Chemistry

[rade8em]

I have two tanks

1st tank 2nd tank
Salinity 1.026 Salinity 1.028
PH 8.4 PH 8.6
Ammonia 0 ppm Ammonia 0 ppm
Nitrate 0ppm Nitrate 0 ppm
Phosphate 0.5 Phosphate 0.5
Alk 1.7-2.8 Alk 1.7 - 2.8

Both tanks are invertebrate, (hermit crabs, mushrooms, polyps, Oyster, sand sifting star, feather dusters, curly Q anemone and a large bristle worm)

everytime I try to place a fish in the tank they die within a few weeks. I was having problems with fluctuating salinity I have gotten control of that could it be the PH?

Both tanks are a year old

[longdangler]

Salinity at 1.028 seems a little high IMO but i would think the fish would adjust to it, depending on the type of fish. Could be your PH.

[longdangler]

Calcium high? That would also effect the PH

[SWINGRRRR]

PH and SG are a bit high, but I don't think that would kill fish over a time.

Anything between 7.5 and 8.5 is ok. As close to 8.3 is best, IMHO (not gospel.)
What is your acclimation like? Fish aren't as susceptible to osmoregulation are inverts are, but a big swing can mess them up and lead to mortality.