Somwthing is Wrong

[VIper]

HI
The Past 2 days my fish have been at the top of the tank gasping for air. Today i noticed my bi-coloured blenny and spoted cardianl dead. I ahve a 28 gallon tank with 25lbs of live rock and 3" DSB.
My levels today are
My herrmit crabs are dieing off.
PH- 8 use to be 8.2 it has dropped
Ammonia-0.25 was 0.5 last time i checked
Nitrate-10 very high was 0 last time
nitrite-1+ was 0.05 last time i checked
Alkalinkity-High
Phosphates-0.5

My levels are crazy. How do i get them back to normal. why has my ph droped
I ahve no idea of what to do can someone please help me out here.

 

[Will C1]

how many fish are in there? did you properly cycle the tank? it sounds like you added fish too soon and go an ammonia spike which in turn is killing everything. do a massive water change 50-75% and run carbon this will help but you might want to start returning stuff tonight to the lfs. most stores will hold it for you for a week or so till you get this under control.

 

[naesco]

Whenever fish are gasping for any cause it is very important that you put an air diffuser in the tank now to add additional oxygen

 

[wombat1]

It says in your sig that you have 1 damsel plus some inverts, and also a blenny and cardinal from your post. How long has this tank been running for?? And how quickly did you add the fish? It sounds like you have all the right basics but you may have added fish too soon, or something may have died unnoticed and is fouling your water. Do you have good circulation in the water? Fish breathing near the surface almost surely means there is a low dissolve oxygen conc. in the water, which can be helped with a powerhead directed at the surface and, as stated, an airstone.

Your tank parameters indicate that there is way too much bioload in the tank. The easiest way to get them back to normal is do some large water changes (make sure you match the new salt water to the temp and salinity of the tank) and don't add anything new for awhile. BTW, your pH dropped because of byproducts of heterotrophic bacteria, but 8.0 is definitely not too low or anything at all to worry about.