactor or don't use as much (probably flow would be better/easier) and you should be okay. Its likely that your birdsnest is just the most sensitive of the lot and was affected first. I wouldn't worry about waterchanges, its unlikely that you're going to add phosphate back to the water to level it out.

thanks christy, should i "wait and see" in the next couple days if this RTN will continue to spread on the larger birdsnest colony? or should i frag as much as i can? Id try to cut out of dead zone but its right on the base/in the middle of everything so itd be a pain in the a**.

Yeah birdsnests are a pain that way, I'd just leave the main colony intact, maybe frag a large piece off if you can. Its hard to say how crabby it is about the whole thing and whether the tissue necrosis will continue or whether it will just stay as it is. Its kind of a crap shoot really. If you're totally in love with it, frag a chunk off but if you can get another piece or are indifferent, just wait and see :razz:

Provided your test kit and testing habits are accurate stripping the water of 0.06 ppm of phosphate isn't enough to cause that sort of reaction. Now, if you had 1 ppm and stripped it down to 0.08 ppm or something like that, then maybe you would be havin some issues. I think something else caused your RTN.

Personally I use pellets and GFO. Bacteria utilize NO3 and PO4 in a certain ratio. The bacteria can sometimes become nitrate limited meaning it will consume all the nitrate while there is still phosphate left over.

I was thinking about trying that in the future.

The only other thing i can think i did recently was bring salinity down from 1.028 to 1.026 during a w/c. Unfortunately i did this and added GFO during the same week maybe it was a combination it didnt like.

Going down in salinity by two points won't harm the critters either. Going up is trickier. If the salinity was at 1.028 for awhile that could have been the cause of the RTN. How are you checking salinity?

Vertex Refractometer. I didnt calibrate it for a month and it shifted my reading by 0.002 which is why i did a salinity shift.

I ran my tank at 1.035 for a while without anything bad, so I wouldn't guess salinity.