What happens when the lights go out??

So In the past week and a half two fish have died and anomone. All on different days, but all in the same corner of the tank. All have died during the night. Im a little confussed. I dont know whats going on. My levels are still good, and have been this entire week. Both fish were chromis, my clowns have been fine... So what happens when my lights go out and what is going on with my fish!!

 

How old is your tank and how fresh is your live rock? I dont think a mantis would do in an anemone. One thing to remember with water flow the place of death might not actually be the place the death occurred too.

 

I'm thinking it's your oxygen levels. At night, O2 levels drop because photosynthesis stops. To counter this, make sure you have plenty if surface agitation from a power head. Also, do you run a skimmer? Skimmers really help with keeping O2 up.

 

i agree with above, i think i remember you also saying about low ph? am i remembering correctly? this also drops at night. the power head should help.

 

Is the tank open toped? Seems unlikely to have low O2 in an open topped 36g, there is a lot of surface area. If you have glass tops, covering it, that could be another story. Is there a protein skimmer? If so, I would say definitely not low O2 either way though. Also, the low pH at night suggests that it is not low O2, assuming your alkalinity is in a reasonable range. If CO2 is getting into your tank, so it O2.

How many chromis do you have?

 

Tank is almost 2 months old, I think I killed the anemone from mishandling it but it closed up tight in the same corner.

How do I know if I have to much flow? I have a 55gal Aqueon hang on filter that blows water around a ton, and then I added a 900 maxi jet last week. When i put food in the tank, it whips around pretty fast. I could add another power head, but is there a way to tell when enough is enough? And no i do not have a skimmer, I was told with a tank as small as mine that I would not need one as long as I kept up on water changes

My p.h is 7.8 and I checked it with the lights off this morning just out of curisoity.

No the tank is closed, glass lid, I have a couple cats that would love to take a swim! Like i said i do not have a skimmer, i was told I did not need one. My alk levels are good. I had two chromis, one died and i know that they school together so I bought another one, and the new one died. So now I have two clowns and 1 chromis. Is the single chromis okay by himself? I hate to add more fish until I figure out whats going on.

 

Well, chromis are know to kill each other off. So, that's a possibility if you have a bully. Is there a sump? O2 is rarely an issue, but could be if there is no gas exchange.

 

No sump, Im very new to this whole experience and I had no idea what a sump was or even where to start. Someday in the future I will have one though

 

I would test O2 then. Amazon.com: Salifert Oxygen Test Kit: Kitchen & Dining

 

If it is O2, how do I correct it?