Couple things going on...

[kzziboy]

I recently realized that my hydrometer was WAY off and my specific gravity was only at 1.020 - .021. Since then I have purchased a refractometer and I'm currently elevating my salt level. Instead of replacing evaporated water with plain RO/DI water, I'm replacing it with water mixed to 1.026. Slowly it's going up. Right now I'm at 1.024.
Couple concerns though. I have a 55 gallon tank with Live Rock and Xenias. I also have a blue damsel, green chromis and yellow tail blue damsel. I have 2 175 watt MH and 2 T5's. 1 Super Daylight and the other actinic. Plus I have a 20 gallon sump with chaeto.
At the end of September I left town for a few days and came home to a dead Clown fish and a dead Royal Gramma.
NO IDEA WHY! No power failure at all. Months ago I removed my heater with the though of moving it to my sump...still not in there. Wasn't too worried since it has been warm in my house, plus the combination of the lights keeps the water temp from about 78 at night to 82 during the day. Well, when I left I decided to turn OFF my metal halides. Didn't feel like being far away if there was a problem with them. I left my T5's on the timer. So, I'm not sure if the water got too cold for them or what. Either way, the others didn't seem affected at all.
Also, over the last 5 months I have been loosing purple coraline algae. Not a problem for some, but it is for me. It grows like crazy on the glass, but not on my rocks. To top it all off, my rock seems to be getting covered by a thin film of black algae...or maybe its a form of cyno...not sure.
I have a crushed coral substrate. I know there's a lot of detrius in there. I try to vacuum that stuff as best I can, but with Live Rock in there it is tough.
As for my params, my Magnesium is low. I'm guessing that's because my salt level was low. Likewise on my calcium. I haven't tested it in about a week. I need t do that since my salt level is getting close to 1.026.

Any thoughts on my novel here? Hate that black stuff showing up:mad2:. I'll try to get a pic later. I'm at work now.

Thanks!

 

[xray]

Sorry cannot help with the black stuff but make sure you get some pin point solution to calibrate your new meter with. Mine was off on the upper end. It showed 0 using distilled water like they said to do. I then got some pin point calibration fluid which is at .35 or 1026 where you want your water to be and found that my meter was off by .04 so I thought my tank was at 1026 and it was at 1022. Randy has a great write up on hydrometers if you do a search explaining how they can have a variance moving up the scale.

 

[bertoni]

What are the alkalinity and calcium levels? How about nitrate and phosphate?

 

[kzziboy]

Calcium just tested last night...390.
Magnesium also just tested...much better now at 1290.
Nitrates and phosphates show zero.

Did not test Alkalinity.

Oh, and refractometer is calibrated.

 

[kzziboy]

Posting back with Alkalinity...It's at 9 dkh.

 

[coralsnaked]

If you have algae you have nitrates and phospahates no matter what your test results read. And it sounds as if coraline still grows in the tank as evidenced by the glass. Have to assume the algae is covering or killing the coraline on the rock. As far as the fish go, the lower end salinity and trace would not be a problem for them, although the lower Alk could have enabled the pH to swing, but with the loss of heat from the change in lighting it complicates that thought process. I have normally found a fish kill off for unexplained reasons is frequently traced back to a wild pH swing for some reason. How do you handle CO2 in your tank?

 

[kzziboy]

I don't handle CO2 in any way. I have no real means. Suggestions?
Also, my crushed coral bed is about 12 or 13 years old... Is it completely full of the crap I'm trying to get rid of?

 

[bertoni]

If the pH in the tank is okay, the carbon dioxide level is okay. The test results you have are all fine.

The crushed coral might have a lot of detritus trapped in it. Mine did, after a short period, and I threw it away and went with fine sand. That was a big improvement.

 

[kzziboy]

PH has stayed pretty steady. No big swings whenever I've checked it. it always is in the 7.9 to 8.1 range.
Anyone else see big improvements after getting rid of a crushed coral bed? Maybe an older one like mine?

 

[bertoni]

I saw improvements in the nutrient levels in the water and coralline growth.