Swim bladder?

[MrsBombastic]

I upgraded from from a 30 to a 45 gal FOWLR tank about 6 months ago. The 30 had been running strong for a little over 2 years and was very healthy. Since upgrading, I seem to only be able to keep more brackish fish alive. Currently 3 sebaes and a very, very boring horseshoe crab. Any introduction of anything remotely exotic dies within a few weeks. Mostly from swim bladder.

The only thing I have changed is that I am now using primed/buffered tap water in place of ro/di water and replaced the old sand with new. I have a protein skimmer and aeration bar.

Current feedings are daily brine shrimp pellets with seaweed and/or frozen block treats 1-2 times per week.

Current levels:
Nitrates: 0 ppm
Nitrites: 0 ppm
Ammonia: 0.25 ppm
Phosphates: 0.25 ppm
pH: 8.0-8.2 ppm
Temp: 77 deg F
Salinity: 28 ppt
Specific gravity: 1.020

What the heck is going on!?

 

[Sniperhank]

I would be concerned about having detectable ammonia levels, but I'll chalk that up to a false positive as it is low.
What I see are high phosphates in the system and your salinity is too low. You don't want your salinity to be lower than 1.024 and no higher than 1.028. I would recommend water changes with ro/di water to adjust your salinity and to correct the phosphate levels in the system. There is a chance that they are simply coming in from the tap water that you are treating to use in the system or that you are simply feeding too much for having no actual livestock in the system.

 

[54seaweed]

I'm confused are we talking brackish or saltwater as there's a difference of what you can keep

 

[MrsBombastic]

Funny that you both point out the same thing. I had an ich outbreak a while back and as a result had lowered the salinity to prevent it from reoccurring. I think in the process I never brought the salinity back up to an acceptable range.
Looking back at my parameters I see that I have a brackish tank. <facepalm>