Problem with Leathers

[natureboy]

I have a 75 gal reef tank with mostly soft corals in it. I have had a large toadstool leather for the past 7 or 8 months that has been doing really well. About five weeks ago i put a finger leather in the tank. These are the only two leathers in there. Both were doing well for a few days and then the both started shedding. First the finger leather sheds (which takes about a week) and then looks great for a day or two. The toadstool leather sheds too, but not as frequently as the finger leather. Also, the toadstool has not been in good shape for the last 3-4 weeks. On occasion his polyps extend, but when they do they dont even come all the way out. Most of the time it is small with no polyp extensions and bent over.
My question is could these leathers negatively affect one another or is there a more likely cause in my tank?
salinity 1.024
PH 8.13
KH 10
ammonia 0
nitrites .3
will test for calcium soon but has always been around 340-390 in the past.
salinity, ph

 

[ophiura]

NitRITES or nitRATES are at .3?
IMO, your specific gravity is a touch on the low side but if you have had it for awhile...
But YES, soft corals can have very negative impacts on other corals in the tank, as I have learned the hard way. They may not like each other at all. Do you have the option of moving one to another tank for a short while, to see if it improves? How close together are they?
Otherwise, I would run lots of carbon, and stick to frequent water changes.